Vancomycin resistance, esp, and strain relatedness: a 1-year study of enterococcal bacteremia.

The prevalence of esp, a gene associated with infection-derived and outbreak strains, in enterococcal blood isolates from 2002 was determined. Fifty-five of 137 (40.1%) Enterococcus faecalis isolates, 30 of 58 (51.7%) E. faecium isolates, 1 of 1 E. raffinosus isolate, 0 of 4 E. gallinarum isolates, and 0 of 1 E. casseliflavus isolate were positive. esp wasn't associated with vancomycin resistance (VR) or clinical service. VR E. faecium isolates were less genetically diverse than vancomycin-susceptible strains. A large cluster of VR isolates, belonging to esp-positive E. faecium, was revealed. These data support the hypothesis that esp and VR may contribute to dissemination of particular clones.