Emergence of OptrA Gene Mediated Linezolid Resistance among Enterococcus Faecium: A Pilot Study from a Tertiary Care Hospital, India.

is the third most common cause of nosocomial infections. Linezolid (LNZ) is a reserve antibiotic recommended for infections caused by vancomycin resistant (VREfm).  The aim of the present study was to investigate the prevalence of  gene among linezolid resistant (LREfm) and to study the molecular epidemiology using pulse field gel electrophoresis (PFGE). Clinically significant LREfm were identified and antimicrobial susceptibility was performed by disc diffusion. Minimum inhibitory concentration (MIC) of linezolid, vancomycin, daptomycin and quinupristin/dalfopristin was determined by E-test. PCR and PCR-RFPL were performed for the detection of  gene and G2576T mutation respectively. Molecular epidemiology was studied by PFGE. A total of 1081 clinically significant species were isolated which included 63.5% (n=687) and 36.5% (n=394). LREfm (30/687) were further studied. Multidrug resistance and ancomycin resistance was 100% and 80%, respectively. Linezolid MIC range was 8-256µg/ml and the most common mechanism of resistance was gene (83.3%) followed by G2576T mutation (33.3%). PFGE analysis demonstrated 4 major clones. The  gene mediated linezolid resistance was high and PFGE suggests resistance was emerging in the different background strains irrespective of resistance mechanism. Studies are required to investigate factors driving the emergence of linezolid resistance. The review suggests that this is the first report of mediated resistance in from India.