Dissemination of antibiotic-resistant enterococci within the ward environment: the role of airborne bacteria and the risk posed by unrecognized carriers.
BACKGROUND
Colonized or infected patients pose a significant risk to noncolonized patients occupying the same room. The aim of this study was to investigate how far Enterococcus spp can spread from isolated and nonisolated patients.


METHODS
Conventional microbiological methods were used to recover enterococci from the air and from 62 high-contact sites located within the near-patient and wider ward environment. Samples were collected twice weekly for 17 weeks. The similarity between isolates was determined via pulsed-field gel electrophoresis.


RESULTS
Vancomycin-susceptible enterococci (VSE) were recovered from 352 of 2,046 environmental surfaces (17.2%) and from 27 of 66 air samples (40.9%). During study week 14, VSE was recovered from 75 of the 124 surfaces sampled, representing 21.3% of all VSE-positive sites. A gentamicin-resistant VS Enterococcus faecium clone was recovered in high numbers from the air (>100 cfu/m(3)) and from surfaces throughout a 4-bed bay. The same clone was recovered from an adjacent isolation room as well. A total of 55 surfaces were contaminated with vancomycin-resistant enterococci (VRE). The environment of 2 isolated patients accounted for 85% of contaminated sites. Neither patient was known to be VRE-positive.


CONCLUSIONS
Unrecognized colonization and/or the aerosolization of enterococci together with inadequate cleaning can lead to heavy, widespread, and persistent environmental contamination. All pose a significant risk for acquisition of antibiotic-resistant enterococci.
Department of Microbiology, University College London Hospitals, National Health Service Foundation Trust, London, UK. monika.muzslay@uclh.nhs.uk
Monika
M
Muzslay
Ginny
G
Moore
Jane F
JF
Turton
A Peter
AP
Wilson
D000391:Air Microbiology; D002353:Carrier State / Q000382:microbiology*; D003428:Cross Infection / Q000453:epidemiology* / Q000635:transmission; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D016983:Enterococcus / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification*; D005260:Female; D016908:Gram-Positive Bacterial Infections / Q000453:epidemiology* / Q000635:transmission; D006801:Humans; D008297:Male; D058889:Molecular Typing; D011446:Prospective Studies; D018570:Risk Assessment