External sources of vancomycin-resistant enterococci for intensive care units

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.

Prospective, descriptive analysis.

An MICU of a public hospital.

Three hundred and one consecutively admitted patients.

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.

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.