Isolation and identification of Escherichia coli O157:H7 from ground beef hamburgers in Khuzestan Province, Iran

Abstract

Meat products have been implicated in outbreaks of E. coli O157:H7 in most of the world. This bacterium is associated with diseases such as hemorrhagic colitis, hemolytic uremic syndrome and thrombotic thrombocytopenic purpura. In this study, we used two Conventional methods and Multiplex PCR for the isolation and identification of E. coli O157:H7 from ground beef hamburger samples. In total, 200 fresh ground beef hamburger samples were obtained from different meat factories across Khuzestan Province from March to September 2010. Tryptone- Soya- broth (TSB) supplemented with novobiocine (20 mg/l) was used as enrichment medium and Tellurite cefixime-sorbitol MacConkey agar (TC-SMAC) was used for the detection of Non-Sorbitol Fermenting bacteria. Biochemical tests were performed on the Non-Sorbitol fermenting (NSF) colonies. Colonies confirmed as E. coli were selected as templates for Multiplex PCR method and serotyping. Out of the 200 ground beef hamburger samples, 8 samples (4%) had positive results for Non-Sorbitol fermenting colonies (NSF). Out of the 8 samples, three (38%) were confirmed as E. coli by biochemical tests. Of the 3 samples, two samples were E. coli O157:H7 based on multiplex PCR and serotyping. The results indicate that hamburgers could be a reservoir of E. coli O157:H7 in Khuzestan Province. Since this strain is a food-born pathogen, inspection of meat products for this bacterium is recommended.