Shiga toxin-producing Escherichia coli (STEC), also called verotoxin-producing E. coli (VTEC), have emerged as an important food-borne pathogen (Karmal, 1989). Especially O157:H7 serotype has attracted significant attention because of its low infectious dose (Buchanan and Doyle, 1997). Gastroenteritis caused by this bacteria, may be lead to some life threatening conditions such as hemorrhagic colitis (HC), hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP) (Karmal, 1989). Ca l e are one of the main principal reservoirs of E. coli O157:H7 (Langreid et al., 1999; Cobbold and Desmarchelier, 2000). Failure to implement proper sanitary conditions at farm, abattoir or retail outlets usually facilitates transfer of enteropathogenic E. coli to meat and its associated food products (Radu et al., 2001; Bo e ldoorn et al., 2003; Tutenel et al., 2003). In the present study, 100 E. coli isolates from healthy calve feces were examined for detec o n of STEC strains. Duplex PCR assay was used in order to determine the presence of the stx1, and stx2 genes. The stx1 or stx2 posi v e isolates was later analyzed with primers specific for eae, hly genes. PCR assay was also conducted on these isolates for detec o n of O157: H7 serotype. Our results showed that 15 isolates (15%) were posi v e for stx1 gene, 19 isolates (19%) were posi v e for stx2 gene and 8 isolates (8%) were posi v e for both stx1, and stx2. Totally 26 isolates were posi v e for at least one of stx1or stx2 genes. Among 26 isolates, which were tested for the presence of eae and hly genes, 5 and 22 of them were posi v e for these genes, respec v ely. Four isolates were posi v e for both eae and hly genes. Among 26 isolates which were analyzed for genes coding O157 and H7 antigens, one and four isolates were posi v e for O157 and H7 an g en gene, respec v ely. None of the isolates were positive for both antigen genes. Regarding the results of the present study, healthy calves can act as important reservoirs of STEC strains for human. Development of strict sanitary condition for food animal husbandry is one of the main approaches to decrease the dissemination of these pathogens

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