Epidemiology of Vancomycin-Resistant Enterococcus faecalis: a Case-Case-Control Study

Although much is known about vancomycin-resistant (VR)Enterococcus faecium , little is known about the epidemiology of VREnterococcus faecalis . The predilection of VRE. faecalis to transfer the vancomycin resistance determinant toStaphylococcus aureus is much greater than that of VRE. faecium . The epidemiology of VRE. faecalis has important implications regarding the emergence of vancomycin-resistantS. aureus (VRSA); 8 of 13 reported VRSA cases have been from Michigan. A retrospective case-case-control study was conducted at the Detroit Medical Center, located in southeastern Michigan. Unique patients with VRE. faecalis infection were matched to patients with strains of vancomycin-susceptible (VS)E. faecalis and to uninfected controls at a 1:1:1 ratio. Five hundred thirty-two VRE. faecalis cases were identified and were matched to 532 VSE. faecalis cases and 532 uninfected controls. The overall mean age of the study cohort (n = 1,596) was 63.0 ± 17.4 years, and 747 (46.8%) individuals were male. Independent predictors for the isolation of VRE. faecalis (but not VSE. faecalis ) compared to uninfected controls were an age of ≥65 years, nonhome residence, diabetes mellitus, peripheral vascular disease, exposure to cephalosporins and fluoroquinolones in the prior 3 months, and immunosuppressive status. Invasive procedures and/or surgery, chronic skin ulcers, and indwelling devices were risk factors for both VRE. faecalis and VSE. faecalis isolation. Cephalosporin and fluoroquinolone exposures were unique, independent predictors for isolation of VRE. faecalis . A majority of case patients had VRE. faecalis present at the time of admission. Control of VRE. faecalis , and ultimately VRSA, will likely require regional efforts focusing on infection prevention and antimicrobial stewardship.