comparison of two methods fordetection of e. coli o157h7 in unpasteurized milk

background and objectives: the most common serotype of enterohaemorrhagic esherichia coli group or shiga-toxin-producing e. coli is o157:h7. domestic and wild ruminants are regarded as the main natural reservoirs. o157:h7 serotype is the major cause of gastrointestinal infections in developed countries. in this study was conducted to survey on the toxigenic e. coli o157: h7 strains in milk of industrial dairy farms. materials and methods: a total number of 150 milk samples were collected from dairy industry in khuzestan, over a period of 6 months and were evaluated by cultivation in selective media (ct-smac) and multiplex pcr. results: two isolates were identified as e. coli using biochemical tests, none of them were toxigenic e. coli o157:h7 as determined by multiplex pcr. using direct pcr on milk samples, 45 samples contained at least one gene of the studied genes in this investigation ( rfb, flic, stx1 , stx2 ). with direct pcr, 2 milk samples were positive for toxigenic o157:h7. conclusion: e. coli o157:h7 is present in this region and so the necessity for strict compliance of health standards is recommended. this is the first study on o157: h7 e. coli milk contamination in khuzestan province. based on these results, direct pcr is more accurate than indirect pcr.