No abstract

A study was performed to determine the prevalence and antimicrobial resistance of Shigella species and diarrheagenic Escherichia coli isolates 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%) Shigella species, and 102 (18%) from other genera of bacteria. The predominant E coli was Shiga toxin-producing E coli (105 isolates [34.5%]) and the predominant Shigella serotype was Shigella sonnei (88 isolates [56.1%]). A high rate of antibiotic resistance was observed among E coli, with 40 of 53 (75.5%) Shiga toxin-producing E coli isolates resistant to amoxicillin and tetra-cycline, and eight (5.2%) E coli isolates resistant to more than six antibiotics. Most Shigella isolates were resistant to tetracycline (95%) and trimethoprim-sulfamethoxazole (91.7%), with greatest antibiotic resistance observed among S sonnei (53 of 88 [60.2%] isolates). Antibiotic resistance is widespread in diarrheagenic E coli and Shigella in children with acute diarrhea in Tehran, Iran; hence, updated strategies for appropriate use of antimicrobial agents in Iran are needed.

Background:During the last decade, the prevalence of foodborne diseases due to contaminated food as well as the outbreaks of diseases due to Shiga toxin-producing Escherichia coli (STEC) strains has increased.Objectives:The aim of this study was to evaluate the prevalence and antibiotic resistance pattern of STEC strains in lettuce samples. Since lettuce is used as a raw vegetable in salads, the rates of infections caused by this vegetable are high.Materials and Methods:A total of 100 samples collected from Tehran, Iran, were transported to the laboratory, homogenized by a stomacher in E. coli broth containing cefixime, and cultured on MacConkey agar medium. Their DNA was extracted by boiling method and polymerase chain reaction (PCR) was performed, using five primers targeting the stx1, stx2, fliCh7, rbfO157, and eaeA genes. Susceptibility testing against ampicillin, imipenem, cephalosporin, tetracycline, aminoglycosides, chloramphenicol and quinolones was performed using disk diffusion method.Results:Eight samples were positive for presence of STEC strains, three contained stx1, five contained stx2, and one sample was positive for presence of both rbfO157 and fliCh7. They were susceptible to all the antibiotics except for ampicillin and tetracycline.Conclusions:This study indicated the contamination of lettuce by STEC strains and its possible role as the source of infection. Resistance to both tetracycline and ampicillin may be considered as an emergency alarm for a multidrug resistance of STEC strains.

From July to December 2003, four categories of diarrhoeagenic Escherichia coli were investigated in Tehranian children with acute diarrhoea. Stool specimens of children under 5 years of age with diarrhoea (n=200) and matched controls (n=200) without diarrhoea were studied for the presence of entero-aggregative (EAEC), enteropathogenic (EPEC), enterotoxigenic (ETEC) and Shiga toxin-producing (STEC) E. coli by PCR identification of six different genes of diarrhoeagenic E. coli. STEC isolates were typed by O157 and H7 antisera. EAEC was the most prevalent category and was found in 24% of patients with diarrhoea and 8% of controls (p<0.0001). ETEC was isolated in 15.5% of patients with diarrhoea but not in any controls ( p<0.0001), STEC in 15% of patients and 2% of controls (p<0.0001) and EPEC in 6% of patients and 5% of controls. Of 30 STEC isolates from patients with diarrhoea, seven were O157:H7 and 23 were non-O157:H7.

No abstract