A Dynamic Transmission Model to Evaluate the Effectiveness of Infection Control Strategies

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Abstract

Background.

The advancement of knowledge about control of antibiotic resistance depends on the rigorous evaluation of alternative intervention strategies. The STAR*ICU trial examined the effects of active surveillance and expanded barrier precautions on acquisition of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) in intensive care units. We report a reanalyses of the STAR*ICU trial using a Bayesian transmission modeling framework.

Methods.

The data included admission and discharge times and surveillance test times and results. Markov chain Monte Carlo stochastic integration was used to estimate the transmission rate, importation, false negativity, and clearance separately for MRSA and VRE. The primary outcome was the intervention effect, which when less than (or greater than) zero, indicated a decreased (or increased) transmission rate attributable to the intervention.

Results.

The transmission rate increased in both arms from pre- to postintervention (by 20% and 26% for MRSA and VRE). The estimated intervention effect was 0.00 (95% confidence interval [CI], −0.57 to 0.56) for MRSA and 0.05 (95% CI, −0.39 to 0.48) for VRE. Compared with MRSA, VRE had a higher transmission rate (preintervention, 0.0069 vs 0.0039; postintervention, 0.0087 vs 0.0046), higher importation probability (0.22 vs 0.17), and a lower clearance rate per colonized patient-day (0.016 vs 0.035).

Conclusions.

Transmission rates in the 2 treatment arms were statistically indistinguishable from the pre- to postintervention phase, consistent with the original analysis of the STAR*ICU trial. Our statistical framework was able to disentangle transmission from importation and account for imperfect testing. Epidemiological differences between VRE and MRSA were revealed.

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Most cited references 36

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Targeted versus universal decolonization to prevent ICU infection.

Susan Huang, Edward Joel Septimus, Ken Kleinman … (2013)

Both targeted decolonization and universal decolonization of patients in intensive care units (ICUs) are candidate strategies to prevent health care-associated infections, particularly those caused by methicillin-resistant Staphylococcus aureus (MRSA). We conducted a pragmatic, cluster-randomized trial. Hospitals were randomly assigned to one of three strategies, with all adult ICUs in a given hospital assigned to the same strategy. Group 1 implemented MRSA screening and isolation; group 2, targeted decolonization (i.e., screening, isolation, and decolonization of MRSA carriers); and group 3, universal decolonization (i.e., no screening, and decolonization of all patients). Proportional-hazards models were used to assess differences in infection reductions across the study groups, with clustering according to hospital. A total of 43 hospitals (including 74 ICUs and 74,256 patients during the intervention period) underwent randomization. In the intervention period versus the baseline period, modeled hazard ratios for MRSA clinical isolates were 0.92 for screening and isolation (crude rate, 3.2 vs. 3.4 isolates per 1000 days), 0.75 for targeted decolonization (3.2 vs. 4.3 isolates per 1000 days), and 0.63 for universal decolonization (2.1 vs. 3.4 isolates per 1000 days) (P=0.01 for test of all groups being equal). In the intervention versus baseline periods, hazard ratios for bloodstream infection with any pathogen in the three groups were 0.99 (crude rate, 4.1 vs. 4.2 infections per 1000 days), 0.78 (3.7 vs. 4.8 infections per 1000 days), and 0.56 (3.6 vs. 6.1 infections per 1000 days), respectively (P<0.001 for test of all groups being equal). Universal decolonization resulted in a significantly greater reduction in the rate of all bloodstream infections than either targeted decolonization or screening and isolation. One bloodstream infection was prevented per 54 patients who underwent decolonization. The reductions in rates of MRSA bloodstream infection were similar to those of all bloodstream infections, but the difference was not significant. Adverse events, which occurred in 7 patients, were mild and related to chlorhexidine. In routine ICU practice, universal decolonization was more effective than targeted decolonization or screening and isolation in reducing rates of MRSA clinical isolates and bloodstream infection from any pathogen. (Funded by the Agency for Healthcare Research and the Centers for Disease Control and Prevention; REDUCE MRSA ClinicalTrials.gov number, NCT00980980).

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Veterans Affairs initiative to prevent methicillin-resistant Staphylococcus aureus infections.

