Analysis of beta-lactamases, bla NDM-1 phylogeny & plasmid replicons in multidrug-resistant Klebsiella spp. from a tertiary care centre in south India.

BACKGROUND & OBJECTIVES: β-lactamases play a predominant role in drug-resistance amongst Enterobacteriaceae. Presence of genes on transferable plasmids encoding these enzymes favours their dissemination across species and genera within and outside geographical boundaries. This study was aimed to understand the presence of β-lactamases and transferable plasmids in clinical isolates of Klebsiella spp. which can contribute to the spread of resistance determinants.

METHODS: A total of 41 clinical isolates of Klebsiella spp., collected from a tertiary care centre in Kerala, India, were checked for antibiotic sensitivity and the presence of plasmids. The ability to produce extended-spectrum β-lactamases (ESBLs) and metallo-β-lactamases (MBLs) was screened for and confirmed in 29 plasmid-harbouring isolates. blaNDM-1-specific primers were used for polymerase chain reaction amplification with plasmid DNA as template to determine episomal prevalence of this gene and its sequence-based phylogeny employing similar sequences from GenBank. Plasmid replicon typing was also carried out to determine the presence of transferable plasmids.

RESULTS: Our results showed a high degree of multidrug-resistant (MDR) pathogens with ESBL production confirmed in 52 per cent, MBL in 31 per cent and co-production of both enzymes in seven per cent of the plasmid-bearing isolates. Plasmid DNA from 14 per cent of the isolates produced blaNDM-1-specific amplicons which showed sequence homology with those from bacteria of different genera and geographical areas. The predominant replicon type was found to be that of conjugative plasmids belonging to the incompatibility group - IncFIIK.

INTERPRETATION & CONCLUSIONS: This study provides insight into the predominance of various β-lactamases and potent gene-disseminating agents in Klebsiella spp. and emphasizes the need for constant surveillance of these pathogens to determine appropriate treatment strategies.