Clinical isolates of Vibrio fluvialis from Kolkata, India, obtained during 2006: plasmids, qnr and mutation in gyrase A as mechanisms of multidrug resistance

Abstract

The resistance profile and its correlation with genetic factors was investigated in twelve isolates of Vibrio fluvialis obtained from the hospitalised patients in Kolkata, India, in year 2006. All the strains displayed drug resistance with varying antibiograms. However, resistance to ampicillin and neomycin was common to all of them. Three isolates harboured plasmids carrying drug resistance genes that could be transferred to recipient strains by conjugation and transformation. Polymerase chain reactions indicated absence of class 1 integrons and SXT elements in these isolates. Mutation in gyrase A (Serine 83-Isoleucine) and qnrB1 gene were found to contribute towards quinolone resistance. Out of twelve, qnrB1 gene was associated only with two plasmid-bearing isolates L10734 and L9978 that displayed resistance to quinolones. The gene was transferable during transformation and conjugation indicating that it was plasmid-borne . These data considered together indicated that plasmids, qnrB1 and mutation in gyrase A were responsible for the observed drug resistance in these strains. To the best of our knowledge, this is the first report of presence of qnrB1 allele from V. fluvialis isolates from India.