Molecular typing of bla CTX M β-lactamase producing Escherichia coli from clinical isolates

Objective: Production of Extended Spectrum β- Lactamase is an important mechanism of antimicrobial resistance exhibited by Enterobacteriaceae. There are many types of ESBLs among which CTX M is a latest emerged one which carries the bla CTX M gene. CTX M lactamase producing Enterobacteriaceae are present in the intestinal flora without harming the host causing infection in extra intestinal sites. Transferring the gene through plasmids is responsible for the dissemination of antimicrobial resistant strains in the community. This study is designed to detect bla CTX-M gene in Escherichia coli isolates. Method: A total of 532 Escherichia coli isolates were screened for susceptibility testing. Isolates with decreased resistance to third generation Cephalosporins (3GC) were subjected to double disk synergy test for phenotypic confirmation of ESBL in which 178 were positive. Multiplex PCR was done for these 178 isolates to detect the four groups I, II, III & IV of CTX M. Results: Multiplex PCR yielded the products with predicted size for group 1 CTX M in 152 (28.57%) isolates. None of the isolates were positive for other groups of CTX M (Group II, III & IV) Conclusion: The presence of CTX M ESBL producing E. coli cause enormous problems in therapeutic interventions of infections which can be prevented only by continuous surveillance and prudent use of antibiotics.