Prevalence of Ampicillin, Gentamicin and Vancomycin-Resistant Enterococci in Fecal Samples from Hospitalized and Non-Hospitalized Patients in Three Educational Hospitals of Tabriz University of Medical Sciences

Background and Objectives: Treatment of choice for enterococcal infections is usually synergistic combination of penicillin or a glycopeptide with an aminoglycoside (gentamicin or streptomycin). The efficacy of this combination is of debate due to emergence of multidrug resistant enterococcal strains. The main aim of this study was to determine the rate of intestinal colonization with antibiotic resistant enterococci among patients admitted to high risk wards and also out-patients. Materials and Methods: This study was performed by collecting stool or rectal swab specimens. Obtained isolates were confirmed as enterococci and characterized up to species level. Minimum inhibitory concentrations (MICs) of ampicillin, gentamicin and vancomycin were determined by agar dilution and/or E-test. Polymerase chain reaction (PCR) was performed to detect vanA/ vanB and E. faecalis/ E. faecium genes. Results: Among 291 tested enterococcal isolates, 240 (82.4%) isolates were resistant to gentamicin and 84 (28.8%) were resistant to ampicillin. Of these, 12 (14.2%) strains showed high level resistance to ampicillin (MICs, ≥ 256 ig/ml). Sixty three enterococcal isolates were resistant (MICs, ≥ 32 ig/ml) or intermediate (MICs, 8-16 ig/ml) to vancomycin. Of these, 15 strains showed high level resistance (MICs, ≥ 256 ig/ml) possessing vanA (n=12) and vanB (n=3) genes. Conclusion: Prevalence of intestinal colonization of antibiotic resistant enterococci, especially among high risk ward patients such as hematology/oncology and ICUs is of medical concern proposing improvement in antibiotic policies.