The occurrence of carbapenem resistance among Enterobacteriaceae has reached critical levels worldwide. The present study was carried out to screen for carbapenem resistance among Enterobacteriaceae isolates from blood, surgical wound and tracheal samples in different wards and intensive care units between the period of 2010 through 2012 in a teaching hospital attached to JIPMER, south India. A total number of 425 meropenem-resistant isolates belonging to Enterobacteriaceae were included. Genes encoding β-lactamases (blaNDM-1 and blaOXA-48) and influx of β-lactams through the major porin OmpK36 were characterized. Multiplex PCR amplification assays indicated that out of 425 meropenem- resistant isolates, 75 and 187 isolates harbored blaNDM-1 with and without OmpK36, respectively. One and five Klebsiella pneumoniae isolates harbored blaOXA-48 with presence and absence of OmpK36, respectively. Transferability of the plasmids was tested by conjugation assays and it was found that 110 transconjugants carried blaNDM-1. blaOXA-48 gene was not transferable by conjugation analysis. The study highlights the emergence of blaNDM-1 and blaOXA-48 genes in this center.
Key words: Enterobacteriaceae; blaNDM-1; blaOXA-48; OmpK36; conjugation.