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      Aerosol Generating Procedures and Risk of Transmission of Acute Respiratory Infections to Healthcare Workers: A Systematic Review

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          Abstract

          Aerosol generating procedures (AGPs) may expose health care workers (HCWs) to pathogens causing acute respiratory infections (ARIs), but the risk of transmission of ARIs from AGPs is not fully known. We sought to determine the clinical evidence for the risk of transmission of ARIs to HCWs caring for patients undergoing AGPs compared with the risk of transmission to HCWs caring for patients not undergoing AGPs. We searched PubMed, EMBASE, MEDLINE, CINAHL, the Cochrane Library, University of York CRD databases, EuroScan, LILACS, Indian Medlars, Index Medicus for SE Asia, international health technology agencies and the Internet in all languages for articles from 01/01/1990 to 22/10/2010. Independent reviewers screened abstracts using pre-defined criteria, obtained full-text articles, selected relevant studies, and abstracted data. Disagreements were resolved by consensus. The outcome of interest was risk of ARI transmission. The quality of evidence was rated using the GRADE system. We identified 5 case-control and 5 retrospective cohort studies which evaluated transmission of SARS to HCWs. Procedures reported to present an increased risk of transmission included [n; pooled OR(95%CI)] tracheal intubation [n = 4 cohort; 6.6 (2.3, 18.9), and n = 4 case-control; 6.6 (4.1, 10.6)], non-invasive ventilation [n = 2 cohort; OR 3.1(1.4, 6.8)], tracheotomy [n = 1 case-control; 4.2 (1.5, 11.5)] and manual ventilation before intubation [n = 1 cohort; OR 2.8 (1.3, 6.4)]. Other intubation associated procedures, endotracheal aspiration, suction of body fluids, bronchoscopy, nebulizer treatment, administration of O2, high flow O2, manipulation of O2 mask or BiPAP mask, defibrillation, chest compressions, insertion of nasogastric tube, and collection of sputum were not significant. Our findings suggest that some procedures potentially capable of generating aerosols have been associated with increased risk of SARS transmission to HCWs or were a risk factor for transmission, with the most consistent association across multiple studies identified with tracheal intubation.

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          2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Health Care Settings

          Health Care Infection Control Practices Advisory Committee (HICPAC) Chair Patrick J. Brennan, MD, Professor of Medicine, Division of Infectious Diseases, University of Pennsylvania Medical School Executive Secretary Michael Bell, MD, Division of Health Care Quality Promotion, National Center for Infectious Diseases, Centers for Disease Control and Prevention Members Vicki L. Brinsko, RN, BA, Infection Control Coordinator, Vanderbilt University Medical Center E. Patchen Dellinger, MD, Professor of Surgery, University of Washington School of Medicine Jeffrey Engel, MD, Head, General Communicable Disease Control Branch, North Carolina State Epidemiologist Steven M. Gordon, MD, Chairman, Department of Infections Diseases, Hospital Epidemiologist, Cleveland Clinic Foundation Lizzie J. Harrell, PhD, D(ABMM), Research Professor of Molecular Genetics, Microbiology and Pathology, Associate Director, Clinical Microbiology, Duke University Medical Center Carol O'Boyle, PhD, RN, Assistant Professor, School of Nursing, University of Minnesota David Alexander Pegues, MD, Division of Infectious Diseases, David Geffen School of Medicine at UCLA Dennis M. Perrotta, PhD, CIC, Adjunct Associate Professor of Epidemiology, University of Texas School of Public Health, Texas A&M University School of Rural Public Health Harriett M. Pitt, MS, CIC, RN, Director, Epidemiology, Long Beach Memorial Medical Center Keith M. Ramsey, MD, Professor of Medicine, Medical Director of Infection Control, Brody School of Medicine, East Carolina University Nalini Singh, MD, MPH, Professor of Pediatrics, Epidemiology and International Health, George Washington University Children's National Medical Center Kurt Brown Stevenson, MD, MPH Division of Infectious Diseases, Department of Internal Medicine, Ohio State University Medical Center Philip W. Smith, MD, Chief, Section of Infectious Diseases, Department of Internal Medicine, University of Nebraska Medical Center HICPAC membership (past) Robert A. Weinstein, MD (Chair), Cook County Hospital, Chicago, IL Jane D. Siegel, MD (Co-Chair), University of Texas Southwestern Medical Center, Dallas, TX Michele L. Pearson, MD (Executive Secretary), Centers for Disease Control and Prevention, Atlanta, GA Raymond Y.W. Chinn, MD, Sharp Memorial Hospital, San Diego, CA Alfred DeMaria, Jr, MD, Massachusetts Department of Public Health, Jamaica Plain, MA James T. Lee, MD, PhD, University of Minnesota, Minneapolis, MN William A. Rutala, PhD, MPH, University of North Carolina Health Care System, Chapel Hill, NC William E. Scheckler, MD, University of Wisconsin, Madison, WI Beth H. Stover, RN, Kosair Children's Hospital, Louisville, KY Marjorie A. Underwood, RN, BSN CIC, Mt Diablo Medical Center, Concord, CA HICPAC Liaisons William B. Baine, MD, Liaison to the Agency for Health Care Quality Research Joan Blanchard, RN, MSN, CNOR, Liaison to the Association of Perioperative Registered Nurses Patrick J. Brennan, MD, Liaison to the Board of Scientific Counselors Nancy Bjerke, RN, MPH, CIC, Liaison to the Association of Professionals in Infection Prevention and Control Jeffrey P. Engel, MD, Liaison to the Advisory Committee on Elimination of Tuberculosis David Henderson, MD, Liaison to the National Institutes of Health Lorine J. Jay, MPH, RN, CPHQ, Liaison to the Health Care Resources Services Administration Stephen F. Jencks, MD, MPH, Liaison to the Center for Medicare and Medicaid Services Sheila A. Murphey, MD, Liaison to the Food and Drug Administration Mark Russi, MD, MPH, Liaison to the American College of Occupational and Environmental Medicine Rachel L. Stricof, MPH, Liaison to the Advisory Committee on Elimination of Tuberculosis Michael L. Tapper, MD, Liaison to the Society for Health Care Epidemiology of America Robert A. Wise, MD, Liaison to the Joint Commission on the Accreditation of Health Care Organizations Authors' Associations Jane D. Siegel, MD, Professor of Pediatrics, Department of Pediatrics, University of Texas Southwestern Medical Center Emily Rhinehart, RN, MPH, CIC, CPHQ, Vice President, AIG Consultants, Inc Marguerite Jackson, RN, PhD, CIC, Director, Administrative Unit, National Tuberculosis Curriculum Consortium, Department of Medicine, University of California San Diego Linda Chiarello, RN, MS, Division of Health Care Quality Promotion, National Center for Infectious Diseases, Centers for Disease Control and Prevention Table of contents Executive Summary Abbreviations Part I: Review of the Scientific Data Regarding Transmission of Infectious Agents in Health Care Settings I.A. Evolution of the 2007 Document I.B. Rationale for Standard and Transmission-Based Precautions in Health Care Settings I.B.1. Source of Infectious Agents I.B.2. Susceptible Hosts I.B.3. Modes of Transmission I.B.3.a. Contact Transmission I.B.3.a.i. Direct Contact Transmission I.B.3.a.ii. Indirect Contact Transmission I.B.3.b. Droplet Transmission I.B.3.c. Airborne Transmission I.B.3.d. Emerging Issues and Controversies Concerning Bioaerosols and Airborne Transmission of Infectious Agents I.B.3.d.i. Transmission From Patients I.B.3.d.ii. Transmission From the Environment I.B.3.e. Other Sources of Infection I.C. Infectious Agents of Special Infection Control Interest for Health Care Settings I.C.1. Epidemiologically Important Organisms I.C.1.a. Clostridium difficile I.C.1.b. Multidrug-Resistant Organisms I.C.2. Agents of Bioterrorism I.C.3. Prions I.C.4. Severe Acute Respiratory Syndrome (SARS) I.C.5. Monkeypox I.C.6. Noroviruses I.C.7. Hemorrhagic Fever Viruses I.D. Transmission Risks Associated With Specific Types of Health Care Settings I.D.1. Hospitals I.D.1.a. Intensive Care Units I.D.1.b. Burn Units I.D.1.c. Pediatrics I.D.2. Nonacute Care Settings I.D.2.a. Long-Term Care I.D.2.b. Ambulatory Care I.D.2.c. Home Care I.D.2.d. Other Sites of Health Care Delivery I.E. Transmission Risks Associated With Special Patient Populations I.E.1. Immunocompromised Patients I.E.2. Cystic Fibrosis Patients I.F. New Therapies With Potential Transmissible Infectious Agents I.F.1. Gene Therapy I.F.2. Infections Transmitted Through Blood, Organs and Tissues I.F.3. Xenotransplantation and Tissue Allografts Part II. Fundamental Elements to Prevent Transmission of Infectious Agents in Health Care Settings II.A. Health Care System Components That Influence the Effectiveness of Precautions to Prevent Transmission II.A.1. Administrative Measures II.A.1.a. Scope of Work and Staffing Needs for Infection Control Professionals II.A.1.a.i. Infection Control Liaison Nurse II.A.1.b. Bedside Nurse Staffing II.A.1.c. Clinical Microbiology Laboratory Support II.A.2. Institutional Safety Culture and Organizational Characteristics II.A.3. Adherence of Health Care Workers to Recommended Guidelines II.B. Surveillance for Health Care–Associated Infections II.C. Education of Health Care Workers, Patients, and Families II.D. Hand Hygiene II.E. Personal Protective Equipment for Health Care Workers II.E.1. Gloves II.E.2. Isolation Gowns II.E.3. Face Protection: Masks, Goggles, Face Shields II.E.3.a. Masks II.E.3.b. Goggles and Face Shields II.E.4. Respiratory Protection II.F. Safe Work Practices to Prevent Health Care Worker Exposure to Bloodborne Pathogens II.F.1. Prevention of Needlesticks and Other Sharps-Related Injuries II.F.2. Prevention of Mucous Membrane Contact II.F.2.a. Precautions During Aerosol-Generating Procedures II.G. Patient Placement II.G.1. Hospitals and Long-Term Care Settings II.G.2. Ambulatory Care Settings II.G.3. Home Care II.H. Transport of Patients II.I. Environmental Measures II.J. Patient Care Equipment, Instruments/Devices II.K. Textiles and Laundry II.L. Solid Waste II.M. Dishware and Eating Utensils II.N. Adjunctive Measures II.N.1. Chemoprophylaxis II.N.2. Immunoprophylaxis II.N.3. Management of Visitors II.N.3.a. Visitors as Sources of Infection II.N.3.b. Use of Barrier Precautions by Visitors Part III. HICPAC Precautions to Prevent Transmission of Infectious Agents III.A. Standard Precautions III.A.1. New Standard Precautions for Patients III.A.1.a. Respiratory Hygiene/Cough Etiquette III.A.1.b. Safe Injection Practices III.A.1.c. Infection Control Practices for Special Lumbar Puncture Procedures III.B. Transmission-Based Precautions III.B.1. Contact Precautions III.B.2. Droplet Precautions III.B.3. Airborne Infection Isolation Precautions III.C. Syndromic or Empiric Application of Transmission-Based Precautions III.D. Discontinuation of Precautions III.E. Application of Transmission-Based Precautions in Ambulatory and Home Care Settings III.F. Protective Environment Part IV: Recommendations Appendix A: Type and Duration of Precautions Needed for Selected Infections and Conditions Glossary References Table 1. Recent history of guidelines for prevention of health care–associated infections Table 2. Clinical syndromes or conditions warranting additional empiric transmission-based precautions pending confirmation of diagnosis Table 3. Infection control considerations for high-priority (CDC category A) diseases that may result from bioterrorist attacks or are considered bioterrorist threats Table 4. Recommendations for application of Standard Precautions for the care of all patients in all health care settings Table 5. Components of a protective environment Fig 1. Sequence for donning and removing personal protective equipment Executive Summary The Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Health Care Settings 2007 updates and expands the 1996 Guideline for Isolation Precautions in Hospitals. The following developments led to these revisions of the 1996 guideline: 1. The transition of health care delivery from primarily acute care hospitals to other health care settings (eg, home care, ambulatory care, free-standing specialty care sites, long-term care) created a need for recommendations that can be applied in all health care settings using common principles of infection control practice, yet can be modified to reflect setting-specific needs. Accordingly, the revised guideline addresses the spectrum of health care delivery settings. Furthermore, the term “nosocomial infections“ is replaced by “health care–associated infections” (HAIs), to reflect the changing patterns in health care delivery and difficulty in determining the geographic site of exposure to an infectious agent and/or acquisition of infection. 2. The emergence of new pathogens (eg, severe acute respiratory syndrome coronavirus [SARS-CoV] associated with SARS avian influenza in humans), renewed concern for evolving known pathogens (eg, Clostridium difficile, noroviruses, community-associated methicillin-resistant Staphylococcus aureus [CA-MRSA]), development of new therapies (eg, gene therapy), and increasing concern for the threat of bioweapons attacks, necessitates addressing a broader scope of issues than in previous isolation guidelines. 3. The successful experience with Standard Precautions, first recommended in the 1996 guideline, has led to a reaffirmation of this approach as the foundation for preventing transmission of infectious agents in all health care settings. New additions to the recommendations for Standard Precautions are respiratory hygiene/cough etiquette and safe injection practices, including the use of a mask when performing certain high-risk, prolonged procedures involving spinal canal punctures (eg, myelography, epidural anesthesia). The need for a recommendation for respiratory hygiene/cough etiquette grew out of observations during the SARS outbreaks, when failure to implement simple source control measures with patients, visitors, and health care workers (HCWs) with respiratory symptoms may have contributed to SARS-CoV transmission. The recommended practices have a strong evidence base. The continued occurrence of outbreaks of hepatitis B and hepatitis C viruses in ambulatory settings indicated a need to reiterate safe injection practice recommendations as part of Standard Precautions. The addition of a mask for certain spinal injections grew from recent evidence of an associated risk for developing meningitis caused by respiratory flora. 4. The accumulated evidence that environmental controls decrease the risk of life-threatening fungal infections in the most severely immunocompromised patients (ie, those undergoing allogeneic hematopoietic stem cell transplantation [HSCT]) led to the update on the components of the protective environment (PE). 5. Evidence that organizational characteristics (eg, nurse staffing levels and composition, establishment of a safety culture) influence HCWs' adherence to recommended infection control practices, and thus are important factors in preventing transmission of infectious agents, led to a new emphasis and recommendations for administrative involvement in the development and support of infection control programs. 6. Continued increase in the incidence of HAIs caused by multidrug-resistant organisms (MDROs) in all health care settings and the expanded body of knowledge concerning prevention of transmission of MDROs created a need for more specific recommendations for surveillance and control of these pathogens that would be practical and effective in various types of health care settings. This document is intended for use by infection control staff, health care epidemiologists, health care administrators, nurses, other health care providers, and persons responsible for developing, implementing, and evaluating infection control programs for health care settings across the continuum of care. The reader is referred to other guidelines and websites for more detailed information and for recommendations concerning specialized infection control problems. Parts I, II, and III: Review of the Scientific Data Regarding Transmission of Infectious Agents in Health Care Settings Part I reviews the relevant scientific literature that supports the recommended prevention and control practices. As in the 1996 guideline, the modes and factors that influence transmission risks are described in detail. New to the section on transmission are discussions of bioaerosols and of how droplet and airborne transmission may contribute to infection transmission. This became a concern during the SARS outbreaks of 2003, when transmission associated with aerosol-generating procedures was observed. Also new is a definition of “epidemiologically important organisms” that was developed to assist in the identification of clusters of infections that require investigation (ie multidrug-resistant organisms, C difficile). Several other pathogens of special infection control interest (ie, norovirus, SARS, Centers for Disease Control and Prevention [CDC] category A bioterrorist agents, prions, monkeypox, and the hemorrhagic fever viruses) also are discussed, to present new information and infection control lessons learned from experience with these agents. This section of the guideline also presents information on infection risks associated with specific health care settings and patient populations. Part II updates information on the basic principles of hand hygiene, barrier precautions, safe work practices, and isolation practices that were included in previous guidelines. However, new to this guideline is important information on health care system components that influence transmission risks, including those components under the influence of health care administrators. An important administrative priority that is described is the need for appropriate infection control staffing to meet the ever-expanding role of infection control professionals in the complex modern health care system. Evidence presented also demonstrates another administrative concern: the importance of nurse staffing levels, including ensuring numbers of appropriately trained nurses in intensive care units (ICUs) for preventing HAIs. The role of the clinical microbiology laboratory in supporting infection control is described, to emphasize the need for this service in health care facilities. Other factors that influence transmission risks are discussed, including the adherence of HCWs to recommended infection control practices, organizational safety culture or climate, and education and training. Discussed for the first time in an isolation guideline is surveillance of health care–associated infections. The information presented will be useful to new infection control professionals as well as persons involved in designing or responding to state programs for public reporting of HAI rates. Part III describes each of the categories of precautions developed by the Health Care Infection Control Practices Advisory Committee (HICPAC) and the CDC and provides guidance for their application in various health care settings. The categories of Transmission-Based Precautions are unchanged from those in the 1996 guideline: Contact, Droplet, and Airborne. One important change is the recommendation to don the indicated personal protective equipment (PPE—gowns, gloves, mask) on entry into the patient's room for patients who are on Contact and/or Droplet Precautions, because the nature of the interaction with the patient cannot be predicted with certainty, and contaminated environmental surfaces are important sources for transmission of pathogens. In addition, the PE for patients undergoing allogeneic HSCT, described in previous guidelines, has been updated. Tables, Appendices, and Other Information Five tables summarize important information. Table 1 provides a summary of the evolution of this document. Table 2 gives guidance on using empiric isolation precautions according to a clinical syndrome. Table 3 summarizes infection control recommendations for CDC category A agents of bioterrorism. Table 4 lists the components of Standard Precautions and recommendations for their application, and Table 5 lists components of the PE. Table 1 History of guidelines for isolation precautions in hospitals∗ Year (reference) Document issued Comments 1970 1095 Isolation Techniques for Use in Hospitals, 1st ed • Introduced 7 isolation precaution categories with color-coded cards: strict, respiratory, protective, enteric, wound and skin, discharge, and blood. • No user decision making required. • Simplicity a strength; overisolation prescribed for some infections. 