During the spring of 2008 a number of 120 swab samples were taken from brisket region of male cattle carcasses in the range of 2-4 years of age, which were slaughtered in Mashhad abattoir. The samples were obtained from the post-chilling stage of processing. The samples were initially enriched in modified trypticase soy broth containing novobiocin, followed by plating on sorbitol Mac Cankey agar supplemented with cifixime and potassium tellurite. Consequently, the suspected non sorbitol fermenting (NSF) colonies were confirmed by biochemical tests as Escherichia coli and then employed for multiplex-PCR (m-PCR) assay. In the first m- PCR assay, primers specific for O157 and H7 antigens gene were used. A total of 10 NSF Escherichia coli colonies were isolated and in the m-PCR assay 8(6.6%) of the samples were confirmed as Escherichia coli O157:H7. The second m-PCR assay showed number of two isolates harboring the Shiga toxin (stx2) gene. The m-PCR assays employed in this study might be considered as a possible alternative approach for immunological assays which detects somatic and flagellar antigens. Besides this method determines potential of shiga toxin production.

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