Genotypic Characterization of Vancomycin-Resistant Enterococcus spp. In Tertiary Center, Iran

Background: Enterococci infection rate, mortality and morbidity have been increased in recent decades accompanied by progressive emerging antimicrobial resistance. Vancomycin-resistant enterococci (VRE), important pathogen in hospitalized patients, has distinct antibiotic susceptibility to glycopeptides that varied genetically and can influence in choosing therapeutic agents. In this study, we aimed to determine the patterns of antimicrobial resistance according to the genotypic variations in VREs. Methods: Enterococci samples were isolated from different clinical specimens followed by antimicrobial susceptibility that was determined by the disk diffusion method during one year 2015-2016. Subsequently, VREs were selected and extraction of total DNA was performed using the QIAmp DNA mini kit. The eight oligonucleotide primer pairs were used to amplify the genes vanA, vanB, vanC1, vanC2, vanC2/3, esp, and hyl. Multiplex polymerase chain reaction (PCR) was performed to identify Van A, Van B, Van C, Van D and clonal complex 17 (CC17). Results: A total of 235 enterococci were isolated, including 121 and 114 Enterococcus faecalis and Enterococcus faecium, respectively. Most of VREs (42% of all enterococci) were E. faecium (91.1% vs. 8.9% E. faecalis). All VREs had Van A; and Van B, Van C and Van D genes were not found in any isolates. The frequency rate of CC17, genetic subset of E. faecium, was 68.3%. Conclusion: In conclusion, we can assume that the most frequent genotype of VRE in our country is VAN A and literally, the other genotypes