1975 1100 Isolation Techniques for Use in Hospitals, 2nd ed • Same conceptual framework as first edition. 19831096, 1097 Guideline for Isolation Precautions in Hospitals • Provided 2 systems for isolation: category-specific and disease-specific. • Protective isolation eliminated; blood precautions expanded to include body fluids. • Categories included strict, contact, respiratory, acid-fast bacteria, enteric, drainage/secretion, blood and body fluids. • Emphasized decision making by users. 1985-88778, 894 Universal Precautions • Developed in response to the HIV/AIDS epidemic. • Dictated application of blood and body fluid precautions to all patients, regardless of infection status. • Did not apply to feces, nasal secretions, sputum, sweat, tears, urine, or vomitus unless contaminated by visible blood. • Added personal protective equipment to protect health care workers from mucous membrane exposures. • Handwashing recommended immediately after glove removal. • Added specific recommendations for handling needles and other sharp devices; concept became integral to the OSHA's 1991 rule on occupational exposure to blood-borne pathogens in health care settings. 1987 1098 Body Substance Isolation • Emphasized avoiding contact with all moist and potentially infectious body substances except sweat even if blood not present. • Shared some features with Universal Precautions. • Weak on infections transmitted by large droplets or by contact with dry surfaces. • Did not emphasize need for special ventilation to contain airborne infections. • Handwashing after glove removal not specified in the absence of visible soiling. 1996 1 Guideline for Isolation Precautions in Hospitals • Prepared by the Healthcare Infection Control Practices Advisory Committee. • Melded major features of Universal Precautions and body substance isolation into Standard Precautions to be used with all patients at all times. • Included 3 transmission-based precaution categories: Airborne, Droplet, and Contact. • Listed clinical syndromes that should dictate use of empiric isolation until an etiologic diagnosis is established. ∗ Derived from Garner and Simmons. 1099 Table 2 Clinical syndromes or conditions warranting empiric transmission-based precautions in addition to Standard Precautions pending confirmation of diagnosis∗ Clinical syndrome or condition† Potential pathogens‡ Empiric precautions (always includes Standard Precautions) Diarrhea  Acute diarrhea with a likely infectious cause in an incontinent or diapered patient Enteric pathogens§ Contact Precautions (pediatrics and adult) Meningitis Neisseria meningitidis Droplet Precautions for first 24 hours of antimicrobial therapy; mask and face protection for intubation Enteroviruses Contact Precautions for infants and children Mycobacterium tuberculosis Airborne Precautions if pulmonary infiltrate present Airborne Precautions plus Contact Precautions if potentially infectious draining body fluid present Rash or exanthems, generalized, etiology unknown  Petechial/ecchymotic with fever (general) Neisseria meningitides Droplet Precautions for the first 24 hours of antimicrobial therapy  Positive history of travel to an area with an ongoing outbreak of VHF in the 10 days before onset of fever Ebola, Lassa, Marburg viruses Droplet Precautions plus Contact Precautions, with face/eye protection, emphasizing safety sharps and Barrier Precautions when blood exposure likely. N95 or higher-level respiratory protection when aerosol-generating procedure performed Vesicular Varicella-zoster, herpes simplex, variola (smallpox), vaccinia viruses Airborne plus Contact Precautions Vaccinia virus Contact Precautions only if herpes simplex, localized zoster in an immunocompetent host, or vaccinia virus likely Maculopapular with cough, coryza, and fever Rubeola (measles) virus Airborne Precautions Respiratory infections  Cough/fever/upper lobe pulmonary infiltrate in an HIV-negative patient or a patient at low risk for HIV infection M. tuberculosis, respiratory viruses, Streptococcus pneumoniae, Staphylococcus aureus (MSSA or MRSA) Airborne Precautions plus Contact Precautions  Cough/fever/pulmonary infiltrate in any lung location in an HIV-infected patient or a patient at high risk for HIV infection M tuberculosis, respiratory viruses, S pneumoniae, S aureus (MSSA or MRSA) Airborne Precautions plus Contact Precautions; eye/face protection if aerosol-generating procedure performed or contact with respiratory secretions anticipated; Droplet Precautions instead of Airborne Precautions if tuberculosis unlikely and airborne infection isolation room and/or respirator unavailable (tuberculosis more likely in HIV-infected than in HIV-negative individuals)  Cough/fever/pulmonary infiltrate in any lung location in a patient with a history of recent travel (10 to 21 days) to countries with active outbreaks of SARS, avian influenza M tuberculosis, severe acute respiratory syndrome virus (SARS-CoV), avian influenza Airborne plus Contact Precautions plus eye protection; Droplet Precautions instead of Airborne Precautions if SARS and tuberculosis unlikely  Respiratory infections, particularly bronchiolitis and pneumonia, in infants and young children Respiratory syncytial virus, parainfluenza virus, adenovirus, influenza virus, human metapneumovirus Contact plus Droplet Precautions; discontinue Droplet Precautions if adenovirus and influenza ruled out Skin or wound infection  Abscess or draining wound that cannot be covered S aureus (MSSA or MRSA), group A streptococcus Contact Precautions, plus Droplet Precautions for the first 24 hours of appropriate antimicrobial therapy if invasive group A streptococcal disease suspected ∗ Infection control professionals should modify or adapt this table according to local conditions. To ensure that appropriate empiric precautions are implemented always, hospitals must have systems in place to evaluate patients routinely according to these criteria as part of their preadmission and admission care. † Patients with the syndromes or conditions listed below may present with atypical signs or symptoms (eg, neonates and adults with pertussis may not have paroxysmal or severe cough). The clinician's index of suspicion should be guided by the prevalence of specific conditions in the community, as well as clinical judgment. ‡ The organisms listed under the column “Potential Pathogens” are not intended to represent the complete, or even most likely, diagnoses, but rather possible etiologic agents that require additional precautions beyond Standard Precautions until they can be ruled out. § These pathogens include enterohemorrhagic Escherichia coli O157:H7, Shigella spp, hepatitis A virus, noroviruses, rotavirus, and Clostridium difficile. Table 3 Infection control considerations for high-priority (CDC category A) diseases that may result from bioterrorist attacks or are considered bioterrorist threats (see http://www.bt.cdc.gov) Disease Anthrax Site(s) of infection; transmission mode Cutaneous (contact with spores); RT (inhalation of spores); GIT (ingestion of spores [rare]) Cutaneous and inhalation disease have occurred in past bioterrorist incidents Comment: Spores can be inhaled into the lower respiratory tract. The infectious dose of Bacillus anthracis in humans by any route is not precisely known. In primates, the LD50 for an aerosol challenge with B anthracis is estimated to be 8,000 to 50,000 spores; the infectious dose may be as low as 1 to 3 spores. Incubation period Cutaneous: 1 to 12 days; RT: Usually 1 to 7 days, but up to 43 days reported; GIT: 15 to 72 hours Clinical features Cutaneous: Painless, reddish papule that develops a central vesicle or bulla in 1 to 2 days; over the next 3 to 7 days, the lesion becomes pustular and then necrotic, with black eschar and extensive surrounding edema RT: Initial flu-like illness for 1 to 3 days with headache, fever, malaise, cough; by day 4, severe dyspnea and shock. Usually fatal (85% to 90%) if untreated; meningitis develops in 50% of RT cases. GIT: In intestinal form, necrotic, ulcerated edematous lesions develop in intestines with fever, nausea, and vomiting and progression to hematemesis and bloody diarrhea; 25% to 60% mortality Diagnosis Cutaneous: Swabs of lesion (under eschar) for IHC, PCR, and culture; punch biopsy for IHC, PCR, and culture; vesicular fluid aspirate for Gram's stain and culture; blood culture if systemic symptoms present; acute and convalescent sera for ELISA serology RT: CXR or CT demonstrating wide mediastinal widening and/or pleural effusion and hilar abnormalities; blood for culture and PCR; pleural effusion for culture, PCR, and IHC; CSF (if meningeal signs present) for IHC, PCR, and culture; acute and convalescent sera for ELISA serology; pleural and/or bronchial biopsy specimens for IHC GIT: Blood and ascites fluid, stool samples, rectal swabs, and swabs of oropharyngeal lesions, if present, for culture, PCR, and IHC Infectivity Cutaneous: Person-to-person transmission from contact with lesion of untreated patient is possible but rare RT and GIT: Person-to-person transmission does not occur Aerosolized powder, environmental exposures: Highly infectious if aerosolized Recommended precautions Cutaneous: Standard Precautions; Contact Precautions if uncontained copious drainage present RT and GIT: Standard Precautions. Aerosolized powder, environmental exposures: Respirator (N95 mask or powered air-purifying respirator), protective clothing; decontamination of persons with powder on them (see http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5135a3.htm) Hand hygiene: Handwashing for 30 to 60 seconds with soap and water or 2% chlorhexidene gluconate after spore contact; alcohol hand rubs are inactive against spores. 981 Postexposure prophylaxis after environmental exposure: A 60-day course of antimicrobials (doxycycline, ciprofloxacin, or levofloxacin) and postexposure vaccine under IND. Disease Botulism Site(s) of infection; transmission mode GIT: Ingestion of toxin-containing food; RT: Inhalation of toxin containing aerosol. Comment: Toxin ingested or potentially delivered by aerosol in bioterrorist incidents. LD50 for type A is 0.001 μg/mL/kg. Incubation period 1 to 5 days. Clinical features Ptosis, generalized weakness, dizziness, dry mouth and throat, blurred vision, diplopia, dysarthria, dysphonia, and dysphagia, followed by symmetrical descending paralysis and respiratory failure. Diagnosis Clinical diagnosis: identification .of toxin in stool, serology, unless toxin-containing material available for toxin neutralization bioassays. Infectivity Not transmitted from person to person; exposure to toxin necessary for disease. Recommended precautions Standard Precautions. Disease Ebola Hemorrhagic Fever Site(s) of infection; transmission mode As a rule, infection develops after exposure of mucous membranes or RT, or through broken skin or percutaneous injury. Incubation period 2 to 19 days, usually 5 to 10 days Clinical features Febrile illnesses with malaise, myalgias, headache, vomiting, and diarrhea that are rapidly complicated by hypotension, shock, and hemorrhagic features. Massive hemorrhage in 3 feet if possible. ∗ During aerosol-generating procedures on patients with suspected or proven infections transmitted by respiratory aerosols (eg, severe acute respiratory syndrome), wear a fit-tested N95 or higher respirator in addition to gloves, gown, and face/eye protection. Table 5 Components of a protective environment I. Patients: allogeneic hematopoeitic stem cell transplantation only  • Maintain in protective environment (PE) room except for required diagnostic or therapeutic procedures that cannot be performed in the room (eg, radiology, surgery)  • Respiratory protection (eg, N95 respirator) for the patient when leaving PE during periods of construction II. Standard and Expanded Precautions  • Hand hygiene observed before and after patient contact  • Gown, gloves, mask not required for health care workers (HCWs) or visitors for routine entry into the room  • Use of gown, gloves, and mask by HCWs and visitors according to Standard Precautions and as indicated for suspected or proven infections for which transmission-based precautions are recommended III. Engineering  • Central or point-of-use high-efficiency particulate air (HEPA) filters (99.97% efficiency) filters capable of removing particles 0.3 μm in diameter in supply (incoming) air  • Well-sealed rooms:   - Proper construction of windows, doors, and intake and exhaust ports   - Ceilings: smooth, free of fissures, open joints, crevices   - Walls sealed above and below the ceiling   - If leakage detected, locate source and make necessary repairs  • Ventilation to maintain ≥12 air changes/hour  • Directed air flow; air supply and exhaust grills located so that clean, filtered air enters from one side of the room, flows across the patient's bed, and exits on opposite side of the room  • Positive room air pressure in relation to the corridor; pressure differential of >2.5 Pa (0.01-inch water gauge)  • Air flow patterns monitored and recorded daily using visual methods (eg, flutter strips, smoke tubes) or a hand-held pressure gauge  • Self-closing door on all room exits  • Back-up ventilation equipment (eg, portable units for fans or filters) maintained for emergency provision of ventilation requirements for PE areas, with immediate steps taken to restore the fixed ventilation system  • For patients who require both a PE and an airborne infection isolation room (AIIR), use an anteroom to ensure proper air balance relationships and provide independent exhaust of contaminated air to the outside, or place a HEPA filter in the exhaust duct. If an anteroom is not available, place patient in an AIIR and use portable ventilation units, industrial-grade HEPA filters to enhance filtration of spores. IV. Surfaces  • Daily wet-dusting of horizontal surfaces using cloths moistened with EPA-registered hospital disinfectant/detergent  • Avoid dusting methods that disperse dust  • No carpeting in patient rooms or hallways  • No upholstered furniture and furnishings V. Other  • No flowers (fresh or dried) or potted plants in PE rooms or areas  • Vacuum cleaner equipped with HEPA filters when vacuum cleaning is necessary Adapted from Centers for Disease Control and Prevention. 11 A glossary of definitions used in this guideline also is provided. New to this edition of the guideline is a figure showing the recommended sequence for donning and removing PPE used for isolation precautions to optimize safety and prevent self-contamination during removal. Appendix A: Type and Duration of Precautions Recommended for Selected Infections and Conditions Appendix A provides an updated alphabetical list of most infectious agents and clinical conditions for which isolation precautions are recommended. A preamble to the appendix provides a rationale for recommending the use of 1 or more Transmission-Based Precautions in addition to Standard Precautions, based on a review of the literature and evidence demonstrating a real or potential risk for person-to-person transmission in health care settings. The type and duration of recommended precautions are presented, with additional comments concerning the use of adjunctive measures or other relevant considerations to prevent transmission of the specific agent. Relevant citations are included. Prepublication of the Guideline on Preventing Transmission of MDROs New to this guideline is a comprehensive review and detailed recommendations for prevention of transmission of MDROs. This portion of the guideline was published electronically in October 2006 and updated in November 2006 (Siegel JD, Rhinehart E, Jackson M, Chiarello L and HICPAC. Management of multidrug-resistant organisms in health care settings, 2006; available from http://www.cdc.gov/ncidod/dhqp/pdf/ar/mdroGuideline2006.pdf), and is considered a part of the Guideline for Isolation Precautions. This section provides a detailed review of the complex topic of MDRO control in health care settings and is intended to provide a context for evaluation of MDRO at individual health care settings. A rationale and institutional requirements for developing an effective MDRO control program are summarized. Although the focus of this guideline is on measures to prevent transmission of MDROs in health care settings, information concerning the judicious use of antimicrobial agents also is presented, because such practices are intricately related to the size of the reservoir of MDROs, which in turn influences transmission (eg, colonization pressure). Two tables summarize recommended prevention and control practices using 7 categories of interventions to control MDROs: administrative measures, education of HCWs, judicious antimicrobial use, surveillance, infection control precautions, environmental measures, and decolonization. Recommendations for each category apply to and are adapted for the various health care settings. With the increasing incidence and prevalence of MDROs, all health care facilities must prioritize effective control of MDRO transmission. Facilities should identify prevalent MDROs at the facility, implement control measures, assess the effectiveness of control programs, and demonstrate decreasing MDRO rates. A set of intensified MDRO prevention interventions is to be added if the incidence of transmission of a target MDRO is not decreasing despite implementation of basic MDRO infection control measures, and when the first case of an epidemiologically important MDRO is identified within a health care facility. Summary This updated guideline responds to changes in health care delivery and addresses new concerns about transmission of infectious agents to patients and HCWs in the United States and infection control. The primary objective of the guideline is to improve the safety of the nation's health care delivery system by reducing the rates of HAIs. Abbreviations Used in the Guideline AIA American Institute of Architects AIIR Airborne infection isolation room CDC Centers for Disease Control and Prevention CF Cystic fibrosis CJD Creutzfeld-Jakob Disease ESBL Extended-spectrum beta-lactamase FDA Food and Drug Administration HAI Health care–associated infection HBV Hepatitis B virus HCV Hepatitis C virus HEPA High-efficiency particulate air HICPAC Health Care Infection Control Practices Advisory Committee HIV Human immunodeficiency virus HCW Health care worker HFV Hemorrhagic fever virus HSCT Hematopoetic stem cell transplantation ICP Infection prevention and control professional ICU Intensive care unit LTCF Long-term care facility MDR-GNB Multidrug-resistant gram-negative bacilli MDRO Multidrug-resistant organism MRSA Methicillin-resistant Staphylococcus aureus MSSA Methicillin-susceptible Staphylococcus aureus NICU Neonatal intensive care unit NIOSH National Institute for Occupational Safety and Health NNIS National Nosocomial Infection Surveillance NSSP Nonsusceptible Streptococcus pneumoniae OSHA Occupational Safety and Health Administration PCR Polymerase chain reaction PE Protective environment PFGE Pulsed-field gel electrophoresis PICU Pediatric intensive care unit PPE Personal protective equipment RSV Respiratory syncytial virus SARS Severe acute respiratory syndrome vCJD variant Creutzfeld-Jakob disease VISA Vancomycin-intermediate/resistannt Staphylococcus aureus VRE Vancomycin-resistant enterococci VRSA Vancomycin-resistant Staphylococcus aureus WHO World Health Organization Part I: Review of Scientific Data Regarding Transmission of Infectious Agents in Health Care Settings I.A. Evolution of the 2007 Document The Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Health care Settings 2007 builds on a series of isolation and infection prevention documents promulgated since 1970. These previous documents are summarized and referenced in Table 1 and in Part I of the 1996 Guideline for Isolation Precautions in Hospitals. 