Background: Third generation Cephalosporins resistances among Escherichia coli due to production of ESBL, mainly the bla-CTX-M, bla-TEM and bla-SHV genes, poses serious challenges in the clinical utility of these drugs in healthcare settings. This study was undertaken to detect prevalence of ESBL producing MDR E. coli isolates by various phenotypic and molecular method from in or out patients with urinary tract infection (UTI). Methods: A total of 56 non-repetitive isolates of E. coli from in or out patients of UTI were subjected to antimicrobial susceptibility testing. Screening for the production of extended-spectrum β-lactamases (ESBL) was determined in third generation Cephalosporins resistant isolates by minimum inhibitory concentration (MIC) E-strip, followed by phenotypic confirmation by DDST, CDST and ESBL E-strip method. Further confirmation was done by molecular method, PCR was carried out for detection of bla-CTX-M, bla-TEM and bla-SHV. Results: All strains (56/56) were observed as ESBL producers by MIC E-strip method, 94.64% (53/56) isolates were observed as ESBL producer by DDST and 67.86% (38/56) were observed by CDST. The overall ESBL production among all MDR E. coli isolates was 89.29% (50/56) which includes any one of the three genes. The prevalence of bla-CTX-M (80.36%, 45/56) was highest, followed by bla-TEM (50%, 28/56) and bla-SHV (10.71%, 6/56). Conclusion: In our study we found bla-CTX-M gene is predominantly circulating among all three ESBL genes in the clinical isolates of MDR E. coli that were producers of ESBL.
Datt et al. (Fri,) studied this question.