Prevalence of CTX-M Genes in Escherichia Coli Strains in Outpatient and Inpatient Cases with Urinary Tract Infections in Isfahan, Iran

Extended-spectrum beta-lactamase of CTX-M-type is considered as an important mechanism resistant to beta-lactam drugs in the gram-negative pathogens. In this study, the prevalence of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (E. coli) as well as the frequency of CTX-M genes from urinary tract infections in inpatients and outpatients caused by Escherichia coli in selected health centers in Isfahan, Iran, was studied in 2013. The study was carried out on 120 E. coli isolates from inpatients and outpatients with urinary tract infection. The susceptibility of isolates was tested using disc diffusion method. The ESBL-producer strains were confirmed using combined discs method. Finally, the blaCTX-M gene was determined in ESBL-producer isolates using polymerase chain reaction (PCR) method. To identify the strains of E. coli producing CTX-M genes, PCR method was used. The collected data were entered and analyzed in WHONET 5.6 and Excel softwares. From 120 strains of E. coli, 12 outpatient (20.0%) and 33 inpatient (55.0%) isolates were ESBL-producer. 84.4% and 60.1% of outpatient isolates and 94.9% and 84.8% of inpatient isolates showed resistance to ampicillin and co-trimoxazole, respectively. PCR analysis revealed that 30 isolates had CTX-M gene. The production of ESBL, in particular in isolates of inpatients, is a big threat for use of the broad-spectrum cephalosporins. Given the presence of CTX-M gene in the high proportion of the isolates, more molecular and epidemiological studies on pathogenic bacteria in health centers is required to be able to have a common plan to control bacterial resistance.