1 I.A.1. Objectives and Methods The objectives of this guideline are to (1) provide infection control recommendations for all components of the health care delivery system, including hospitals, long-term care facilities, ambulatory care, home care, and hospice; (2) reaffirm Standard Precautions as the foundation for preventing transmission during patient care in all health care settings; (3) reaffirm the importance of implementing Transmission-Based Precautions based on the clinical presentation or syndrome and likely pathogens until the infectious etiology has been determined (Table 2); and (4) provide epidemiologically sound and, whenever possible, evidence-based recommendations. This guideline is designed for use by individuals who are charged with administering infection control programs in hospitals and other health care settings. The information also will be useful for other HCWs, health care administrators, and anyone needing information about infection control measures to prevent transmission of infectious agents. Commonly used abbreviations are provided, and terms used in the guideline are defined in the Glossary. Medline and PubMed were used to search for relevant studies published in English, focusing on those published since 1996. Much of the evidence cited for preventing transmission of infectious agents in health care settings is derived from studies that used “quasi-experimental designs,” also referred to as nonrandomized preintervention and postintervention study designs. 2 Although these types of studies can provide valuable information regarding the effectiveness of various interventions, several factors decrease the certainty of attributing improved outcome to a specific intervention. These include: difficulties in controlling for important confounding variables, the use of multiple interventions during an outbreak, and results that are explained by the statistical principle of regression to the mean (eg, improvement over time without any intervention). 3 Observational studies remain relevant and have been used to evaluate infection control interventions.4, 5 The quality of studies, consistency of results, and correlation with results from randomized controlled trials, when available, were considered during the literature review and assignment of evidence-based categories (see Part IV: Recommendations) to the recommendations in this guideline. Several authors have summarized properties to consider when evaluating studies for the purpose of determining whether the results should change practice or in designing new studies.2, 6, 7 I.A.2. Changes or Clarifications in Terminology This guideline contains 4 changes in terminology from the 1996 guideline: 1. The term “nosocomial infection” is retained to refer only to infections acquired in hospitals. The term “health care–associated infection” (HAI) is used to refer to infections associated with health care delivery in any setting (eg, hospitals, long-term care facilities, ambulatory settings, home care). This term reflects the inability to determine with certainty where the pathogen was acquired, because patients may be colonized with or exposed to potential pathogens outside of the health care setting before receiving health care, or may develop infections caused by those pathogens when exposed to the conditions associated with delivery of health care. In addition, patients frequently move among the various settings within the health care system. 8 2. A new addition to the practice recommendations for Standard Precautions is respiratory hygiene/cough etiquette. Whereas Standard Precautions generally apply to the recommended practices of HCWs during patient care, respiratory hygiene/cough etiquette applies broadly to all persons who enter a health care setting, including HCWs, patients, and visitors. These recommendations evolved from observations during the SARS epidemic that failure to implement basic source control measures with patients, visitors, and HCWs with signs and symptoms of respiratory tract infection may have contributed to SARS-CoV transmission. This concept has been incorporated into CDC planning documents for SARS and pandemic influenza.9, 10 3. The term “Airborne Precautions” has been supplemented by the term “Airborne Infection Isolation Room” (AIIR), to achieve consistency with the Guidelines for Environmental Infection Control in Health Care Facilities, 11 the Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health Care Settings 2005, 12 and the American Institute of Architects (AIA) 2006 guidelines for design and construction of hospitals. 13 4. A set of prevention measures known as the protective environment (PE) has been added to the precautions for preventing HAIs. These measures, which have been defined in previous guidelines, consist of engineering and design interventions aimed at decreasing the risk of exposure to environmental fungi for severely immunocompromised patients undergoing allogeneic HSCT during the times of highest risk, usually the first 100 days posttransplantation or longer in the presence of graft-versus-host disease.11, 13, 14, 15 Recommendations for a PE apply only to acute care hospitals that provide care to patients undergoing HSCT. I.A.3. Scope This guideline, like its predecessors, focuses primarily on interactions between patients and health care providers. The Guidelines for the Prevention of MDRO Infection were published separately in November 2006 and are available online at http://www.cdc.gov/ncidod/dhqp/index.html. Several other HICPAC guidelines to prevent transmission of infectious agents associated with health care delivery are cited, including Guideline for Hand Hygiene, Guideline for Environmental Infection Control, Guideline for Prevention of Health Care–Associated Pneumonia, and Guideline for Infection Control in Health Care Personnel.11, 14, 16, 17 In combination, these provide comprehensive guidance on the primary infection control measures for ensuring a safe environment for patients and HCWs. This guideline does not discuss in detail specialized infection control issues in defined populations that are addressed elsewhere (eg, Recommendations for Preventing Transmission of Infections Among Chronic Hemodialysis Patients, Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health Care Facilities 2005, Guidelines for Infection Control in Dental Health Care Settings, and Infection Control Recommendations for Patients With Cystic Fibrosis.12, 18, 19, 20 An exception has been made by including abbreviated guidance for a PE used for allogeneic HSCT recipients, because components of the PE have been defined more completely since publication of the Guidelines for Preventing Opportunistic Infections Among HSCT Recipients in 2000 and the Guideline for Environmental Infection Control in Health Care Facilities.11, 15 I.B. Rationale for Standard and Transmission-Based Precautions in Health Care Settings Transmission of infectious agents within a health care setting requires 3 elements: a source (or reservoir) of infectious agents, a susceptible host with a portal of entry receptive to the agent, and a mode of transmission for the agent. This section describes the interrelationship of these elements in the epidemiology of HAIs. I.B.1. Sources of Infectious Agents Infectious agents transmitted during health care derive primarily from human sources but inanimate environmental sources also are implicated in transmission. Human reservoirs include patients,20, 21, 22, 23, 24, 25, 26, 27, 28 HCWs,17, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 and household members and other visitors.40, 41, 42, 43, 44, 45 Such source individuals may have active infections, may be in the asymptomatic and/or incubation period of an infectious disease, or may be transiently or chronically colonized with pathogenic microorganisms, particularly in the respiratory and gastrointestinal tracts. Other sources of HAIs are the endogenous flora of patients (eg, bacteria residing in the respiratory or gastrointestinal tract).46, 47, 48, 49, 50, 51, 52, 53, 54 I.B.2. Susceptible Hosts Infection is the result of a complex interrelationship between a potential host and an infectious agent. Most of the factors that influence infection and the occurrence and severity of disease are related to the host. However, characteristics of the host–agent interaction as it relates to pathogenicity, virulence, and antigenicity also are important, as are the infectious dose, mechanisms of disease production, and route of exposure. 55 There is a spectrum of possible outcomes after exposure to an infectious agent. Some persons exposed to pathogenic microorganisms never develop symptomatic disease, whereas others become severely ill and even die. Some individuals are prone to becoming transiently or permanently colonized but remain asymptomatic. Still others progress from colonization to symptomatic disease either immediately after exposure or after a period of asymptomatic colonization. The immune state at the time of exposure to an infectious agent, interaction between pathogens, and virulence factors intrinsic to the agent are important predictors of an individual's outcome. Host factors such as extremes of age and underlying disease (eg, diabetes56, 57, human immunodeficiency virus/acquired immune deficiency syndrome [HIV/AIDS],58, 59 malignancy, and transplantation18, 60, 61) can increase susceptibility to infection, as can various medications that alter the normal flora (eg, antimicrobial agents, gastric acid suppressors, corticosteroids, antirejection drugs, antineoplastic agents, immunosuppressive drugs). Surgical procedures and radiation therapy impair defenses of the skin and other involved organ systems. Indwelling devices, such as urinary catheters, endotracheal tubes, central venous and arterial catheters,62, 63, 64 and synthetic implants, facilitate development of HAIs by allowing potential pathogens to bypass local defenses that ordinarily would impede their invasion and by providing surfaces for development of biofilms that may facilitate adherence of microorganisms and protect from antimicrobial activity. 65 Some infections associated with invasive procedures result from transmission within the health care facility; others arise from the patient's endogenous flora.46, 47, 48, 49, 50 High-risk patient populations with noteworthy risk factors for infection are discussed further in Sections I.D, I.E, and I.F. I.B.3. Modes of Transmission Several classes of pathogens can cause infection, including bacteria, viruses, fungi, parasites, and prions. The modes of transmission vary by type of organism, and some infectious agents may be transmitted by more than 1 route. Some are transmitted primarily by direct or indirect contact, (eg, herpes simplex virus [HSV], respiratory syncytial virus, S aureus), others by the droplet, (eg, influenza virus, Bordetella pertussis) or airborne routes (eg, Mycobacterium tuberculosis). Other infectious agents, such as bloodborne viruses (eg, hepatitis B virus [HBV], hepatitis C virus [HCV], HIV), are rarely transmitted in health care settings through percutaneous or mucous membrane exposure. Importantly, not all infectious agents are transmitted from person to person; these are listed in Appendix A. The 3 principal routes of transmission—contact, droplet, and airborne—are summarized below. I.B.3.a Contact Transmission The most common mode of transmission, contact transmission is divided into 2 subgroups: direct contact and indirect contact. I.B.3.a.i Direct Contact Transmission Direct transmission occurs when microorganisms are transferred from an infected person to another person without a contaminated intermediate object or person. Opportunities for direct contact transmission between patients and HCWs have been summarized in HICPAC's Guideline for Infection Control in Health Care Personnel, 1998 17 and include the following: • Blood or other blood-containing body fluids from a patient directly enters a HCW's body through contact with a mucous membrane 66 or breaks (ie, cuts, abrasions) in the skin. 67 • Mites from a scabies-infested patient are transferred to a HCW's skin while he or she is in direct ungloved contact with the patient's skin.68, 69 • A HCW develops herpetic whitlow on a finger after contact with HSV when providing oral care to a patient without using gloves, or HSV is transmitted to a patient from a herpetic whitlow on an ungloved hand of a HCW.70, 71 I.B.3.a.ii Indirect Contact Transmission Indirect transmission involves the transfer of an infectious agent through a contaminated intermediate object or person. In the absence of a point-source outbreak, it is difficult to determine how indirect transmission occurs. However, extensive evidence cited in the Guideline for Hand Hygiene in Health Care Settings suggests that the contaminated hands of HCWs are important contributors to indirect contact transmission. 16 Examples of opportunities for indirect contact transmission include the following: • A HCWs' hands may transmit pathogens after touching an infected or colonized body site on 1 patient or a contaminated inanimate object, if hand hygiene is not performed before touching another patient.72, 73 • Patient-care devices (eg, electronic thermometers, glucose monitoring devices) may transmit pathogens if devices contaminated with blood or body fluids are shared between patients without cleaning and disinfecting between patients.74, 75, 76, 77 • Shared toys may become a vehicle for transmitting respiratory viruses (eg, respiratory syncytial virus [RSV]24, 78, 79 or pathogenic bacteria (eg, Pseudomonas aeruginosa 80 ) among pediatric patients. • Instruments that are inadequately cleaned between patients before disinfection or sterilization (eg, endoscopes or surgical instruments)81, 82, 83, 84, 85 or that have manufacturing defects that interfere with the effectiveness of reprocessing86, 87 may transmit bacterial and viral pathogens. Clothing, uniforms, laboratory coats, or isolation gowns used as PPE may become contaminated with potential pathogens after care of a patient colonized or infected with an infectious agent, (eg, MRSA, 88 vancomycin-resistant enterococci [VRE], 89 and C difficile 90 ). Although contaminated clothing has not been implicated directly in transmission, the potential exists for soiled garments to transfer infectious agents to successive patients. I.B.3.b Droplet Transmission Droplet transmission is technically a form of contact transmission; some infectious agents transmitted by the droplet route also may be transmitted by direct and indirect contact routes. However, in contrast to contact transmission, respiratory droplets carrying infectious pathogens transmit infection when they travel directly from the respiratory tract of the infectious individual to susceptible mucosal surfaces of the recipient, generally over short distances, necessitating facial protection. Respiratory droplets are generated when an infected person coughs, sneezes, or talks91, 92 or during such procedures as suctioning, endotracheal intubation,93, 94, 95, 96 cough induction by chest physiotherapy, 97 and cardiopulmonary resuscitation.98, 99 Evidence for droplet transmission comes from epidemiologic studies of disease outbreaks,100, 101, 102, 103 from experimental studies, 104 and from information on aerosol dynamics.91, 105 Studies have shown that the nasal mucosa, conjunctivae, and, less frequently, the mouth are susceptible portals of entry for respiratory viruses. 106 The maximum distance for droplet transmission is currently unresolved; pathogens transmitted by the droplet route have not been transmitted through the air over long distances, in contrast to the airborne pathogens discussed below. Historically, the area of defined risk has been a distance of 5 μm in size. Droplet nuclei (ie, particles arising from desiccation of suspended droplets) have been associated with airborne transmission and defined as 3 feet but within a defined air space (eg, patient room), suggesting that it is unlikely that these agents remain viable on air currents that travel long distances. AIIRs are not routinely required to prevent transmission of these agents. Additional issues concerning small-particle aerosol transmission of agents that are most frequently transmitted by the droplet route are discussed below. I.B.3.d Emerging Issues Concerning Airborne Transmission of Infectious Agents I.B.3.d.i Transmission From Patients The emergence of SARS in 2002, the importation of monkeypox into the United States in 2003, and the emergence of avian influenza present challenges to the assignment of isolation categories due to conflicting information and uncertainty about possible routes of transmission. Although SARS-CoV is transmitted primarily by contact and/or droplet routes, airborne transmission over a limited distance (eg, within a room) has been suggested, although not proven.134, 135, 136, 137, 138, 139, 140, 141 This is true of other infectious agents as well, such as influenza virus 130 and noroviruses.132, 142, 143 Influenza viruses are transmitted primarily by close contact with respiratory droplets,23, 102 and acquisition by HCWs has been prevented by Droplet Precautions, even when positive-pressure rooms were used in one center. 