Prevalence and Antimicrobial Resistance of DiarrheagenicEscherichia coliandShigellaSpecies Associated with Acute Diarrhea in Tehran, Iran

Abstract

A study was performed to determine the prevalence and antimicrobial resistance ofShigellaspecies and diarrheagenicEscherichia coliisolates cultured from patients with acute diarrhea in Tehran, Iran. Between May 2003 and May 2005, 1120 diarrheal specimens were collected and assayed for bacterial enteropathogens by conventional and molecular methods. Etiological agents were isolated from 564 (50.3%) specimens, and included 305 (54%)E coli, 157 (27.8%)Shigellaspecies, and 102 (18%) from other genera of bacteria. The predominantE coliwas Shiga toxin-producingE coli(105 isolates [34.5%]) and the predominantShigellaserotype wasShigella sonnei(88 isolates [56.1%]). A high rate of antibiotic resistance was observed amongE coli,with 40 of 53 (75.5%) Shiga toxin-producingE coliisolates resistant to amoxicillin and tetra-cycline, and eight (5.2%)E coliisolates resistant to more than six antibiotics. MostShigellaisolates were resistant to tetracycline (95%) and trimethoprim-sulfamethoxazole (91.7%), with greatest antibiotic resistance observed amongS sonnei(53 of 88 [60.2%] isolates). Antibiotic resistance is widespread in diarrheagenicE coliandShigellain children with acute diarrhea in Tehran, Iran; hence, updated strategies for appropriate use of antimicrobial agents in Iran are needed.