The phenotypic and genotypic characterization of vancomycin-resistant enterococci in outpatients’ urine culture

Abstract

Introduction/Objective. In the era of emerging antibacterial resistance, the major burden of resistant strains is on hospitalized patients. Although community factors are also important in the spread of resistance, less attention has been paid to non-healthcare settings. The aim of the study is to determine the prevalence of vancomycin-resistant enterococci (VRE) in the outpatient?s urine culture and to perform phenotypic and genotypic characterization of VRE strains. Methods. During an 18-month period, a total of 5,164 Enterococcus spp. strains were isolated from urine and identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Antimicrobial susceptibility testing was performed by disk diffusion method and by gradient test for glycopeptideresistant strains. Genotypic characterization of VRE strains was done by multiplex polymerase chain reaction for the detection of the vancomycin resistance genes. Results. Among the isolated enterococci, 5,060 (98%) were E. faecalis and 104 (2%) were E. faecium. E. faecalis strains were susceptible to all tested antibiotics except norfloxacin (33% of strains were resistant), while E. faecium showed high level of resistance to most of the tested agents (91.3% to ampicillin, 77% to norfloxacin, and 75% to nitrofurantoin), and 26% of strains were resistant to vancomycin and teicoplanin. VanA gene was detected in all vancomycin resistant E. faecium (VREfm) strains. Conclusion. A high proportion of VREfm was noticed among outpatients in our country. All analyzed VREfm strains belonged to vanA genotype. Future surveillance studies of VRE are needed to follow up on this baseline study to monitor any possible changes in abundance and genotype of VRE in this population group.