144 However, inhalational transmission could not be excluded in an outbreak of influenza in the passengers and crew of an aircraft. 130 Observations of a protective effect of ultraviolet light in preventing influenza among patients with tuberculosis during the influenza pandemic of 1957–1958 have been used to suggest airborne transmission.145, 146 In contrast to the strict interpretation of an airborne route for transmission (ie, long distances beyond the patient room environment), short-distance transmission by small-particle aerosols generated under specific circumstances (eg, during endotracheal intubation) to persons in the immediate area near the patient also has been demonstrated. Aerosolized particles 20% of all HAIs. 316 In the National Nosocomial Infection Surveillance (NNIS) system, 26.6% of HAIs were reported from ICU and high-risk nursery (neonatal ICU [NICU]) patients in 2002 (NNIS, unpublished data). This patient population has increased susceptibility to colonization and infection, especially with MDROs and Candida spp,317, 318 because of underlying diseases and conditions, the invasive medical devices and technology used in their care (eg central venous catheters and other intravascular devices, mechanical ventilators, extracorporeal membrane oxygenation, hemodialysis/filtration, pacemakers, implantable left-ventricular assist devices), the frequency of contact with HCWs, prolonged lengths of stay, and prolonged exposure to antimicrobial agents.319, 320, 321, 322, 323, 324, 325, 326, 327, 328, 329, 330 Furthermore, adverse patient outcomes in this setting are more severe and are associated with a higher mortality. 331 Outbreaks associated with various bacterial, fungal, and viral pathogens due to common-source and person-to-person transmissions are frequent in adult ICUs and pediatric ICUs (PICUs).31, 332, 333, 334, 335, 336, 337 I.D.1.b Burn Units Burn wounds can provide optimal conditions for colonization, infection, and transmission of pathogens; infection acquired by burn patients is a frequent cause of morbidity and mortality.319, 338, 339 The risk of invasive burn wound infection is particularly high in patients with a burn injury involving > 30% of the total body surface area (TBSA).340, 341 Infections occurring in patients with burn injuries involving 3 feet), in addition to source control measures, may limit exposures. However, infections transmitted through the airborne route (eg, M tuberculosis, measles, chickenpox) require additional precautions.12, 125, 828 Patients suspected of having such an infection can wear a surgical mask for source containment, if tolerated, and should be placed in an examination room (preferably an AIIR) as soon as possible. If this is not possible, then having the patient wear a mask and segregating the patient from other patients in the waiting area will reduce the risk of exposing others. Because the person(s) accompanying the patient also may be infectious, application of the same infection control precautions may be extended to these persons if they are symptomatic.21, 251, 829 Family members accompanying children admitted with suspected M tuberculosis have been found to have unsuspected pulmonary tuberculosis with cavitary lesions, even when asymptomatic.42, 830 Patients with underlying conditions that increase their susceptibility to infection (eg, immunocompromised status43, 44 or cystic fibrosis 20 ) require special efforts to protect them from exposure to infected patients in common waiting areas. Informing the receptionist of their infection risk on arrival allows appropriate steps to further protect these patients from infection. In some cystic fibrosis clinics, to avoid exposure to other patients who could be colonized with B cepacia, patients have been given beepers on registration so that they may leave the area and receive notification to return when an examination room becomes available. 831 II.G.3. Home Care In home care, patient placement concerns focus on protecting others in the home from exposure to an infectious household member. For individuals who are especially vulnerable to adverse outcomes associated with certain infections, it may be beneficial to either remove them from the home or segregate them within the home. Persons who are not part of the household may need to be prohibited from visiting during the period of infectivity. For example, in a situation where a patient with pulmonary tuberculosis is contagious and being cared for at home, very young children (age under 4 years) 832 and immunocompromised persons who have not yet been infected should be removed or excluded from the household. During the SARS outbreak of 2003, segregation of infected persons during the communicable phase of the illness was found to be beneficial in preventing household transmission.249, 833 II.H. Transport of Patients Several principles guide the transport of patients requiring Transmission-Based Precautions. In the inpatient and residential settings, these include the following: 1. Limiting transport of such patients to essential purposes, such as diagnostic and therapeutic procedures that cannot be performed in the patient's room. 2. When transport is necessary, applying appropriate barriers on the patient (eg, mask, gown, wrapping in sheets or use of impervious dressings to cover the affected areas) when infectious skin lesions or drainage are present, consistent with the route and risk of transmission. 3. Notifying HCWs in the receiving area of the patient's impending arrival and of the necessary precautions to prevent transmission. 4. For patients being transported outside the facility, informing the receiving facility and the medi-van or emergency vehicle personnel in advance about the type of Transmission-Based Precautions being used. For tuberculosis, additional precautions may be needed in a small shared air space, such as in an ambulance. 12 II.I. Environmental Measures Cleaning and disinfecting noncritical surfaces in patient care areas is an aspect of Standard Precautions. In general, these procedures do not need to be changed for patients on Transmission-Based Precautions. The cleaning and disinfection of all patient care areas is important for frequently touched surfaces, especially those closest to the patient, which are most likely to be contaminated (eg, bedrails, bedside tables, commodes, doorknobs, sinks, surfaces and equipment in close proximity to the patient).11, 72, 73, 834 The frequency or intensity of cleaning may need to be changed, based on the patient's level of hygiene and the degree of environmental contamination and for certain infectious agents with reservoirs in the intestinal tract. 54 This may be particularly important in LTCFs and pediatric facilities, where patients with stool and urine incontinence are encountered more frequently. In addition, increased frequency of cleaning may be needed in a PE to minimize dust accumulation. 11 Special recommendations for cleaning and disinfecting environmental surfaces in dialysis centers have been published previously. 18 In all health care settings, administrative, staffing, and scheduling activities should prioritize the proper cleaning and disinfection of surfaces that could be implicated in transmission. During a suspected or proven outbreak in which an environmental reservoir is suspected, routine cleaning procedures should be reviewed, and the need for additional trained cleaning staff should be assessed. Adherence should be monitored and reinforced to promote consistent and correct cleaning. US Environmental Protection Agency–registered disinfectants or detergents/disinfectants that best meet the overall needs of the health care facility for routine cleaning and disinfection should be selected.11, 835 In general, use of the existing facility detergent/disinfectant according to the manufacturer's recommendations for amount, dilution, and contact time is sufficient to remove pathogens from surfaces of rooms where colonized or infected individuals were housed. This includes those pathogens that are resistant to multiple classes of antimicrobial agents (eg, C difficile, VRE, MRSA, MDR-GNB11, 24, 88, 434, 745, 795, 836). Most often, environmental reservoirs of pathogens during outbreaks are related to a failure to follow recommended procedures for cleaning and disinfection, rather than to the specific cleaning and disinfectant agents used.837, 838, 839, 840 Certain pathogens (eg, rotavirus, noroviruses, C difficile) may be resistant to some routinely used hospital disinfectants.274, 291, 841, 842, 843, 844, 845, 846 The role of specific disinfectants in limiting transmission of rotavirus has been demonstrated experimentally. 841 Also, because C difficile may display increased levels of spore production when exposed to non–chlorine-based cleaning agents, and because these spores are more resistant than vegetative cells to commonly used surface disinfectants, some investigators have recommended the use of a 1:10 dilution of 5.25% sodium hypochlorite (household bleach) and water for routine environmental disinfection of rooms of patients with C difficile when there is continued transmission.843, 847 One study found an association between the use of a hypochlorite solution and decreased rates of C difficile infections. 846 The need to change disinfectants based on the presence of these organisms can be determined in consultation with the infection control committee.11, 846, 847 Detailed recommendations for disinfection and sterilization of surfaces and medical equipment that have been in contact with prion-containing tissue or high risk body fluids, and for cleaning of blood and body substance spills, are available in the Guidelines for Environmental Infection Control in Health Care Facilities 11 and in the Guideline for Disinfection and Sterilization. 847 II.J. Patient Care Equipment and Instruments/Devices Medical equipment and instruments/devices must be cleaned and maintained according to the manufacturers' instructions to prevent patient-to-patient transmission of infectious agents.86, 87, 324, 848 Cleaning to remove organic material always must precede high-level disinfection and sterilization of critical and semicritical instruments and devices, because residual proteinacous material reduces the effectiveness of the disinfection and sterilization processes.835, 847 Noncritical equipment, such as commodes, intravenous pumps, and ventilators, must be thoroughly cleaned and disinfected before being used on another patient. All such equipment and devices should be handled in a manner that will prevent HCW and environmental contact with potentially infectious material. It is important to include computers and personal digital assistants used in patient care in policies for cleaning and disinfection of noncritical items. The literature on contamination of computers with pathogens has been summarized, 849 and 2 reports have linked computer contamination to colonization and infections in patients.850, 851 Although keyboard covers and washable keyboards that can be easily disinfected are available, the infection control benefit of these items and their optimal management have not yet been determined. In all health care settings, providing patients who are on Transmission-Based Precautions with dedicated noncritical medical equipment (eg, stethoscope, blood pressure cuff, electronic thermometer) has proven beneficial for preventing transmission.74, 89, 739, 852, 853 When this is not possible, disinfection of this equipment after each use is recommended. Other previously published guidelines should be consulted for detailed guidance in developing specific protocols for cleaning and reprocessing medical equipment and patient care items in both routine and special circumstances.11, 14, 18, 20, 739, 835, 847 In home care, it is preferable to remove visible blood or body fluids from durable medical equipment before it leaves the home. Equipment can be cleaned onsite using a detergent/disinfectant and, when possible, should be placed in a plastic bag for transport to the reprocessing location.20, 738 II.K. Textiles and Laundry Although soiled textiles, including bedding, towels, and patient or resident clothing, may be contaminated with pathogenic microorganisms, the risk of disease transmission is negligible if these textiles are handled, transported, and laundered in a safe manner.11, 854, 855 Key principles for handling soiled laundry are (1) avoiding shaking the items or handling them in any way that may aerosolize infectious agents, (2) avoiding contact of one's body and personal clothing with the soiled items being handled, and (3) containing soiled items in a laundry bag or designated bin. If a laundry chute is used, it must be maintained to minimize dispersion of aerosols from contaminated items. 11 Methods of handling, transporting, and laundering soiled textiles are determined by organizational policy and any applicable regulations; 738 guidance is provided in the Guidelines for Environmental Infection Control in Health Care Facilities. 11 Rather than rigid rules and regulations, hygienic and common sense storage and processing of clean textiles is recommended.11, 856 When laundering is done outside of a health care facility, the clean items must be packaged or completely covered and placed in an enclosed space during transport to prevent contamination with outside air or construction dust that could contain infectious fungal spores that pose a risk for immunocompromised patients. 11 Institutions are required to launder garments used as PPE and uniforms visibly soiled with blood or infective material. 738 Little data exist on the safety of home laundering of HCW uniforms, but no increase in infection rates was observed in the one published study, 857 and no pathogens were recovered from home- or hospital-laundered scrubs in another study. 858 In the home, textiles and laundry from patients with potentially transmissible infectious pathogens do not require special handling or separate laundering and may be washed with warm water and detergent.11, 857, 858 II.L. Solid Waste The management of solid waste emanating from the health care environment is subject to federal and state regulations for medical and nonmedical waste.859, 860 No additional precautions are needed for nonmedical solid waste removed from rooms of patients on Transmission-Based Precautions. Solid waste may be contained in a single bag of sufficient strength. 861 II.M. Dishware and Eating Utensils The combination of hot water and detergents used in dishwashers is sufficient to decontaminate dishware and eating utensils. Therefore, no special precautions are needed for dishware (eg, dishes, glasses, cups) or eating utensils. Reusable dishware and utensils may be used for patients requiring Transmission-Based Precautions. In the home and other communal settings, eating utensils and drinking vessels should not be shared, consistent with principles of good personal hygiene and to help prevent transmission of respiratory viruses, herpes simplex virus, and infectious agents that infect the gastrointestinal tract and are transmitted by the fecal/oral route (eg, hepatitis A virus, noroviruses). If adequate resources for cleaning utensils and dishes are not available, then disposable products may be used. II.N. Adjunctive Measures Important adjunctive measures that are not considered primary components of programs to prevent transmission of infectious agents but nonetheless improve the effectiveness of such programs include (1) antimicrobial management programs, (2) postexposure chemoprophylaxis with antiviral or antibacterial agents, (3) vaccines used both for pre-exposure and postexposure prevention, and (4) screening and restricting visitors with signs of transmissible infections. Detailed discussion of judicious use of antimicrobial agents is beyond the scope of this document; however, this topic has been addressed in a previous CDC guideline (http://www.cdc.gov/ncidod/dhqp/pdf/ar/mdroGuideline2006.pdf). II.N.1. Chemoprophylaxis Antimicrobial agents and topical antiseptics may be used to prevent infection and potential outbreaks of selected agents. Infections for which postexposure chemoprophylaxis is recommended under defined conditions include B pertussis,17, 862 N meningitides, 863 B anthracis after environmental exposure to aeosolizable material, 864 influenza virus, 610 HIV, 865 and group A streptococcus. 160 Orally administered antimicrobials also may be used under defined circumstances for MRSA decolonization of patients or HCWs. 866 Another form of chemoprophylaxis involves the use of topical antiseptic agents. For example, triple dye is routinely used on the umbilical cords of term newborns to reduce the risk of colonization, skin infections, and omphalitis caused by S aureus, including MRSA, and group A streptococcus.867, 868 Extension of the use of triple dye to low birth weight infants in a NICU was one component of a program that controlled a long-standing MRSA outbreak. 22 Topical antiseptics (eg, mupirocin) also are used for decolonization of HCWs or selected patients colonized with MRSA, as discussed in the MDRO guideline866, 869, 870, 871, 872 II.N.2. Immunoprophylaxis Certain immunizations recommended for susceptible HCWs have decreased the risk of infection and the potential for transmission in health care facilities.17, 873 The OSHA mandate requiring employers to offer HBV vaccination to HCWs has played a substantial role in the sharp decline in incidence of occupational HBV infection.777, 874 The routine administration of varicella vaccine to HCWs has decreased the need to place susceptible HCWs on administrative leave after exposure to patients with varicella. 