MOLECULAR CHARACTERISATION OF PLASMID MEDIATED AMPC BETA-LACTAMASE IN THE CLINICAL GRAM NEGATIVE BACTERIAL ISOLATES FROM CHENNAINIBEDITA DEY, SUBHASHREE YASOBANTI, MAGESH H., RAMA VAIDYANATHAN, CHOZAHAVENDHAN S. ROSY VENNILA AND KAMATCHI C.
An increased resistance to clinically effective antibiotics has been reported in Gram negative bacteria. The increase in drug resistance has been attributed to the spread of plasmid containing antibiotic resistance genes. This study was undertaken to analyse and identify phenotypic and genotypic detection of plasmid-mediated AmpC beta-lactamase in the clinical Gram negative isolates in Chennai. Sixty four clinical isolates were collected from Chennai during the period 2011- 2012 and their resistance pattern was analysed by the antimicrobial Susceptibility test. It was observed that 98.4% resistant to amoxyclav, and 81.2% to cefotaxime, a third generation cephalosporin. Seventeen isolates (26.5%) were resistance to cefoxitin and subsequently only 8 isolates were sensitive to boronic acid test. Only two isolates were found to contain plasmid mediated blaCMY-6 gene and which was confirmed by sequencing. MIC for amoxyclav were performed and MIC ranges was from 12.5μg/mL to 100μg/mL. However, the amoxyclav MIC values were high for those isolates harbouring blaNDM-1 gene. Imipenem MIC values ranges from >1250μg/mL to 625μg/ mL and all four imipenem resistant isolates were harbouring blaNDM-1 gene which was proved genotypically. However the plasmids were transformed into E.coli JM109 and proves the plasmid mediated resistance. In our study, the presence of plasmid mediated AmpC Beta-Lactamase in Gram negative isolates was confirmed the presence of blaCMY-6 gene.
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