identification of different escherichia coli pathotypes in north and north-west provinces of iran

background and objectives: diarrhea is one of the most prevalent diseases in the world, specially in developing countries. one of the most important causative agents of bacterial diarrhea is diarrheagenic escherichia coli (dec) which causes gastroenteritis and this group involving enterotoxigenic e. coli (etec), enteropathogenic e. coli (epec), enteroaggregative e. coli (eaec), enterohemoragic e. coli (ehec), enteroinvasive e. coli (eiec), diffusely adherence e. coli (daec). the aim of this study was to identify different e. coli pathotypes in north and north-west of iran, among the clinical isolates. materials and methods: in this study for identification of e. coli , 170 fecal samples were cultured on macconkey agar and identified by biochemical tests. samples with e. coli characteristics were selected (145 samples) and their genomes were purified by phenol-chloroform method. after extraction of genomes, lt and sta genes identified by pcr for etec, eae gene for atypical and eae and bfp for typical epec, aa region for eaec, stx 1 and stx 2 and eae genes for ehec ( stx 1 or stx 2 or both for stec) and inve for eiec. results: finally 10 samples identified as etec (%5.88), 18 (%10.58) epec, 6 (%3.52) ehec and 12 (7.05%) samples were stec. none of the samples were positive for eaec and eiec. conclusion: the results obtained in this study showed that etec, epec, ehec and stec are prevalent bacterial agents in north and north-west of iran. complementary studies to identify these pathotypes in other seasons can help to adopt necessary policies against outbreaks in iran.