Phage Lysins for Fighting Bacterial Respiratory Infections: A New Generation of Antimicrobials

Bacteriophage lytic enzymes quickly destroy the cell wall of the host bacterium to release progeny phage. Because such lytic enzymes specifically kill the species in which they were produced, they may represent an effective way to control pathogenic bacteria without disturbing normal microflora. In this report, we studied a murein hydrolase from the streptococcal bacteriophage C(1) termed lysin. This enzyme is specific for groups A, C, and E streptococci, with little or no activity toward several oral streptococci or other commensal organisms tested. Using purified lysin in vitro, we show that 1,000 units (10 ng) of enzyme is sufficient to sterilize a culture of approximately 10(7) group A streptococci within 5 seconds. When a single dose of lysin (250 units) is first added to the oral cavity of mice, followed by 10(7) live group A streptococci, it provides protection from colonization (28.5% infected, n = 21) compared with controls without lysin (70.5% infected, n = 17) (P < 0.03). Furthermore, when lysin (500 units) was given orally to 9 heavily colonized mice, no detectable streptococci were observed 2 h after lysin treatment. In all, these studies show that lysin represents a unique murein hydrolase that has a rapid lethal effect both in vitro and in vivo on group A streptococci, without affecting other indigenous microorganisms analyzed. This general approach may be used to either eliminate or reduce streptococci from the upper respiratory mucosal epithelium of either carriers or infected individuals, thus reducing associated disease.

Antimicrobial resistance poses a growing threat to public health and the provision of health care. Its surveillance should provide up-to-date and relevant information to monitor the appropriateness of therapy guidelines, antibiotic formulary, antibiotic stewardship programmes, public health interventions, infection control policies, and antimicrobial development. In Europe, although the European Antimicrobial Resistance Surveillance Network provides annual reports on monitored resistant bacteria, national surveillance efforts are still fragmented and heterogeneous, and have substantial structural problems and issues with laboratory data. Most incidence and prevalence data cannot be linked with relevant epidemiological, clinical, or outcome data. Genetic typing, to establish whether trends of antimicrobial resistance are caused by spread of resistant strains or by transfer of resistance determinants among different strains and species, is not routinely done. Furthermore, laboratory-based surveillance using only clinical samples is not likely to be useful as an early warning system for emerging pathogens and resistance mechanisms. Insufficient coordination of surveillance systems of human antimicrobial resistance with animal surveillance systems is even more concerning. Because results from food surveillance are considered commercially sensitive, they are rarely released publicly by regulators. Inaccurate or incomplete surveillance data delay a translational approach to the threat of antimicrobial resistance and inhibit the identification of relevant target microorganisms and populations for research and the revitalisation of dormant drug-discovery programmes. High-quality, comprehensive, and real-time surveillance data are essential to reduce the burden of antimicrobial resistance. Improvement of national antimicrobial resistance surveillance systems and better alignment between human and veterinary surveillance systems in Europe must become a scientific and political priority, coordinated with international stakeholders within a global approach to reduce the burden of antimicrobial resistance.

We report on intensive care nosocomial pneumonia (NP) in Europe through a review of EU-VAP/CAP manuscripts: a prospective observational study, enrolling patients from 27 ICUs in nine European countries. From 2,436 eligible ICU patients, 827 cases presented NP, with 18.3 episodes of VAP per 1000 ventilator-days. Most common findings were worsening oxygenation, purulent respiratory secretions and temperature increase. At least three criteria from Clinical Pulmonary Infection score (CPIS) were present in 77.9 % of episodes, but only 0.2 % met six CPIS criteria. Diagnosis was confirmed mainly noninvasively (74.8 %), with half qualitative and quantitative cultures. The dominant isolate was S. aureus in Spain, France, Belgium and Ireland, P. aeruginosa in Italy and Portugal, Acinetobacter in Greece and Turkey, but Escherichia coli in Germany. NP resulted in 6 % higher mortality, longer ICU stay and duration of mechanical ventilation (12 and 10 days). COPD and age ≥45 years were not associated with higher VAP incidence but did correlate with increased mortality. Trauma had higher VAP incidence but lower mortality. Bacteremia (led by MRSA and Acinetobacter baumannii) was documented in 14.6 %, being associated with extra ICU stay and mortality. Vasopressors and ICUs with above 25 % prevalence of Potential Resistant Organisms (PRM) were independently associated with PRM, being documented in 50.7 % of patients with early-onset VAP without known risk factors. Most patients initially received combination therapy. Delay in appropriate antimicrobial choice significantly increased mortality, and LOS in survivors was six days longer (p < 0.05). In conclusion, NP management in Europe presents local differences and major shifts when compared to reports from North America, outcomes of randomized trials and general guidelines.