An Investigation of the vanA and vanB Genes in Enterococcus faecalis and Enterococcus faecium Strains Isolated from the Hospitalized Patients in Shariati Hospital and Evaluation of Their Antibiotic Susceptibility

One of the public concerns is emergence of Vancomycin-resistant Enterococci. VanA and vanB genes is responsible for resistance to high concentrations of Vancomycin. The purpose of this study is detection of the vanA and vanB genes in the Enterococcus faecalis and Enterococcus faecium isolated from hospitalized patients in Shariati hospital and their antibiotic susceptibility profile. A total of 228 samples, including urine, blood, wound and stool were collected from patients referred to the Shariati hospital. Suspected grown colonies were identified by standard methods and then antibiotic susceptibility testing by disk diffusion assay performed according to Clinical and Laboratory Standards Institute (CLSI). E. test was used to determination of MIC levels on the samples with resistance to Vancomycin. Distribution of vanA and vanB genes was determined by using of PCR method. In this study, out of 113 achieved Enterococcus, the highest and lowest prevalence of E. faecalis and E. faecium were 103 (91.1%) and 10 (8.9%), respectively. In the disk diffusion method, 11 (7/9%) strains were resistant to Vancomycin. All Vancomycin resistance isolates revealed vanA, but not vanB. The increase of Vancomycin resistance strains is a serious threat in the world and our country. Furthermore, the limited treatment options for patients with Enterococcus infections caused increasing cost and transfer resistance genes to other bacteria.