Detection of vanA and vanB Genetic Determinants in Vancomycin Resistant Enterococci in Kashmir Region of North India-A Hospital Based Study

Abstract

Introduction: Enterococci have emerged as one of the most important multidrug resistant microorganisms over the past few decades and have been reported to be the third most important hospital-acquired pathogens. Indiscriminate use of vancomycin and extended spectrum cephalosporins in hospitals has significantly contributed to the emergence of vancomycin resistance in Enterococci. Transferable vancomycin resistance in Enterococci is predominantly encoded for by vanA and vanB gene clusters. Polymerase Chain Reaction (PCR) allows rapid detection of these genes which is very important for infection control and prevention of nosocomial spread. Aims: To estimate prevalence of VRE infections in our hospital and identify genetic determinants of vancomycin resistance in these isolates. Methodology: This prospective study was carried out in the department of Microbiology, Sher-i-Kashmir Institute of Medical Sciences, Srinagar J&K over a period of one year from 1st August 2013 to 30th July 2014. VRE isolated from clinical samples taken from patients admitted in the hospital or attending OPD were subject to DNA extraction and genotyping by PCR using vanA and vanB specific primers. PCR amplicons were then analyzed on 2% agarose gel by electrophoresis using ethidium bromide stain. Results: Out of total 498 isolated Enterococcus spp., 35 (7.0%) were found to be vancomycin resistant after MIC testing. All the VRE were isolated from inpatients particularly from ICU (34.3%; p<0.001). Majority of VRE were isolated from blood samples (34.3%; p<0.001). Prior use of vancomycin was noted in 54.3% patients from whom VRE were isolated (p=0.003). All the 35 VRE isolates were positive for presence of vanA gene, whereas none of the VRE in our study harbored vanB gene which was in accordance with phenotypic resistance pattern of the isolates. Conclusion: VRE have emerged as important pathogens in our hospital with a prevalence of 7.0% and vanA is the predominant genotype of the resistant strains.