Frequency determination of blaTEM & blaSHV in the Extended-Spectrum Beta-Lactamase producing Escherichia coli isolates from Karaj

Background and Aim: Extended-spectrum β-lactamases are groups of enzyme with the capability of hydrolyzing cephalosporins and aztreonam. Various types of extended-spectrum β-lactamases (ESBLs), such as blaTEM and blaSHV are present prominently in E. coli strains. This study aimed to determine the frequency of blaTEM and blaSHV genes in the extended-spectrum β-lactamases, producing E. coli strains from urinary tract infections in Karaj city. Materials and Methods: In this study which performed during the summer of 2015, antibiotic susceptibility pattern of 119 isolated E. coli strains from urinary tract infections were determined to 16 different antibiotics using Kirby-Bauer disk diffusion method. Extended-spectrum β-lactamases-producing bacteria were identified using double disc diffusion method by combination discs and were studied by using specific primers for genes blaTEM and blaSHV. Results and Conclusions: The highest and lowest percentage of resistance to the antibiotic were tetracycline (61%) and nitrofurantoin (8.5%), respectively. 42.8% of isolates were extended-spectrum β-lactamases positive. Based on the PCR results the frequency of blaTEM and blaSHV were 60.78% and 39.21% respectively and 9.32% of isolates had both genes. High levels of genes blaTEM and blaSHV resistance to third generation of cephalosporins strains considered a problem. Diagnose of extended-spectrum β-lactamases strains in clinical laboratory also should be considered and it is recommended that prescription of cephalosporins should be restricted to susceptible isolates