Clinical and molecular epidemiology of Enterococcus faecalis bacteremia, with special reference to strains with high-level resistance to gentamicin.

The objective of this study was to characterize the clinical and molecular epidemiology of Enterococcus faecalis bacteremia, specifically that involving strains with high-level resistance to gentamicin (HLGR). Episodes of E. faecalis bacteremia at the Buffalo Veterans Affairs Medical Center from January 1986 to September 1989 were retrospectively identified. Of 94 episodes, 45 (48%) were due to strains with HLGR. Hemolytic activity was detected with greater frequency (85%) among the latter strains than among those without HLGR (P < .001). Of the 54 episodes for which medical charts were available for review, 94% were hospital acquired, and 46% were due to strains with HLGR. An examination of the plasmid DNA content of isolates revealed restriction-fragment-length polymorphism. One plasmid pattern was identified in 15 isolates with HLGR (P < .001), and chromosomal DNA digest patterns suggested a common clonality; there was no direct evidence for patient-to-patient spread of these strains. The use of antibiotics, the presence of invasive devices, surgery, and admission to an intensive-care unit were not significantly associated with HLGR bacteremia. Mortality during hospitalization was 65%, with no difference between figures for HLGR and non-HLGR infections. This high mortality regardless of gentamicin susceptibility status suggests that E. faecalis bacteremia is a marker for severe illness. In contrast to previous studies, this investigation identified no clinical factors associated with HLGR E. faecalis bacteremia.