Antibiotic Susceptibility Pattern and Virulence Genes in Enterococcus spp. Isolated From Clinical Samples of Milad Hospital of Tehran, Iran

Background: Enterococcus spp. are part of the normal flora of humans and animals. The nosocomial pathogenicity of Enterococcus spp. has emerged in recent years and has caused great concern due to developing of resistance to many antimicrobial agents. Objectives: The current study aimed to determine the resistance pattern and the type of virulence genes in Enterococcus spp. isolated from Milad hospital of Tehran, Iran. Materials and Methods: The current observational study was conducted from Apr 2014 to Feb 2015 on a total of 149 Enterococcus species isolated from Milad hospital in Tehran, Iran. The antibiotic susceptibility pattern of the bacteria was determined by the disc diffusion method for eight antibiotics. Minimum inhibitory concentration (MIC) of vancomycin was also done using agar-dilution assay by clinical and laboratory standards institute (CLSI) recommendations. The sodA, esp, cyl, ace and gelE genes were detected by polymerase chain reaction (PCR) assay. Results: About 37.5%, 73%, 86.6%, 35.8%, 69%, 60.8%, 45% and 79% of the isolates were resistant to vancomycin, tetracycline, gentamicin, chloramphenicol, ciprofloxacin, penicillin, ampicillin and erythromycin, respectively. MIC on 38% of the isolates was 256 g/mL. Although, the prevalence of vancomycin-resistant Enterococcus (VRE) strains belonged to two species, E. faecium showed high resistance to a broad range of antibiotics. In total, 94 isolates were positive for esp, and 59, 48 and 3 isolates were positive for ace, cylA and gelE, Respectively. Conclusions: The results of the current study designate the important role of medical samples as reservoirs of resistance inducing elements. Early detection of VRE with their virulence trait will help to prevent the spread of vancomycin resistant Enterococcus species. Supervision for antibiotic usage in hospitals, especially for last option antibiotics, can prevent the spread of resistant isolates and losing all treatment options in the future.