Molecular epidemiology of clinical isolates of ampc producing Klebsiella pneumoniae

AmpC producing K. pneumoniae have been increasingly reported from India but epidemiological studies are lacking. In the present study, molecular epidemiology of extended-spectrum AmpC beta-lactamases (ESACs) producing clinical isolates of K. pneumoniae prevalent in our hospital was studied.Fifty-one non-repeat, consecutive, clinical isolates of K. pneumoniae producing AmpC enzymes, were subjected to whole cell protein profile analysis (SDS-PAGE) and ribotyping. The antimicrobial susceptibility was determined using standard disk diffusion technique. The isolates showing decreased susceptibility to cefoxitin (18 mm) or cefotetan (16 mm) were subjected to modified three- dimensional test for detection of AmpC enzyme.Six different types of protein profiles were observed. Ribotyping could further discriminate between the strains that were clustered by protein fingerprinting. Twelve different ribo-patterns were identified. Ribotyping was found to have a better Discriminatory Index (0.98) than that of SDS-PAGE (0.78). Of the 26 isolates that showed decreased susceptibility to cefoxitin and/or cefotetan 13 isolates were found to harbour AmpC enzyme.The study demonstrated the usefulness of SDS-PAGE whole cell protein profile analysis and ribotyping to identify the clonality of the ESACs isolates, the latter having a higher discriminatory power. The presence of ESACs isolates in the community as well as in hospital settings emphasizes the need for regular monitoring of antimicrobial resistance.