Isolation, Identification and Virulence Gene Profiling of Escherichia coli O157:H7 in Retail Doner Kebabs, Iran

Abstract

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