Antibiotic resistant fecal isolates of Enterococci among unselected patients outside the clinical sector: an epidemiological study from Southern Germany

PURPOSE: The aim of the study was to assess the prevalence and determinants of antibiotic-resistant Enterococci in a large group of outpatients in Southern Germany. METHODS: Stool samples were collected from 497 unselected patients aged 40-75 years attending general practitioners. Enterococcus faecium (E. faecium) and Enterococcus faecalis (E. faecalis) were cultured and minimal inhibitory concentrations of antibiotics used inside and outside the clinical sector were tested. RESULTS: E. faecium and E. faecalis could be identified and cultured in 60 (12.4%) and 205 (41.2%) of the stool samples, respectively. Under non-selective culture conditions no vancomycin-resistant Enterococcus (VRE) isolate was found. Only E. faecium isolates showed resistance to fluoroquinolones, 40% were resistant to ciprofloxacin. The prevalences of E. faecium resistance to ampicillin and doxycycline were 3.3% and 13.3%, respectively, whereas 0.5% and 29.6% of the E. faecalis isolates were resistant to ampicillin and doxycycline, respectively. Antibiotic use during the last 3 months was significantly associated with antibiotic resistance (to either ampicillin, imipenem, or doxycycline) of E. faecalis isolates (OR: 2.9; CI: 1.2-6.8). CONCLUSIONS: Prevalences of resistance were generally lower than and patterns of resistance were quite different from previous investigations in the clinical setting. Recent antibiotic use was associated with increased colonization with resistant strains.