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 epidemiologyof 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 identifiedin 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, thepresence of invasive devices, surgery, and admission to an intensive-careunit were not significantly associated with HLGRbacteremia. Mortality during hospitalization was65%, with no difference between figures for HLGR and non-HLGR infections. This high mortality regardless of gentamicinsusceptibility status suggests that E. faecalis bacteremia is a marker for severe illness. In contrast to previousstudies, this investigation identified no clinical factors associated with HLGR E.faecalis bacteremia.