isolation and molecular characterization of non-sorbitol fermenting escherichia coli isolated from fresh ground beef

Background: escherichia coli o157:h7 (ehec) has been traditionally associated with foodborne infections from consumption of foods with animal origin such as ground beef and burgers. objectives: the objective of this study was to investigate the contamination of fresh ground beef with non-sorbitol fermenting escherichia coli and presence of virulence genes in isolates obtained from butchers located in ahvaz, iran. materials and methods: a total of 200 fresh ground beef were sampled during a six-month period. all samples were enriched in tryptic soy broth (tsb) with novobiocin and plating on cefixime telluride-sorbitol macconkey (ct-smac). the suspected colonies were subjected to polymerase chain reaction (pcr) analysis to identify virulence genes containing rfbe o157, flic h7, stx1 and stx2 genes. results: overall, 1.5% of ground beef samples were contaminated with the o157 e. coli strain meanwhile 1% of samples contained the o157:h7 strain and 0.5% of samples had the o157:h7 with virulent stx1 and stx2 genes. conclusions: the observed results indicated the necessity of good care in abattoir, butcheries and during food distribution, mainly ground beef. also, a zero tolerance policy could be useful to control e. coli o157 in meat products nationwide.