Antibiotic Resistance Pattern and Genotype of Beta-Lactamase Producing Escherichia coli Isolates from Urinary Tract Infections in Zabol-Souteast of Iran

Introduction: Extended spectrum beta-lactamase (ESBL) producing Escherichia coli generate a major problem for clinical therapeutics and epidemiological study. The incidence of ESBL producing strains among clinical isolates has been steadily increasing during the past few years, and remains an important cause of failure of therapy with cephalosporins. The aim of this study was to determine the antimicrobial susceptibility pattern and prevalence of ESBLs in E. coli isolates taken from different clinical specimens by phenotypic and genotypic techniques. Methods: In this descriptive study, a total of 100 E. coli isolates collected from different clinical specimens were used. The antibiotic resistance pattern to twelve antimicrobial agents was determined by disk diffusion method. The ESBLs producing strains were confirmed by double-disk-diffusion test, and the CTX-M, TEM, SHV, and OXA were detected by PCR. Results: The prevalence of ESBL producing E. coli was 56%. The results show that 95% of ESBL producing E. coli isolates tested were resistant to ceftriaxone and cefotaxime, 93% to ceftazidime, 86% to azithromycin, 79% to cefazolin and 43% to imipenem. Among the ESBL producing E. coli, 48%, 30% and 11% were positive for CTX-M, TEM and SHV genes, respectively. OXA was not found in all isolates. Conclusion: ESBL producing isolates of E. coli have been increasingly recognized and there is a need to carefully formulate therapeutic strategies to control infections in teaching Hospitals. The high percentage of drug resistance in ESBL producing E. coli suggests that routine detection of ESBL is required by reliable laboratory methods.