Detection and Molecular Characterization of ESBLs in E. coli Isolates from a Tertiary Care Hospital in North India with Special Attention to CTX-M-27

Background: Extended spectrum beta-lactamases are the main cause of resistance to beta lactam antibiotics in members of Enterobacteriaceae. ESBL associated infections are on a rise worldwide and have become a serious public health problem. We aimed to investigate the molecular epidemiology of ESBL producing E. coli isolates recovered from various clinical specimens at a tertiary care hospital and to determine the antibiotic sensitivity profile of ESBL positive isolates.

Methodology: A total of 300 isolates of E. coli were collected from various clinical specimens between the study period of 2011 to 2014. Antimicrobial susceptibility testing was done. ESBL detection was carried out by CLSI Phenotypic confirmatory method. Molecular typing of ESBLs was performed by uniplex PCR among 100 ESBL isolates. The bla CTX-M strains were genotyped by sequencing of PCR product. Nucleotide sequences were submitted to Gen Bank and accession numbers were obtained.

Results: 61% isolates were found to be ESBL producers. ESBL and non-ESBL producers compared among in- and out-patients gave statistically significant result (P value=0.002). All ESBL isolates (100%) were sensitive to imipenem. Overall 93.9% ESBL producers and 67.5% non-ESBLs were Multi Drug Resistant (Resistance to 3 or more class of antibiotics). The difference was statistically significant (P value=0.001). Majority of the typeable isolates harboured two or more ESBL genes (52%). Sequencing was done for 10 randomly selected blaCTX-M PCR products and majority (90%) were identified as CTXM-15 belonging to CTX-M Cluster-1 while 1 0f 10 (10%) was identified as CTX-M- 27 belonging to CTX-M Cluster-9 on blast analysis. Deduced nucleotide sequences were submitted to Gen Bank. The accession numbers obtained from Gen Bank are KU946005-KU946009.

Conclusion: Our study shows high ESBL occurrence among E.coli isolates and highlights the incidence CTX-M-27 for the first time from North India.