Clonal diversity of vancomycin-resistant enterococci from an outbreak in atertiary care university hospital

Background: Enterococci have become important nosocomial pathogens and now account for approximately 12% of nosocomial infections. Enterococci can be transferred from patient to patient and from health care personnel to patie nt. We investigated the clonal diversity of vancomycin-resistant enterococc i (VRE) causing an outbreak of infections and attempted to determine the pa tterns of spread of these bacteria in a university hospital. Methods: Ribotyping was used to examine the clonal diversity of 50 VRE isol ates, including 23 from wounds, 14 from urine, 8 from blood, 3 from the rec tum, 1 from drainage, and 1 from the cornea. Results: Nine patients were infected with Enterococcus faecalis, 10 with En terococcus faecium, 3 with both E faecalis and E faecium, and 1 with Entero coccus avium. The results suggest that the sources of the VRE infections in cluded endogenous strains and strains acquired by transmission from attendi ng staff or from the environment. Three patients were infected by both noso comial and endogenous strains. Conclusions: These data suggest that the collection and analysis of several isolates from repeated specimens is necessary to obtain a fuller understan ding of the epidemiology and population structure of antibiotic-resistant e nterococci.