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

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.
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 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.