virulence genes and pulsed- field gel electrophoresis profiles of shiga toxin-producing escherichia coli isolated from different food samples and patients with acute diarrhea

Background and objectives: escherichia coli o157: h7 is one of the most important causes of hemorrhagic colitis, and hemolytic uremic syndrome. the present study aimed to isolate e. coli o157: h7 from foods and patients with hemorrhagic colitis, and identify shiga toxin genes, phylogenetic comparison, and antibiotic resistance of the isolates.materials and methods: in total 400 samples, including patients stool and food were taken in isfahan-iran province. phenotypic tests and pcr were performed to identify shiga toxin-producing e. coli. the isolated strains were compared phylogenetically by pfge. agar disk diffusion was performed to identify the antibiotic resistance of the isolates.results: totally, 5 isolates of fecal samples were e. coli o157, but only 2 isolates carried h7 gene. also, 9 isolates of e. coli o157 were isolated from food samples that 3 isolates were e. coli o157: h7. the isolates carried stx1, stx2, hlya and eaea genes. also, e. coli non-o157: h7 identified from samples that contained stx1, stx2, hlya genes. the highest susceptibility to imipenem and the highest resistance to ampicillin and ciprofloxacin were observed. there was a similarity of 100% between the e. coli o157: h7 strains isolated from patients and raw milk and minced beef samples.conclusion: serotypes other than the o157 of e. coli are more prevalent in patients and food. the e. coli o157: h7 isolates from patients had 100% genetic similarity with minced meat and cow milk isolates, which indicates cattle are the most important reservoir of this bacterium in iran.