Role of environmental contamination as a risk factor for acquisition of vancomycin-resistant enterococci in patients treated in a medical intensive care unit

Background: Colonization pressure, proximity to another case, exposure to a nurse who cares for another case, enteral feeding, and the use of sucralfate, vancomycin hydrochloride, cephalosporins, or antibiotics are among the defined risk factors for acquisition of vancomycin-resistant enterococci (VRE) in the intensive care unit (ICU) setting. However, the role of rooms with contaminated environmental surfaces has not been well delineated. Methods: Retrospective case-control study conducted on patients admitted to the medical ICU (MICU) of a tertiary-care, university-affiliated medical center during a 9-month period. Patients who acquired VRE (cases) were matched with 2 randomly selected control subjects who did not acquire VRE and had been in the MICU for at least the same number of days. Results: Thirty cases were matched with 60 appropriate controls. Cases were more likely to have been in the hospital for longer than 7 days before MICU admission (P=.009); to have occupied a specific room with persisting contaminated surfaces (P=.06); to have had a central venous catheter (P=.05); to have received vancomycin (P=.02), cephalosporins (P=.03), and quinolones (P =.006) before MICU admission; and to have received vancomycin (P=.02) and metronidazole sodium phosphate (P=.03) after MICU admission. Multivariate analysis showed that a hospital stay of longer than 1 week before MICU admission (P=.04), use of vancomycin before or after MICU admission (P=.03), use of quinolones before MICU admission (P=.03), and placement in a contaminated room (P=.02) were the best predictors of VRE acquisition. Conclusions: Among all other factors associated with VRE transmission, VRE acquisition may depend on room contamination, even after extensive cleaning. This study underscores the need for better cleaning and the role of the environment in transmission of VRE.