774 In addition, reports of health care–associated transmission of rubella in obstetric clinics33, 875 and measles in acute care settings 34 demonstrate the importance of immunization of susceptible HCWs against childhood diseases. Many states have requirements for vaccination of HCWs for measles and rubella in the absence of evidence of immunity. Annual influenza vaccine campaigns targeted at patients and HCWs in LTCFs and acute care settings have been instrumental in preventing or limiting institutional outbreaks; consequently, increasing attention is being directed toward improving influenza vaccination rates in HCWs.35, 610, 689, 876, 877, 878 Transmission of B pertussis in health care facilities has been associated with large and costly outbreaks that include both HCWs and patients.17, 36, 41, 100, 682, 826, 879, 880 HCWs in close contact with infants with pertussis are at particularly high risk because of waning immunity and, until 2005, the absence of a vaccine appropriate for adults. But 2 acellular pertussis vaccines were licensed in the United States in 2005, 1 for use in individuals age 11 to 18 years and the other for use in those age 10 to 64 years. 881 Current Advisory Committee on Immunization Practices provisional recommendations include immunization of adolescents and adults, especially those in contact with infants under age 12 months and HCWs with direct patient contact.882, 883 Immunization of children and adults will help prevent the introduction of vaccine-preventable diseases into health care settings. The recommended immunization schedule for children is published annually in the January issues of the Morbidity and Mortality Weekly Report, with interim updates as needed.884, 885 An adult immunization schedule also is available for healthy adults and those with special immunization needs due to high-risk medical conditions. 886 Some vaccines are also used for postexposure prophylaxis of susceptible individuals, including varicella, 887 influenza, 610 hepatitis B, 777 and smallpox 225 vaccines.17, 873 In the future, administration of a newly developed S aureus conjugate vaccine (still under investigation) to selected patients may provide a novel method of preventing health care–associated S aureus (including MRSA) infections in high-risk groups (eg, hemodialysis patients and candidates for selected surgical procedures).888, 889 Immune globulin preparations also are used for postexposure prophylaxis of certain infectious agents under specified circumstances (eg, varicella-zoster virus, HBV, rabies, measles and hepatitis A virus17, 832, 873). The RSV monoclonal antibody preparation palivizumab may have contributed to controlling a nosocomial outbreak of RSV in one NICU, but there is insufficient evidence to support a routine recommendation for its use in this setting. 890 II.N.3. Management of Visitors II.N.3.a Visitors as Sources of Infection Visitors have been identified as the source of several types of HAIs (eg, pertussis,40, 41 M tuberculosis,42, 891 influenza and other respiratory viruses24, 43, 44, 372 and SARS21, 252, 253, 254). Effective methods for visitor screening in health care settings have not yet been studied, however. Visitor screening is especially important during community outbreaks of infectious diseases and for high-risk patient units. Sibling visits are often encouraged in birthing centers, postpartum rooms, pediatric inpatient units, PICUs, and residential settings for children; in hospital settings, a child visitor should visit only his or her own sibling. Screening of visiting siblings and other children before they are allowed into clinical areas is necessary to prevent the introduction of childhood illnesses and common respiratory infections. Screening may be passive, through the use of signs to alert family members and visitors with signs and symptoms of communicable diseases not to enter clinical areas. More active screening may include the completion of a screening tool or questionnaire to elicit information related to recent exposures or current symptoms. This information is reviewed by the facility staff, after which the visitor is either permitted to visit or is excluded. 832 Family and household members visiting pediatric patients with pertussis and tuberculosis may need to be screened for a history of exposure, as well as signs and symptoms of current infection. Potentially infectious visitors are excluded until they receive appropriate medical screening, diagnosis, or treatment. If exclusion is not considered to be in the best interest of the patient or family (ie, primary family members of critically or terminally ill patients), then the symptomatic visitor must wear a mask while in the health care facility and remain in the patient's room, avoiding exposure to others, especially in public waiting areas and the cafeteria. Visitor screening is used consistently on HSCT units.15, 43 However, considering the experience during the 2003 SARS outbreaks and the potential for pandemic influenza, developing effective visitor screening systems will be beneficial. 9 Education concerning respiratory hygiene/cough etiquette is a useful adjunct to visitor screening. II.N.3.b Use of Barrier Precautions by Visitors The use of gowns, gloves, and masks by visitors in health care settings has not been addressed specifically in the scientific literature. Some studies included the use of gowns and gloves by visitors in the control of MDROs but did not perform a separate analysis to determine whether their use by visitors had a measurable impact.892, 893, 894 Family members or visitors who are providing care to or otherwise are in very close contact with the patient (eg, feeding, holding) may also have contact with other patients and could contribute to transmission in the absence of effective barrier precautions. Specific recommendations may vary by facility or by unit and should be determined by the specific level of interaction. Part III: Precautions to Prevent Transmission of Infectious Agents There are 2 tiers of HICPAC/CDC precautions to prevent transmission of infectious agents, Standard Precautions and Transmission-Based Precautions. Standard Precautions are intended to be applied to the care of all patients in all health care settings, regardless of the suspected or confirmed presence of an infectious agent. Implementation of Standard Precautions constitutes the primary strategy for the prevention of health care–associated transmission of infectious agents among patients and HCWs. Transmission-Based Precautions are for patients who are known or suspected to be infected or colonized with infectious agents, including certain epidemiologically important pathogens, which require additional control measures to effectively prevent transmission. Because the infecting agent often is not known at the time of admission to a health care facility, Transmission-Based Precautions are used empirically, according to the clinical syndrome and the likely etiologic agents at the time, and then modified when the pathogen is identified or a transmissible infectious etiology is ruled out. Examples of this syndromic approach are presented in Table 2. The HICPAC/CDC Guidelines also include recommendations for creating a Protective Environment for allogeneic HSCT patients. The specific elements of Standard and Transmission-Based Precautions are discussed in Part II of this guideline. In Part III, the circumstances in which Standard Precautions, Transmission-Based Precautions, and a Protective Environment are applied are discussed. Table 4, Table 5 summarize the key elements of these sets of precautions III.A. Standard Precautions Standard Precautions combine the major features of Universal Precautions779, 895 and Body Substance Isolation 639 and are based on the principle that all blood, body fluids, secretions, excretions except sweat, nonintact skin, and mucous membranes may contain transmissible infectious agents. Standard Precautions include a group of infection prevention practices that apply to all patients, regardless of suspected or confirmed infection status, in any setting in which health care is delivered (Table 4). These include hand hygiene; use of gloves, gown, mask, eye protection, or face shield, depending on the anticipated exposure; and safe injection practices. Also, equipment or items in the patient environment likely to have been contaminated with infectious body fluids must be handled in a manner to prevent transmission of infectious agents (eg, wear gloves for direct contact, contain heavily soiled equipment, properly clean and disinfect or sterilize reusable equipment before use on another patient). The application of Standard Precautions during patient care is determined by the nature of the HCW–patient interaction and the extent of anticipated blood, body fluid, or pathogen exposure. For some interactions (eg, performing venipuncture), only gloves may be needed; during other interactions (eg, intubation), use of gloves, gown, and face shield or mask and goggles is necessary. Education and training on the principles and rationale for recommended practices are critical elements of Standard Precautions because they facilitate appropriate decision-making and promote adherence when HCWs are faced with new circumstances.654, 680, 681, 682, 683, 684, 685 An example of the importance of the use of Standard Precautions is intubation, especially under emergency circumstances when infectious agents may not be suspected, but later are identified (eg, SARS-CoV, N meningitides). The application of Standard Precautions is described below and summarized in Table 4. Guidance on donning and removing gloves, gowns and other PPE is presented in Figure 1. Standard Precautions are also intended to protect patients by ensuring that HCWs do not carry infectious agents to patients on their hands or via equipment used during patient care. III.A.1. New Elements of Standard Precautions Infection control problems that are identified in the course of outbreak investigations often indicate the need for new recommendations or reinforcement of existing infection control recommendations to protect patients. Because such recommendations are considered a standard of care and may not be included in other guidelines, they are added here to Standard Precautions. Three such areas of practice that have been added are respiratory hygiene/cough etiquette, safe injection practices, and use of masks for insertion of catheters or injection of material into spinal or epidural spaces through lumbar puncture procedures (eg, myelogram, spinal or epidural anesthesia). Although most elements of Standard Precautions evolved from Universal Precautions that were developed for protection of HCWs, these new elements of Standard Precautions focus on protection of patients. III.A.1.a Respiratory Hygiene/Cough Etiquette The transmission of SARS-CoV in emergency departments by patients and their family members during the widespread SARS outbreaks in 2003 highlighted the need for vigilance and prompt implementation of infection control measures at the first point of encounter within a health care setting (eg, reception and triage areas in emergency departments, outpatient clinics, and physician offices).21, 254, 896 The strategy proposed has been termed respiratory hygiene/cough etiquette9, 827 and is intended to be incorporated into infection control practices as a new component of Standard Precautions. The strategy is targeted at patients and accompanying family members and friends with undiagnosed transmissible respiratory infections, and applies to any person with signs of illness including cough, congestion, rhinorrhea, or increased production of respiratory secretions when entering a health care facility.40, 41, 43 The term cough etiquette is derived from recommended source control measures for M tuberculosis.12, 126 The elements of respiratory hygiene/cough etiquette include (1) education of health care facility staff, patients, and visitors; (2) posted signs, in language(s) appropriate to the population served, with instructions to patients and accompanying family members or friends; (3) source control measures (eg, covering the mouth/nose with a tissue when coughing and prompt disposal of used tissues, using surgical masks on the coughing person when tolerated and appropriate); (4) hand hygiene after contact with respiratory secretions; and (5) spatial separation, ideally >3 feet, of persons with respiratory infections in common waiting areas when possible. Covering sneezes and coughs and placing masks on coughing patients are proven means of source containment that prevent infected persons from dispersing respiratory secretions into the air.107, 145, 897, 898 Masking may be difficult in some settings, (eg, pediatrics), in which case the emphasis by necessity may be on cough etiquette. 899 Physical proximity of 1 year.27, 935, 936, 937 Likewise, available data indicate that colonization with VRE, MRSA, 938 and possibly MDR-GNB can persist for many months, especially in the presence of severe underlying disease, invasive devices, and recurrent courses of antimicrobial agents. It may be prudent to assume that MDRO carriers are colonized permanently and manage them accordingly. Alternatively, an interval free of hospitalizations, antimicrobial therapy, and invasive devices (eg, 6 or 12 months) before reculturing patients to document clearance of carriage may be used. Determination of the best strategy awaits the results of additional studies. See the 2006 HICPAC/CDC MDRO guideline 926 for a discussion of possible criteria to discontinue Contact Precautions for patients colonized or infected with MDROs. III.E. Application of Transmission-Based Precautions in Ambulatory and Home Care Settings Although Transmission-Based Precautions generally apply in all health care settings, exceptions exist. For example, in home care, AIIRs are not available. Furthermore, family members already exposed to diseases such as varicella and tuberculosis would not use masks or respiratory protection, but visiting HCWs would need to use such protection. Similarly, management of patients colonized or infected with MDROs may necessitate Contact Precautions in acute care hospitals and in some LTCFs when there is continued transmission, but the risk of transmission in ambulatory care and home care has not been defined. Consistent use of Standard Precautions may suffice in these settings, but more information is needed. III.F. Protective Environment A PE is designed for allogeneic HSCT patients to minimize fungal spore counts in the air and reduce the risk of invasive environmental fungal infections (see Table 5 for specifications).11, 13, 14, 15 The need for such controls has been demonstrated in studies of aspergillosis outbreaks associated with construction.11, 14, 15, 157, 158 As defined by the AIA 13 and presented in detail in the CDC's 2003 Guideline for Environmental Infection Control in Health Care Facilities,11, 860 air quality for HSCT patients is improved through a combination of environmental controls that include (1) HEPA filtration of incoming air, (2) directed room air flow, (3) positive room air pressure relative to the corridor, (4) well-sealed rooms (including sealed walls, floors, ceilings, windows, electrical outlets) to prevent flow of air from the outside, (5) ventilation to provide ≥ 12 air changes per hour, (6) strategies to minimize dust (eg, scrubbable surfaces rather than upholstery 939 and carpet, 940 and routinely cleaning crevices and sprinkler heads), and (7) prohibiting dried and fresh flowers and potted plants in the rooms of HSCT patients. The latter is based on molecular typing studies that have found indistinguishable strains of Aspergillus terreus in patients with hematologic malignancies and in potted plants in the vicinity of the patients.941, 942, 943 The desired quality of air may be achieved without incurring the inconvenience or expense of laminar airflow.15, 157 To prevent inhalation of fungal spores during periods when construction, renovation, or other dust-generating activities that may be ongoing in and around the health care facility, it has been recommended that severely immunocompromised patients wear a high-efficiency respiratory protection device (eg, an N95 respirator) when they leave the PE.11, 14, 944 The use of masks or respirators by HSCT patients when they are outside of the PE for prevention of environmental fungal infections in the absence of construction has not been evaluated. A PE does not include the use of barrier precautions beyond those indicated for Standard Precuations and Transmission-Based Precautions. No published reports support the benefit of placing patients undergoing solid organ transplantation or other immunocompromised patients in a PE. Part IV: Recommendations These recommendations are designed to prevent transmission of infectious agents among patients and HCWs in all settings where health care is delivered. As in other CDC/HICPAC guidelines, each recommendation is categorized on the basis of existing scientific data, theoretical rationale, applicability, and, when possible, economic impact. The CDC/HICPAC system for categorizing recommendations is as follows: Category IA. Strongly recommended for implementation and strongly supported by well-designed experimental, clinical, or epidemiologic studies. Category IB. Strongly recommended for implementation and supported by some experimental, clinical, or epidemiologic studies and a strong theoretical rationale. Category IC. Required for implementation, as mandated by federal and/or state regulation or standard. Category II. Suggested for implementation and supported by suggestive clinical or epidemiologic studies or a theoretical rationale. No recommendation; unresolved issue. Practices for which insufficient evidence or no consensus regarding efficacy exists. I. Administrative Responsibilities Health care organization administrators should ensure the implementation of recommendations specified in this section. I.A. Incorporate preventing transmission of infectious agents into the objectives of the organization's patient and occupational safety programs.542, 543, 544, 545, 560, 629, 625, 945 Category IB/IC I.B. Make preventing transmission of infectious agents a priority for the health care organization. Provide administrative support, including fiscal and human resources for maintaining infection control programs.433, 547, 548, 551, 558, 560, 561, 562, 563, 565, 661, 945 Category IB/IC I.B.1. Ensure that individuals with training in infection control are employed by or are available by contract to all health care facilities, so that the infection control program is managed by 1 or more qualified individuals.315, 551, 565, 572, 575, 574, 945, 946 Category IB/IC I.B.1.a. Determine the specific infection control full-time equivalents according to the scope of the infection control program, the complexity of the health care facility or system, the characteristics of the patient population, the unique or urgent needs of the facility and community, and proposed staffing levels based on survey results and recommendations from professional organizations.315, 433, 548, 551, 565, 568, 572, 574, 947, 948 Category IB I.B.2. Include prevention of HAIs as a determinant of bedside nurse staffing levels and composition, especially in high-risk units.417, 550, 582, 584, 585, 586, 587, 588, 589, 591, 592, 593, 594, 595, 596 Category IB I.B.3. Delegate authority to infection control personnel