Phenotypic and molecular characterization of CTX-M extended-spectrum beta-lactamase-producing Escherichia coli isolates in Shiraz, Iran

Abstract

Introduction: The aim of this study was to detect the prevalence of the extended-spectrum beta-lactamase (ESBL)- encoding CTX-M gene in Escherichia coli isolates. Methods: Phenotypic screening of 376 E. coli isolates for ESBL was conducted using disk diffusion. ESBL-producing isolates were tested using PCR and specific primers. The blaCTX-M cluster was identified using the RFLP method, and its genotype was sequenced. Results: From 202 ESBL-producing E. coli, 185 (91.5%) possessed CTX-M genes. CTX-M-1 subtypes were found in 98% of the isolates. The blaCTX-M gene was identical to CTX-M-15. Conclusions: A high prevalence of CTX-M-1-producing E. coli apparently exists in Shiraz, Iran.