Fig. 1 Agarose gel electrophoresis of PCR ampli®ed DNA from nontoxigenic Escherichia coli O157:H7 strain 3704 using H7, intimin and O157 PCR
primers. H7 gene product (625 bp); intimin (368 bp) and O157 (292 bp). Lanes: (A) negative control (no template); (B±F) E. coli O157:H7 strain
3704; (G) HyperLadder (Bioline, UK, Ltd)