or their designees (eg, patient care unit charge nurses) for making infection control decisions concerning patient placement and assignment of Transmission-Based Precautions.433, 548, 856, 945 Category IC I.B.4. Involve infection control personnel in decisions on facility construction and design, determination of AIIR and PE capacity needs, and environmental assessments.11, 12, 13, 949, 950 Category IB/IC I.B.4.a. Provide ventilation systems required for a sufficient number of AIIRs (as determined by a risk assessment) and PEs in health care facilities that provide care to patients for whom such rooms are indicated, according to published recommendations.11, 12, 13, 15 Category IB/IC I.B.5. Involve infection control personnel in the selection and postimplementation evaluation of medical equipment and supplies and changes in practice that could affect the risk of HAI.951, 952 Category IC I.B.6. Ensure availability of human and fiscal resources to provide clinical microbiology laboratory support, including a sufficient number of medical technologists trained in microbiology, appropriate to the health care setting, for monitoring transmission of microorganisms, planning and conducting epidemiologic investigations, and detecting emerging pathogens. Identify resources for performing surveillance cultures, rapid diagnostic testing for viral and other selected pathogens, preparation of antimicrobial susceptibility summary reports, trend analysis, and molecular typing of clustered isolates (performed either onsite or in a reference laboratory) and use these resources according to facility-specific epidemiologic needs, in consultation with clinical microbiologists.552, 553, 597, 598, 602, 604, 605, 606, 608, 609, 611, 613, 614, 615, 616, 953 Category IB I.B.7. Provide human and fiscal resources to meet occupational health needs related to infection control (eg, HCWs immunization, postexposure evaluation and care, evaluation and management of HCWs with communicable infections.12, 17, 134, 689, 738, 878, 879, 880 Category IB/IC I.B.8. In all areas where health care is delivered, provide supplies and equipment necessary for the consistent observance of Standard Precautions, including hand hygiene products and PPE (eg, gloves, gowns, face and eye protection).558, 738, 945 Category IB/IC I.B.9. Develop and implement policies and procedures to ensure that reusable patient care equipment is cleaned and reprocessed appropriately before use on another patient.11, 87, 836, 954, 955, 956, 957, 958, 959 Category IA/IC I.C. Develop and implement processes to ensure oversight of infection control activities appropriate to the health care setting and assign responsibility for oversight of infection control activities to an individual or group within the health care organization that is knowledgeable about infection control.433, 548, 565 Category II I.D. Develop and implement systems for early detection and management (eg, use of appropriate infection control measures, including isolation precautions, PPE) of potentially infectious persons at initial points of patient encounter in outpatient settings (eg, triage areas, emergency departments, outpatient clinics, physician offices) and at the time of admission to hospitals and LTCFs.9, 122, 134, 253, 826 Category IB I.E. Develop and implement policies and procedures to limit patient visitation by persons with signs or symptoms of a communicable infection. Screen visitors to high-risk patient care areas (eg, oncology units, HSCT units, intensive care units, other severely immunocompromised patients) for possible infection.24, 41, 43, 960, 961 Category IB I.F. Identify performance indicators of the effectiveness of organization-specific measures to prevent transmission of infectious agents (Standard Precautions and Transmission-Based Precautions), establish processes to monitor adherence to those performance measures, and provide feedback to staff members.554, 665, 666, 667, 703, 704, 739, 962 Category IB II. Education and Training II.A. Provide job- or task-specific education and training on preventing transmission of infectious agents associated with health care during orientation to the health care facility; update information periodically during ongoing education programs. Target all HCWs for education and training, including but not limited to medical, nursing, clinical technicians, and laboratory staff; property service (housekeeping), laundry, maintenance and dietary workers; students; contract staff; and volunteers. Document competency initially and repeatedly, as appropriate, for the specific staff positions. Develop a system to ensure that HCWs employed by outside agencies meet these education and training requirements through programs offered by the agencies or by participation in the health care facility's program designed for full-time personnel.126, 558, 560, 561, 654, 680, 681, 682, 683, 685, 687, 688, 701, 892, 918, 963 Category IB II.A.1. Include in education and training programs, information concerning use of vaccines as an adjunctive infection control measure.17, 610, 689, 873 Category IB II.A.2. Enhance education and training by applying principles of adult learning, using reading level and language appropriate material for the target audience, and using online educational tools available to the institution.657, 693, 694, 696, 697, 699, 964 Category IB II.B. Provide instructional materials for patients and visitors on recommended hand hygiene and respiratory hygiene/cough etiquette practices and the application of Transmission-Based Precautions.9, 708, 709, 961 Category II III. Surveillance III.A. Monitor the incidence of epidemiologically important organisms and targeted HAIs that have a substantial impact on outcome and for which effective preventive interventions are available. Use information collected through surveillance of high-risk populations, procedures, devices, and highly transmissible infectious agents to detect transmission of infectious agents in the health care facility.565, 670, 671, 672, 674, 686, 918, 965, 966, 967, 968 Category IA III.B. Apply the following epidemiologic principles of infection surveillance:662, 663, 670, 672, 965, 967 Category IB • Use standardized definitions of infection. • Use laboratory-based data (when available). • Collect epidemiologically important variables (eg, patient locations and/or clinical service in hospitals and other large multiunit facilities, population-specific risk factors [eg, low birth weight neonates], underlying conditions that predispose to serious adverse outcomes). • Analyze data to identify trends that may indicated increased rates of transmission. • Feedback information on trends in the incidence and prevalence of HAIs, probable risk factors, and prevention strategies and their impact to the appropriate health care providers, organization administrators, and as required by local and state health authorities. III.C. Develop and implement strategies to reduce risks for transmission and evaluate effectiveness565, 672, 683, 961, 968, 969 Category IB III.D. When transmission of epidemiologically important organisms continues despite implementation and documented adherence to infection prevention and control strategies, obtain consultation from persons knowledgeable in infection control and health care epidemiology to review the situation and recommend additional measures for control.247, 566, 686 Category IB III.E. Periodically review information on community or regional trends regarding the incidence and prevalence of epidemiologically important organisms (eg, influenza, RSV, pertussis, invasive group A streptococcal disease, MRSA, VRE) (including in other health care facilities) that may affect transmission of organisms within the facility.397, 686, 970, 971, 972 Category II IV. Standard Precautions Assume that every person is potentially infected or colonized with an organism that could be transmitted in the health care setting and apply the following infection control practices during the delivery of health care. IV.A. Hand Hygiene IV.A.1. During the delivery of health care, avoid unnecessary touching of surfaces in close proximity to the patient to prevent both contamination of clean hands from environmental surfaces and transmission of pathogens from contaminated hands to surfaces.72, 73, 738, 799, 973 {CDC, 2001 #970. Category IB/IC IV.A.2. When hands are visibly dirty, contaminated with proteinaceous material, or visibly soiled with blood or body fluids, wash hands with either a nonantimicrobial soap and water or an antimicrobial soap and water. 558 Category IA IV.A.3. If hands are not visibly soiled, or after removing visible material with nonantimicrobial soap and water, decontaminate hands in the clinical situations described in IV.A.2.a–f. The preferred method of hand decontamination is with an alcohol-based hand rub.561, 974 Alternatively, hands may be washed with an antimicrobial soap and water. Frequent use of an alcohol-based hand rub immediately after handwashing with nonantimicrobial soap may increase the frequency of dermatitis. 558 Category IB Perform hand hygiene: IV.A.3.a. Before having direct contact with patients.663, 975 Category IB IV.A.3.b. After contact with blood, body fluids or excretions, mucous membranes, nonintact skin, or wound dressings. 663 Category IA IV.A.3.c. After contact with a patient's intact skin (eg, when measuring pulse or blood pressure or lifting a patient).167, 976, 977, 978 Category IB IV.A.3.d. If hands will be moving from a contaminated body site to a clean body site during patient care. Category II IV.A.3.e. After contact with inanimate objects (including medical equipment) in the immediate vicinity of the patient.72, 73, 88, 799, 979, 980 Category II IV.A.3.f. After removing gloves.727, 740, 741 Category IB IV.A.4. Wash hands with nonantimicrobial soap and water or with antimicrobial soap and water if contact with spores (eg, C difficile or B anthracis) is likely to have occurred. The physical action of washing and rinsing hands under such circumstances is recommended because alcohols, chlorhexidine, iodophors, and other antiseptic agents have poor activity against spores.558, 954, 981 Category II IV.A.5. Do not wear artificial fingernails or extenders if duties include direct contact with patients at high risk for infection and associated adverse outcomes (eg, those in ICUs or operating rooms).30, 31, 558, 721, 722, 723 Category IA IV.A.5.a. Develop an organizational policy on the wearing of nonnatural nails by HCWs who have direct contact with patients outside of the groups specified above. 982 Category II IV.B. Personal protective equipment (see Fig 1) IV.B.1. Observe the following principles of use: IV.B.1.a. Wear PPE, as described in IV.B.2–4, when the nature of the anticipated patient interaction indicates that contact with blood or body fluids may occur.738, 779, 895 Category IB/IC IV.B.1.b. Prevent contamination of clothing and skin during the process of removing PPE (see Fig 1). Category II IV.B.1.c. Before leaving the patient's room or cubicle, remove and discard PPE.18, 738 Category IB/IC IV.B.2. Gloves IV.B.2.a. Wear gloves when it can be reasonably anticipated that contact with blood or other potentially infectious materials, mucous membranes, nonintact skin, or potentially contaminated intact skin (eg, of a patient incontinent of stool or urine) could occur.18, 727, 738, 740, 779, 983 Category IB/IC IV.B.2.b. Wear gloves with fit and durability appropriate to the task.558, 730, 731, 738, 984, 985 Category IB IV.B.2.b.i. Wear disposable medical examination gloves for providing direct patient care. IV.B.2.b.ii. Wear disposable medical examination gloves or reusable utility gloves for cleaning the environment or medical equipment. IV.B.2.c. Remove gloves after contact with a patient and/or the surrounding environment (including medical equipment) using proper technique to prevent hand contamination (see Fig 1). Do not wear the same pair of gloves for the care of more than 1 patient. Do not wash gloves for the purpose of reuse, because this practice has been associated with transmission of pathogens.558, 727, 740, 741, 742, 986 Category IB IV.B.2.d. Change gloves during patient care if the hands will move from a contaminated body site (eg, perineal area) to a clean body site (eg, face). Category II IV.B.3. Gowns IV.B.3.a. Wear a gown appropriate to the task to protect skin and prevent soiling or contamination of clothing during procedures and patient care activities when contact with blood, body fluids, secretions, or excretions is anticipated.738, 779, 894 Category IB/IC IV.B.3.a.i. Wear a gown for direct patient contact if the patient has uncontained secretions or excretions.24, 88, 89, 738, 743 Category IB/IC IV.B.3.a.ii. Remove gown and perform hand hygiene before leaving the patient's environment.24, 88, 89, 738, 743 Category IB/IC IV.B.3.b. Do not reuse gowns, even for repeated contacts with the same patient. Category II IV.B.3.c. Routine donning of gowns on entrance into a high-risk unit (eg, ICU, NICU, HSCT unit) is not indicated.364, 746, 747, 748, 749 Category IB IV.B.4. Mouth, nose, and eye protection IV.B.4.a. Use PPE to protect the mucous membranes of the eyes, nose, and mouth during procedures and patient care activities that are likely to generate splashes or sprays of blood, body fluids, secretions, and excretions. Select masks, goggles, face shields, and combinations of these according to the need anticipated by the task to be performed.113, 738, 779, 895 Category IB/IC IV.B.5. During aerosol-generating procedures (eg, bronchoscopy, suctioning of the respiratory tract [if not using in-line suction catheters], endotracheal intubation) in patients who are not suspected of being infected with an agent for which respiratory protection is otherwise recommended (eg, M tuberculosis, SARS, or hemorrhagic fever viruses), wear one of the following: a face shield that fully covers the front and sides of the face, a mask with attached shield, or a mask and goggles (in addition to gloves and gown).93, 94, 95, 96, 113, 126, 134 Category IB IV.C. Respiratory hygiene/cough etiquette IV.C.1. Educate HCWs on the importance of source control measures to contain respiratory secretions, to prevent droplet and fomite transmission of respiratory pathogens, especially during seasonal outbreaks of viral respiratory tract infections (eg, influenza, RSV, adenovirus, parainfluenza virus) in communities.10, 14, 24, 261, 683 Category IB IV.C.2. Implement the following measures to contain respiratory secretions in patients and accompanying individuals who have signs and symptoms of a respiratory infection, beginning at the point of initial encounter in a health care setting (eg, triage, reception and waiting areas in emergency departments, outpatient clinics, and physicians' offices).20, 24, 145, 901, 987 IV.C.2.a. Post signs at entrances and in strategic places (eg, elevators, cafeterias) within ambulatory and inpatient settings with instructions to patients and other persons with symptoms of respiratory infection to cover their mouths and noses when coughing or sneezing, use and dispose of tissues, and perform hand hygiene after hands have been in contact with respiratory secretions. Category II IV.C.2.b. Provide tissues and no-touch receptacles (eg, foot pedal–operated lid or open, plastic-lined wastebasket) for disposal of tissues. 20 Category II IV.C.2.c. Provide resources and instructions for performing hand hygiene in or near waiting areas in ambulatory and inpatient settings; provide conveniently located dispensers of alcohol-based hand rubs and, where sinks are available, supplies for handwashing.558, 901 Category IB IV.C.2.d. During periods of increased prevalence of respiratory infections in the community (as indicated by, eg, increased school absenteeism, increased number of patients seeking care for respiratory infection), offer masks to coughing patients and other symptomatic persons (eg, persons who accompany ill patients) on entry into the facility or medical office126, 898, 899 and encourage them to maintain special separation (ideally, at least 3 feet) from others in common waiting areas.20, 23, 103, 111, 114, 134 Category IB IV.C.2.d.i. Some facilities may find it logistically easier to institute this recommendation year-round as a standard of practice. Category II IV.D. Patient placement IV.D.1. Include the potential for transmission of infectious agents in patient placement decisions. Place patients who pose a risk for transmission to others (eg, those with uncontained secretions, excretions, or wound drainage; infants with suspected viral respiratory or gastrointestinal infections) in a single-patient room when available.24, 409, 429, 434, 792, 795, 796, 805, 988 Category IB IV.D.2. Determine patient placement based on the following factors: • Route(s) of transmission of the known or suspected infectious agent • Risk factors for transmission in the infected patient • Risk factors for adverse outcomes resulting from an HAI in other patients in the area or room being considered for patient placement • Availability of single-patient rooms • Patient options for room sharing (eg, cohorting patients with the same infection) Category II IV.E. Patient care equipment and instruments/devices 954 IV.E.1. Establish policies and procedures for containing, transporting, and handling patient care equipment and instruments/devices that may be contaminated with blood or body fluids18, 738, 973 Category IB/IC IV.E.2. Remove organic material from critical and semicritical instrument/devices, using recommended cleaning agents before high-level disinfection and sterilization to enable effective disinfection and sterilization processes.835, 989, 990 Category IA IV.E.3. Wear PPE (eg, gloves, gown), according to the level of anticipated contamination, when handling patient care equipment and instruments/devices that is visibly soiled or may have been in contact with blood or body fluids.18, 738, 973 Category IB/IC IV.F. Care of the environment 11 IV.F.1. Establish policies and procedures for routine and targeted cleaning of environmental surfaces as indicated by the level of patient contact and degree of soiling. 