External sources of vancomycin-resistant enterococci for intensive care units.

OBJECTIVE: The incidence of colonization and infection with vancomycin-resistant enterococci (VRE) has increased dramatically in the last 5 yrs, especially in intensive care units (ICUs). We studied VRE-colonization in patients on admission to a medical ICU (MICU) where VRE colonization is endemic.

DESIGN: Prospective, descriptive analysis.

SETTING: An MICU of a public hospital.

PATIENTS: Three hundred and one consecutively admitted patients.

MEASUREMENTS AND MAIN RESULTS: Rectal swabs were obtained on admission from all patients. VRE isolates from all colonized patients were genetically fingerprinted by pulsed-field gel-electrophoresis (PFGE). Forty-three (14%) of 301 patients were colonized with VRE on MICU admission. Three (7%) of these 43 patients were admitted directly from the community without prior hospital contact. Risk of colonization on admission was related to the length of stay in the hospital before MICU-admission (odds ratio 4.65 for patients with a stay of at least 3 days) and previous in-hospital use of antibiotics. Of 22 VRE PFGE strain types recognized in the MICU during the study period, four (18%) were introduced by patients admitted directly from the community and ten (45%) were introduced by patients admitted from other hospital wards.

CONCLUSIONS: These results show that although ICUs are considered epicenters for antibiotic resistance, sources extraneous to our MICU (e.g., other wards) contributed the majority of VRE strain types in the unit.