Using multiplex-PCR assay in identification of Escherichia coli O157:H7 isolated from hamburger samples in Mashhad, Iran

In this study a number of 100 hamburger samples which were produced industerially from different batches were collected randomly from suprermarkets in Mashhad city، during the autumn months of 2006. For isolation of the bacteria، samples were، firstly 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 assay، using primers specific for O157 and H7 antigens gene. The m-PCR assay employed in this study may be a possible alternative to immunological assays which detects somatic and flagellar antigens. In this study، 9 NSF Escherichia coli colonies were isolated، and in multiplex-PCR assay two samples (4%) were confirmed as Escherichia coli O157: H7.