Krystin Ambrose, Rajiv Jain, R Freyberg … (2011)

Health care-associated infections with methicillin-resistant Staphylococcus aureus (MRSA) have been an increasing concern in Veterans Affairs (VA) hospitals. A "MRSA bundle" was implemented in 2007 in acute care VA hospitals nationwide in an effort to decrease health care-associated infections with MRSA. The bundle consisted of universal nasal surveillance for MRSA, contact precautions for patients colonized or infected with MRSA, hand hygiene, and a change in the institutional culture whereby infection control would become the responsibility of everyone who had contact with patients. Each month, personnel at each facility entered into a central database aggregate data on adherence to surveillance practice, the prevalence of MRSA colonization or infection, and health care-associated transmissions of and infections with MRSA. We assessed the effect of the MRSA bundle on health care-associated MRSA infections. From October 2007, when the bundle was fully implemented, through June 2010, there were 1,934,598 admissions to or transfers or discharges from intensive care units (ICUs) and non-ICUs (ICUs, 365,139; non-ICUs, 1,569,459) and 8,318,675 patient-days (ICUs, 1,312,840; and non-ICUs, 7,005,835). During this period, the percentage of patients who were screened at admission increased from 82% to 96%, and the percentage who were screened at transfer or discharge increased from 72% to 93%. The mean (±SD) prevalence of MRSA colonization or infection at the time of hospital admission was 13.6±3.7%. The rates of health care-associated MRSA infections in ICUs had not changed in the 2 years before October 2007 (P=0.50 for trend) but declined with implementation of the bundle, from 1.64 infections per 1000 patient-days in October 2007 to 0.62 per 1000 patient-days in June 2010, a decrease of 62% (P<0.001 for trend). During this same period, the rates of health care-associated MRSA infections in non-ICUs fell from 0.47 per 1000 patient-days to 0.26 per 1000 patient-days, a decrease of 45% (P<0.001 for trend). A program of universal surveillance, contact precautions, hand hygiene, and institutional culture change was associated with a decrease in health care-associated transmissions of and infections with MRSA in a large health care system.

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Importance of the environment in meticillin-resistant Staphylococcus aureus acquisition: the case for hospital cleaning.

Stephanie Dancer (2008)

In the UK, we continue to debate the importance of hospital cleaning in relation to increasing numbers of patients acquiring meticillin-resistant Staphylococcus aureus (MRSA). However, there is little direct evidence for the effectiveness of cleaning because it has never been afforded scientific status. Hospital hygiene is usually assessed visually, but this does not necessarily correlate with microbiological risk. A more robust case for hospital cleaning can be presented by considering the evidence for all the stages of the staphylococcal transmission cycle between human beings and their environment. Cleaning has already been accepted as an important factor in the control of other hardy environmental pathogens, such as Clostridium difficile, vancomycin-resistant enterococci, norovirus, and Acinetobacter spp. This Review will show why the removal of dirt might have more impact on the control of MRSA than previously thought. Introduction of additional cleaning services is easier than improvements in hand-hygiene compliance.

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Author and article information

Journal

Journal ID (nlm-ta): Open Forum Infect Dis

Journal ID (iso-abbrev): Open Forum Infect Dis

Journal ID (publisher-id): ofid

Title: Open Forum Infectious Diseases

Publisher: Oxford University Press (US )

ISSN (Electronic): 2328-8957

Publication date Collection: Winter 2017

Publication date (Electronic): 10 February 2017

Publication date PMC-release: 10 February 2017

Volume: 4

Issue: 1

Electronic Location Identifier: ofw247

Affiliations

[1 ]Informatics, Decision Enhancement, and Analytical Sciences 2.0 Center, VA Salt Lake City Health Care System , City, Utah

[2 ]Divisions of Epidemiology

[3 ]Genetic Epidemiology, University of Utah School of Medicine , Salt Lake City

[4 ]Division of Pediatric Infectious Diseases, Mayo Clinic , Rochester, Minnesota

Author notes

Presented in part: ID Week 2014, Philadelphia, PA.

Correspondence: K. Khader, PhD, Research Assistant Professor, IDEAS 2.0 Center, VA Salt Lake City Health Care System, Division of Epidemiology, University of Utah School of Medicine, 295 Chipeta Way, Salt Lake City, UT 84132 ( karim.khader@ 123456hsc.utah.edu ).

Article

Publisher ID: ofw247

DOI: 10.1093/ofid/ofw247

PMC ID: 5499871

PubMed ID: 28702465

SO-VID: 2e9d730c-33f6-4f40-909c-92748ab829c5

License:

This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

History

Date received : 18 July 2016

Date accepted : 11 November 2016

Page count

Pages: 8

Funding

Funded by: Centers for Disease Control and Prevention’s Epicenter Program

Award ID: 07FED706506

Funded by: University of Utah Study Design & Biostatistics Center

Funded by: National Center for Research Resources http://dx.doi.org/10.13039/100000097

Funded by: National Center for Advancing Translational Sciences, National Institutes of Health,

A Dynamic Transmission Model to Evaluate the Effectiveness of Infection Control Strategies

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Abstract

Background.

Methods.

Results.

Conclusions.

Related collections

Decoding Infection and Transmission

Most cited references 36

Targeted versus universal decolonization to prevent ICU infection.

Veterans Affairs initiative to prevent methicillin-resistant Staphylococcus aureus infections.

Importance of the environment in meticillin-resistant Staphylococcus aureus acquisition: the case for hospital cleaning.

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