Frequency of blaTEM، blaSHV, and blaCTX-M genes encoded extended-spectrum beta-lactamases in Escherichia coli isolates collected from groundwater in East Azerbaijan province in 2014

Escherichia coli is considered as the indicator of microbial contamination of water all over the world. This bacterium is able to produce extended-spectrum beta-lactamases (ESBLs) that is due to antibiotic resistance. Among them TEM, SHV and CTX-M are more abundant than others. The aim of this study was to determine the prevalence of beta-lactamase genes of E. coli isolated from qanats and springs.

Totally, 23 E. coli were isolated and identified by biochemical tests from 118 water sources in the East Azarbaijan province. In order to identify ESBLs by phenotypic methods, ceftazidime, cefotaxime, ceftazidime clavulanic acid, cefotaxime clavulanic acid antibiotic disks were used. In the next step blaTEM, blaSHV and blaCTX-M genes were detected in the isolates by PCR method.

Phenotypic methods showed only 2(9%) isolates were ESBL producer, while genotypic methods revealed that 9(39%), 10(43%) and 14(61%) isolates harbored blaTEM, blaSHV and blaCTX-M, respectively.

The results of this study showed that the high prevalence of beta-lactamase resistance among E. coli strains isolated from ground water sources. This is due to the spread of antibiotic resistance among pathogenic strains of E. coli with water sources.