11 Category II IV.F.2. Clean and disinfect surfaces likely to be contaminated with pathogens, including those in close proximity to the patient (eg, bed rails, over bed tables) and frequently touched surfaces in the patient care environment (eg, door knobs, surfaces in and surrounding toilets in patient rooms) on a more frequent schedule compared with that for other surfaces (eg, horizontal surfaces in waiting rooms).11, 72, 73, 739, 745, 799, 833, 991, 992, 993 Category IB IV.F.3. Use EPA-registered disinfectants that have microbiocidal (ie, killing) activity against the pathogens most likely to contaminate the patient care environment. Use in accordance with manufacturer's instructions.841, 842, 843, 954, 994 Category IB/IC IV.F.3.a. Review the efficacy of disinfectants in use when evidence of continuing transmission of an infectious agent (eg, rotavirus, C difficile, norovirus) may indicate resistance to the product and a change to a more effective disinfectant as indicated.274, 841, 846 Category II IV.F.4. In facilities that provide health care to pediatric patients or that have waiting areas with children's toys (eg, obstetric/gynecology offices and clinics), establish policies and procedures for cleaning and disinfecting toys at regular intervals.80, 378 Category IB Consider the following principles when developing this policy and procedures: Category II • Select play toys that can be easily cleaned and disinfected. • Do not permit use of stuffed furry toys if they will be shared. • Clean and disinfect large stationary toys (eg, climbing equipment) at least weekly and whenever visibly soiled. • If toys are likely to be mouthed, rinse with water after disinfection; alternatively, wash in a dishwasher. • When a toy requires cleaning and disinfection, do so immediately or store in a designated labeled container separate from toys that are clean and ready for use. IV.F.5. Include multiuse electronic equipment in policies and procedures for preventing contamination and for cleaning and disinfection, especially those items that are used by patients, those used during delivery of patient care, and mobile devices that are moved in and out of patient rooms frequently (eg, daily).849, 850, 851, 995 Category IB IV.F.5.a. No recommendation for use of removable protective covers or washable keyboards. Unresolved issue IV.G. Textiles and laundry IV.G.1. Handle used textiles and fabrics with minimum agitation to avoid contamination of air, surfaces, and persons.738, 996, 997 Category IB/IC IV.G.2. If laundry chutes are used, ensure that they are properly designed, maintained, and used in a manner to minimize dispersion of aerosols from contaminated laundry.11, 13, 998, 999 Category IB/IC IV.H. Safe injection practices The following recommendations apply to the use of needles, cannulas that replace needles, and, where applicable, intravenous delivery systems: 453 IV.H.1. Use aseptic technique to avoid contamination of sterile injection equipment1000, 1001 Category IA IV.H.2. Do not administer medications from a syringe to multiple patients, even if the needle or cannula on the syringe is changed. Needles, cannulae, and syringes are sterile, single-use items; they should not be reused for another patient or to access a medication or solution that might be used for a subsequent patient.452, 918, 1002, 1003 Category IA IV.H.3. Use fluid infusion and administration sets (ie, intravenous bags, tubing and connectors) for one patient only and dispose of appropriately after use. Consider a syringe or needle/cannula to be contaminated once it has been used to enter or connect to a patient's intravenous infusion bag or administration set. 452 Category IB IV.H.4. Use single-dose vials for parenteral medications whenever possible. 452 Category IA IV.H.5. Do not administer medications from single-dose vials or ampules to multiple patients or combine leftover contents for later use.368, 452, 1003 Category IA IV.H.6. If multidose vials must be used, both the needle or cannula and syringe used to access the multidose vial must be sterile.452, 1000 Category IA IV.H.7. Do not keep multidose vials in the immediate patient treatment area. Store in accordance with the manufacturer's recommendations; discard if sterility is compromised or questionable.452, 1001 Category IA IV.H.8. Do not use bags or bottles of intravenous solution as a common source of supply for multiple patients.452, 1004 Category IB IV.I. Infection control practices for special lumbar puncture procedures Wear a surgical mask when placing a catheter or injecting material into the spinal canal or subdural space (ie, during myelograms, lumbar puncture and spinal or epidural anesthesia).904, 905, 906, 907, 908, 909, 910, 911, 912, 916, 1005 Category IB IV.J. Worker safety Adhere to federal and state requirements for protection of HCWs from exposure to bloodborne pathogens. 738 Category IC V. Transmission-Based Precautions V.A. General principles V.A.1. In addition to Standard Precautions, use Transmission-Based Precautions for patients with documented or suspected infection or colonization with highly transmissible or epidemiologically important pathogens for which additional precautions are needed to prevent transmission (see Appendix A).24, 93, 126, 141, 305, 805, 1006 Category IA V.A.2. Extend the duration of Transmission-Based Precautions, (eg, Droplet, Contact) for immunosuppressed patients with viral infections due to prolonged shedding of viral agents that may be transmitted to others.927, 930, 931, 932, 1007, 1008, 1009 Category IA V.B. Contact Precautions V.B.1. Use Contact Precautions as recommended in Appendix A for patients with known or suspected infections or evidence of syndromes that represent an increased risk for contact transmission. For specific recommendations for use of Contact Precautions for colonization or infection with MDROs, consult the MDRO guideline, available at http://www.cdc.gov/ncidod/dhqp/pdf/ar/mdroGuideline2006.pdf. 869 V.B.2. Patient placement V.B.2.a. In acute care hospitals, place patients who require Contact Precautions in a single-patient room when available.24, 686, 792, 795, 796, 805, 836, 892, 1010, 1011 Category IB V.B.2.b. When single-patient rooms are in short supply, apply the following principles for making decisions on patient placement: • Prioritize patients with conditions that may facilitate transmission (eg, uncontained drainage, stool incontinence) for single-patient room placement. Category II • Place patients who are infected or colonized with the same pathogen and are suitable roommates together in the same room (cohort).29, 637, 807, 810, 811, 812, 814, 817, 818 Category IB • If it becomes necessary to place a patient requiring Contact Precautions in a room with a patient who is not infected or colonized with the same infectious agent: - Avoid placing patients on Contact Precautions in the same room with patients who have conditions that may increase the risk of adverse outcome from infection or that may facilitate transmission (eg, those who are immunocompromised, have open wounds, or have anticipated prolonged lengths of stay). Category II - Ensure that patients are physically separated (ie, >3 feet apart) from each other. Draw the privacy curtain between beds to minimize opportunities for direct contact. Category II - Change protective attire and perform hand hygiene between contact with patients in the same room, regardless of whether or not either of the patients is on Contact Precautions.727, 740, 741, 986, 1012, 1013 Category IB V.B.2.c. In long-term care and other residential settings, make decisions regarding patient placement on a case-by-case basis, balancing infection risks to other patients in the room, the presence of risk factors that increase the likelihood of transmission, and the potential adverse psychological impact on the infected or colonized patient.919, 920 Category II V.B.2.d. In ambulatory settings, place patients who require Contact Precautions in an examination room or cubicle as soon as possible. 20 Category II V.B.3. Use of PPE V.B.3.a. Gloves Wear gloves whenever touching the patient's intact skin24, 89, 134, 558, 745, 836 or surfaces and articles in close proximity to the patient (eg, medical equipment, bed rails).72, 73, 88, 836 Don gloves on entry into the room or cubicle. Category IB V.B.3.b. Gowns V.B.3.b.i. Wear a gown whenever it is anticipated that clothing will come in direct contact with the patient or potentially contaminated environmental surfaces or equipment in close proximity to the patient. Don a gown on entry into the room or cubicle. Remove the gown and observe hand hygiene before leaving the patient care environment.24, 88, 134, 744, 836 Category IB V.B.3.b.ii. After gown removal, ensure that clothing and skin do not contact potentially contaminated environmental surfaces that could result in possible transfer of microorganism to other patients or environmental surfaces.72, 73 Category II V.B.4. Patient transport V.B.4.a. In acute care hospitals and long-term care and other residential settings, limit transport and movement of patients outside of the room to medically necessary purposes. Category II V.B.4.b. When transport or movement in any health care setting is necessary, ensure that infected or colonized areas of the patient's body are contained and covered. Category II V.B.4.c. Remove and dispose of contaminated PPE and perform hand hygiene before transporting patients on Contact Precautions. Category II V.B.4.d. Don clean PPE to handle the patient at the transport destination. Category II V.B.5. Patient care equipment and instruments/devices V.B.5.a. Handle patient care equipment and instruments/devices according to Standard Precautions.738, 835 Category IB/IC V.B.5.b. In acute care hospitals and long-term care and other residential settings, use disposable noncritical patient care equipment (eg, blood pressure cuffs) or implement patient-dedicated use of such equipment. If common use of equipment for multiple patients is unavoidable, clean and disinfect such equipment before use on another patient.24, 88, 795, 835, 836, 853, 1014 Category IB V.B.5.c. In-home care settings V.B.5.c.i. Limit the amount of nondisposable patient care equipment brought into the home of a patient on Contact Precautions. Whenever possible, leave patient care equipment in the home until discharge from home care services. Category II V.B.5.c.ii. If noncritical patient care equipment (eg, stethoscope) cannot remain in the home, clean and disinfect items before taking them from the home using a low- to intermediate-level disinfectant. Alternatively, place contaminated reusable items in a plastic bag for transport and subsequent cleaning and disinfection. Category II V.B.5.d. In ambulatory settings, place contaminated reusable noncritical patient care equipment in a plastic bag for transport to a soiled utility area for reprocessing. Category II V.B.6. Environmental measures Ensure that rooms of patients on Contact Precautions are prioritized for frequent cleaning and disinfection (eg, at least daily) with a focus on frequently touched surfaces (eg, bed rails, overbed table, bedside commode, lavatory surfaces in patient bathrooms, doorknobs) and equipment in the immediate vicinity of the patient.11, 24, 88, 745, 836 Category IB V.B.7. Discontinue Contact Precautions after signs and symptoms of the infection have resolved or according to pathogen-specific recommendations in Appendix A. Category IB V.C. Droplet Precautions V.C.1. Use Droplet Precautions as recommended in Appendix A for patients known or suspected infection with pathogens transmitted by respiratory droplets (ie, droplets > 5 μ) generated by a patient who is coughing, sneezing, or talking,14, 23, Steinberg, 1969 #1708,41, 95, 103, 111, 112, 754, 755, 987, 1015 Category IB V.C.2. Patient placement V.C.2.a. In acute care hospitals, place patients who require Droplet Precautions in a single-patient room when available Category II When single-patient rooms are in short supply, apply the following principles when making decisions on patient placement: • Prioritize patients who have excessive cough and sputum production for single-patient room placement. Category II • Place patients who are infected the same pathogen and are suitable roommates together in the same room (cohort).813, 815 Category IB • If it becomes necessary to place patients who require Droplet Precautions in a room with a patient who does not have the same infection: - Avoid placing patients on Droplet Precautions in the same room with patients who have conditions that may increase the risk of adverse outcome from infection or that may facilitate transmission (eg, those who are immunocompromised or have anticipated prolonged lengths of stay). Category II - Ensure that patients are physically separated (ie, >3 feet apart) from each other. Draw the privacy curtain between beds to minimize opportunities for close contact.103, 104, 409 Category IB - Change protective attire and perform hand hygiene between contact with patients in the same room, regardless of whether or not either patient is on Droplet Precautions.740, 741, 986, 1012, 1013 Category IB V.C.2.b. In long-term care and other residential settings, make decisions regarding patient placement on a case-by-case basis after considering infection risks to other patients in the room and available alternatives. 409 Category II V.C.2.c. In ambulatory settings, place patients who require Droplet Precautions in an examination room or cubicle as soon as possible. Instruct patients to follow recommendations for respiratory hygiene/cough etiquette.9, 446, 447, 827 Category II V.C.3. Use of PPE V.C.3.a. Don a mask on entry into the patient's room or cubicle.14, 23, 41, 103, 111, 113, 115, 826 Category IB V.C.3.b. No recommendation for routinely wearing eye protection (eg, goggle or face shield) in addition to a mask, for close contact with patients who require Droplet Precautions. Unresolved issue V.C.3.c. For patients with suspected or proven SARS, avian influenza or pandemic influenza, refer to the following websites for the most current recommendations: http://www.cdc.gov/ncidod/sars/; http://www.cdc.gov/flu/avian/; and http://www.pandemicflu.gov/.134, 1016, 1017 V.C.4. Patient transport V.C.4.a. In acute care hospitals and long-term care and other residential settings, limit transport and movement of patients outside of the room to medically necessary purposes. Category II V.C.4.b. If transport or movement in any health care setting is necessary, instruct the patient to wear a mask and follow respiratory hygiene/cough etiquette (see http://www.cdc.gov/flu/professionals/infectioncontrol/resphygiene.htm). Category IB V.C.4.c. No mask is required for persons transporting patients on Droplet Precautions. Category II V.C.4.d. Discontinue Droplet Precautions after signs and symptoms have resolved or according to pathogen-specific recommendations in Appendix A. Category IB V.D. Airborne Precautions V.D.1. Use Airborne Precautions as recommended in Appendix A for patients known or suspected to be infected with infectious agents transmitted person to person by the airborne route (eg, M tuberculosis, 12 measles,34, 122, 1018 chickenpox,123, 772, 1019 disseminated herpes zoster 1020 ). Category IA/IC V.D.2. Patient placement V.D.2.a. In acute care hospitals and long-term care settings, place patients who require Airborne Precautions in an AIIR that has been constructed in accordance with current guidelines.11, 12, 13 Category IA/IC V.D.2.a.i. Provide at least 6 (in an existing facility) or 12 (in new construction/renovation) air changes per hour. V.D.2.a.ii. Direct exhaust of air to the outside. If it is not possible to exhaust air from an AIIR directly to the outside, the air may be returned to the air-handling system or adjacent spaces if all air is directed through HEPA filters. V.D.2.a.iii. Whenever an AIIR is in use for a patient on Airborne Precautions, monitor air pressure daily with visual indicators (eg, smoke tubes, flutter strips), regardless of the presence or absence of differential pressure-sensing devices (eg, manometers).11, 12, 1021, 1022 V.D.2.a.iv. Keep the AIIR door closed when not required for entry and exit. V.D.2.b. When an AIIR is not available, transfer the patient to a facility that has an available AIIR. 12 Category II V.D.2.c. In the event of an outbreak or exposure involving large numbers of patients who require Airborne Precautions: • Consult an ICP before patient placement to determine the safety of an alternative room that does not meet engineering requirements for an AIIR. • Place patients who are presumed to have the same infection (based on clinical presentation and diagnosis when known) together (cohort) in areas of the facility away from other patients, especially patients at increased risk for infection (eg, immunocompromised patients). • Use temporary portable solutions (eg, exhaust fan) to create a negative-pressure environment in the converted area of the facility. Discharge air directly to the outside, away from people and air intakes, or direct all of the air through HEPA filters before it is introduced to other air spaces. 12 Category II V.D.2.d. In ambulatory settings: V.D.2.d.i. Develop systems (eg, triage, signage) to identify patients with known or suspected infections who require Airborne Precautions on entry into ambulatory settings.9, 12, 34, 127, 134 Category IA V.D.2.d.ii. Place the patient in an AIIR as soon as possible. If an AIIR is not available, place a surgical mask on the patient and place the patient in an examination room. Once the patient leaves, the room should remain vacant for the appropriate time (generally 1 hour) to allow for a full exchange of air.11, 12, 122 Category IB/IC V.D.2.d.iii. Instruct a patient with a known or suspected airborne infection to wear a surgical mask and observe respiratory hygiene/cough etiquette. Once in an AIIR, the mask may be removed; the mask should remain on if the patient is not in an AIIR.12, 107, 145, 898 Category IB/IC V.D.3. Personnel restrictions Restrict susceptible HCWs from entering the rooms of patients known or suspected to have measles (rubeola), varicella (chickenpox), disseminated zoster, or smallpox if other immune HCWs are available.17, 774 Category IB V.D.4. Use of PPE V.D.4.a. Wear a fit-tested NIOSH-approved N95 or higher-level respirator for respiratory protection when entering the room or home of a patient when the following diseases are suspected or confirmed: • Infectious pulmonary or laryngeal tuberculosis, or when infectious tuberculosis skin lesions are present and procedures that would aerosolize viable organisms (eg, irrigation, incision and drainage, whirlpool treatments) are performed.12, 1023, 1024 Category IB • Smallpox (vaccinated and unvaccinated). Respiratory protection is recommended for all HCWs, including those with a documented “take” after smallpox vaccination due to the risk of a genetically engineered virus against which the vaccine may not provide protection, or of exposure to a very large viral load (from, eg, high-risk aerosol-generating procedures, immunocompromised patients, hemorrhagic or flat smallpox).108, 129 Category II V.D.4.b. No recommendation is made regarding the use of PPE by HCWs who are presumed to be immune to measles (rubeola) or varicella-zoster based on history of disease, vaccine, or serologic testing when caring for an individual with known or suspected measles, chickenpox, or disseminated zoster due to difficulties in establishing definite immunity.1025, 1026 Unresolved issue V.D.4.c. No recommendation is made regarding the type of PPE (ie, surgical mask or respiratory protection with a N95 or higher-level respirator) to be worn by susceptible HCWs who must have contact with patients with known or suspected measles, chickenpox, or disseminated herpes zoster. Unresolved issue V.D.5. Patient transport V.D.5.a. In acute care hospitals and long-term care and other residential settings, limit transport and movement of patients outside of the room to medically necessary purposes. Category II V.D.5.b. If transport or movement outside an AIIR is necessary, instruct the patient to wear a surgical mask, if possible, and to observe respiratory hygiene/cough etiquette. 