Most illnesses caused by Escherichia coli O157:H7 have been associated with eating undercooked, contaminated meat. In this study, a number of 200 cooked beef doner kebab samples from different restaurants across cities of Tehran and Mashhad were analyzed. After enrichment, selective plating and biochemical tests, the DNA from suspected colonies were extracted. Three multiplex polymerase chain reaction (PCR) assays to confirm the isolates as E. coli O157:H7 and the presence of virulence factors were performed. Specific primers for cH7 and rfbO157 genes in the first and for stx1 and stx2 genes in the second m-PCR were used. The third m-PCR performed using specific primers for eaeA and EhlyA genes. From 25 nonsorbitol-fermenting isolates, 21 isolates confirmed as E. coli O157:H7. The results of third m-PCR showed 12 isolates harboring the EhlyA gene, three isolates the eaeA gene and three isolates harboring both the EhlyA and eaeA genes. PRACTICAL APPLICATIONS The presence of Escherichia coli O157:H7 in cooked beef doner kebabs could be considered a serious public health hazard. These three multiplex PCR assay are a suitable method for rapid identification of E. coli O157:H7 virulence genes.

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