12 Category II V.D.5.c. For a patient with skin lesions associated with varicella or smallpox or draining skin lesions caused by M tuberculosis, cover the affected areas to prevent aerosolization or contact with the infectious agent in skin lesions.108, 1023, 1024, 1027, 1028, 1029 Category IB V.D.5.d. An HCW transporting a patient on Airborne Precautions does not need to wear a mask or respirator during transport if the patient is wearing a mask and infectious skin lesions are covered. Category II V.D.6. Exposure management Immunize or provide the appropriate immune globulin to susceptible persons as soon as possible after unprotected contact (ie, exposure) to a patient with measles, varicella, or smallpox: Category IA • Administer measles vaccine to exposed susceptible persons within 72 hours after the exposure or administer immune globulin within 6 days of the exposure event for high-risk persons in whom vaccine is contraindicated.17, 1030, 1031, 1032, 1033 • Administer varicella vaccine to exposed susceptible persons within 120 hours after the exposure or administer varicella immune globulin (VZIG or an alternative product), when available, within 96 hours for high-risk persons in whom vaccine is contraindicated (eg, immunocompromised patients, pregnant women, newborns whose mother's varicella onset was 99.97% of particles > 0.3 μm (the most penetrating particle size) at a specified flow rate of air. HEPA filters may be integrated into the central air handling systems, installed at the point of use above the ceiling of a room, or used as portable units (MMWR 2003; 52: RR-10). Home care. A wide range of medical, nursing, rehabilitation, hospice, and social services delivered to patients in their place of residence (eg, private residence, senior living center, assisted living facility). Home health care services include care provided by home health aides and skilled nurses, respiratory therapists, dieticians, physicians, chaplains, and volunteers; provision of durable medical equipment; home infusion therapy; and physical, speech, and occupational therapy. Immunocompromised patient. A patient whose immune mechanisms are deficient because of a congenital or acquired immunologic disorder (eg, human immunodeficiency virus infection, congenital immune deficiency syndromes), chronic diseases such as diabetes mellitus, cancer, emphysema, or cardiac failure, intensive care unit care, malnutrition, and immunosuppressive therapy of another disease process [eg, radiation, cytotoxic chemotherapy, anti–graft rejection medication, corticosteroids, monoclonal antibodies directed against a specific component of the immune system]). The type of infections for which an immunocompromised patient has increased susceptibility is determined by the severity of immunosuppression and the specific component(s) of the immune system that is affected. Patients undergoing allogeneic hematopoietic stem cell transplantation and those with chronic graft versus host disease are considered the most vulnerable to health care–associated infections. Immunocompromised states also make it more difficult to diagnose certain infections (eg, tuberculosis) and are associated with more severe clinical disease states than persons with the same infection and a normal immune system. Infection. The transmission of microorganisms into a host after evading or overcoming defense mechanisms, resulting in the organism's proliferation and invasion within host tissue(s). Host responses to infection may include clinical symptoms or may be subclinical, with manifestations of disease mediated by direct organisms pathogenesis and/or a function of cell-mediated or antibody responses that result in the destruction of host tissues. Infection control and prevention professional (ICP). A person whose primary training is in either nursing, medical technology, microbiology, or epidemiology and who has acquired specialized training in infection control. Responsibilities may include collection, analysis, and feedback of infection data and trends to health care providers; consultation on infection risk assessment, prevention, and control strategies; performance of education and training activities; implementation of evidence-based infection control practices or those mandated by regulatory and licensing agencies; application of epidemiologic principles to improve patient outcomes; participation in planning renovation and construction projects (eg, to ensure appropriate containment of construction dust); evaluation of new products or procedures on patient outcomes; oversight of employee health services related to infection prevention; implementation of preparedness plans; communication within the health care setting, with local and state health departments, and with the community at large concerning infection control issues; and participation in research. Certification in infection control is available through the Certification Board of Infection Control and Epidemiology. Infection control and prevention program. A multidisciplinary program that includes a group of activities to ensure that recommended practices for the prevention of health care–associated infections are implemented and followed by health care workers, making the health care setting safe from infection for patients and health care personnel. The Joint Commission on Accreditation of Healthcare Organizations requires the following 5 components of an infection control program for accreditation: (1) surveillance: monitoring patients and health care personnel for acquisition of infection and/or colonization; (2) investigation: identification and analysis of infection problems or undesirable trends; (3) prevention: implementation of measures to prevent transmission of infectious agents and to reduce risks for device- and procedure-related infections; (4) control: evaluation and management of outbreaks; and (5) reporting: provision of information to external agencies as required by state and federal laws and regulations (see http://www.jcaho.org). The infection control program staff has the ultimate authority to determine infection control policies for a health care organization with the approval of the organization's governing body. Long-term care facility (LTCF). A residential or outpatient facility designed to meet the biopsychosocial needs of persons with sustained self-care deficits. These include skilled nursing facilities, chronic disease hospitals, nursing homes, foster and group homes, institutions for the developmentally disabled, residential care facilities, assisted living facilities, retirement homes, adult day health care facilities, rehabilitation centers, and long-term psychiatric hospitals. Mask. A term that applies collectively to items used to cover the nose and mouth and includes both procedure masks and surgical masks (see http://www.fda.gov/cdrh/ode/guidance/094.html#4). Multidrug-resistant organism (MDRO). In general, a bacterium (excluding Mycobacterium tuberculosis) that is resistant to 1 or more classes of antimicrobial agents and usually is resistant to all but 1 or 2 commercially available antimicrobial agents (eg, methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, extended-spectrum beta-lactamase–producing or intrinsically resistant gram-negative bacilli). 176 Nosocomial infection. Derived from 2 Greek words, “nosos” (disease) and “komeion” (to take care of), refers to any infection that develops during or as a result of an admission to an acute care facility (hospital) and was not incubating at the time of admission. Personal protective equipment (PPE). A variety of barriers used alone or in combination to protect mucous membranes, skin, and clothing from contact with infectious agents. PPE includes gloves, masks, respirators, goggles, face shields, and gowns. Procedure mask. A covering for the nose and mouth that is intended for use in general patient care situations. These masks generally attach to the face with ear loops rather than ties or elastic. Unlike surgical masks, procedure masks are not regulated by the Food and Drug Administration. Protective environment. A specialized patient care area, usually in a hospital, with a positive air flow relative to the corridor (ie, air flows from the room to the outside adjacent space). The combination of high-efficiency particulate air filtration, high numbers (>12) of air changes per hour, and minimal leakage of air into the room creates an environment that can safely accommodate patients with a severely compromised immune system (eg, those who have received allogeneic hemopoietic stem cell transplantation) and decrease the risk of exposure to spores produced by environmental fungi. Other components include use of scrubbable surfaces instead of materials such as upholstery or carpeting, cleaning to prevent dust accumulation, and prohibition of fresh flowers or potted plants. Quasi-experimental study. A study undertaken to evaluate interventions but do not use randomization as part of the study design. These studies are also referred to as nonrandomized, pre-/postintervention study designs. These studies aim to demonstrate causality between an intervention and an outcome but cannot achieve the level of confidence concerning an attributable benefit obtained through a randomized controlled trial. In hospitals and public health settings, randomized control trials often cannot be implemented due to ethical, practical, and urgency reasons; therefore, quasi-experimental design studies are commonly used. However, even if an intervention appears to be effective statistically, the question can be raised as to the possibility of alternative explanations for the result. Such a study design is used when it is not logistically feasible or ethically possible to conduct a randomized controlled trial, (eg, during outbreaks). Within the classification of quasi-experimental study designs, there is a hierarchy of design features that may contribute to validity of results (Harris et al. CID 2004:38: 1586). Residential care setting. A facility in which people live, minimal medical care is delivered, and the psychosocial needs of the residents are provided for. Respirator. A personal protective device worn by health care personnel over the nose and mouth to protect them from acquiring airborne infectious diseases due to inhalation of infectious airborne particles 3 feet) when coughing. These measures are targeted to all patients with symptoms of respiratory infection and their accompanying family members or friends beginning at the point of initial encounter with a health care setting (eg, reception/triage in emergency departments, ambulatory clinics, health care provider offices). 126 (Srinivasin A ICHE 2004; 25: 1020; http://www.cdc.gov/flu/professionals/infectioncontrol/resphygiene.htm). Safety culture. Shared perceptions of workers and management regarding the level of safety in the work environment. A hospital safety climate includes the following organizational components: (1) senior management support for safety programs, (2) absence of workplace barriers to safe work practices, (3) cleanliness and orderliness of the worksite, (4) minimal conflict and good communication among staff members, (5) frequent safety-related feedback/training by supervisors, and (6) availability of PPE and engineering controls. 618 Source control. The process of containing an infectious agent either at the portal of exit from the body or within a confined space. The term is applied most frequently to containment of infectious agents transmitted by the respiratory route but could apply to other routes of transmission, (eg, a draining wound, vesicular or bullous skin lesions). Respiratory hygiene/cough etiquette that encourages individuals to “cover your cough” and/or wear a mask is a source control measure. The use of enclosing devices for local exhaust ventilation (eg, booths for sputum induction or administration of aerosolized medication) is another example of source control. Standard precautions. A group of infection prevention practices that apply to all patients, regardless of suspected or confirmed diagnosis or presumed infection status. Standard precautions represents a combination and expansion of universal precautions 778 and body substance isolation.1109 Standard precautions are based on the principle that all blood, body fluids, secretions, excretions except sweat, nonintact skin, and mucous membranes may contain transmissible infectious agents. Standard precautions include hand hygiene and, depending on the anticipated exposure, use of gloves, gown, mask, eye protection, or face shield. In addition, equipment or items in the patient environment likely to have been contaminated with infectious fluids must be handled in a manner to prevent transmission of infectious agents (eg, wear gloves for handling, contain heavily soiled equipment, properly clean and disinfect or sterilize reusable equipment before use on another patient). Surgical mask. A device worn over the mouth and nose by operating room personnel during surgical procedures to protect both surgical patients and operating room personnel from transfer of microorganisms and body fluids. Surgical masks also are used to protect health care personnel from contact with large infectious droplets (> 5 μm in size). According to draft guidance issued by the Food and Drug Administration on May 15, 2003, surgical masks are evaluated using standardized testing procedures for fluid resistance, bacterial filtration efficiency, differential pressure (air exchange), and flammability to mitigate the risks to health associated with the use of surgical masks. These specifications apply to any masks that are labeled surgical, laser, isolation, or dental or medical procedure (http://www.fda.gov/cdrh/ode/guidance/094.html#4). Surgical masks do not protect against inhalation of small particles or droplet nuclei and should not be confused with particulate respirators that are recommended for protection against selected airborne infectious agents (eg, Mycobacterium tuberculosis).
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            SARS among Critical Care Nurses, Toronto

            To determine factors that predispose or protect healthcare workers from severe acute respiratory syndrome (SARS), we conducted a retrospective cohort study among 43 nurses who worked in two Toronto critical care units with SARS patients. Eight of 32 nurses who entered a SARS patient’s room were infected. The probability of SARS infection was 6% per shift worked. Assisting during intubation, suctioning before intubation, and manipulating the oxygen mask were high-risk activities. Consistently wearing a mask (either surgical or particulate respirator type N95) while caring for a SARS patient was protective for the nurses, and consistent use of the N95 mask was more protective than not wearing a mask. Risk was reduced by consistent use of a surgical mask, but not significantly. Risk was lower with consistent use of a N95 mask than with consistent use of a surgical mask. We conclude that activities related to intubation increase SARS risk and use of a mask (particularly a N95 mask) is protective.
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              Is Open Access

              Cluster of SARS among Medical Students Exposed to Single Patient, Hong Kong

              We studied transmission patterns of severe acute respiratory syndrome (SARS) among medical students exposed exclusively to the first SARS patient in the Prince of Wales Hospital in Hong Kong, before his illness was recognized. We conducted a retrospective cohort study of 66 medical students who visited the index patient’s ward, including 16 students with SARS and 50 healthy students. The risk of contracting SARS was sevenfold greater among students who definitely visited the index case’s cubicle than in those who did not (10/27 [41%] versus 1/20 [5%], relative risk [RR] 7.4; 95% confidence interval [CI] 1.0 to 53.3). Illness rates increased directly with proximity of exposure to the index case. However, four of eight students who were in the same cubicle, but were not within 1 m of the index case-patient, contracted SARS. Proximity to the index case-patient was associated with transmission, which is consistent with droplet spread. Transmission through fomites or small aerosols cannot be ruled out.
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                Author and article information

                Contributors
                Role: Editor
                Journal
                PLoS One
                PLoS ONE
                plos
                plosone
                PLoS ONE
                Public Library of Science (San Francisco, USA )
                1932-6203
                2012
                26 April 2012
                : 7
                : 4
                Affiliations
                [1 ]Canadian Agency for Drugs and Technologies in Health (CADTH), Ottawa, Ontario, Canada
                [2 ]World Health Organization (WHO), Geneva, Switzerland
                [3 ]Departments of Medicine, Microbiology, Immunology and Infectious Diseases, Pathology & Laboratory Medicine, and the Calvin, Phoebe and Joan Synder Institute of Infection, Immunity and Inflammation, Faculty of Medicine, University of Calgary, Calgary, Canada
                University of Liverpool, United Kingdom
                Author notes

                Conceived and designed the experiments: KT KC MS CP-S JC. Performed the experiments: KT KC MS CP-S JC. Analyzed the data: KT KC MS CP-S JC. Contributed reagents/materials/analysis tools: KT KC MS CP-S JC. Wrote the paper: KT KC MS CP-S JC.

                Article
                PONE-D-12-00642
                10.1371/journal.pone.0035797
                3338532
                22563403
                Tran et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
                Page count
                Pages: 8
                Categories
                Research Article
                Medicine
                Clinical Research Design
                Case-Control Studies
                Cohort Studies
                Epidemiology
                Meta-Analyses
                Observational Studies
                Retrospective Studies
                Systematic Reviews
                Epidemiology
                Infectious Disease Epidemiology
                Infectious Diseases
                Viral Diseases
                SARS
                Infectious Disease Control

                Uncategorized

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