95 degree C for 5 min, 25 cycles, each cycle consisting of 94 degree C for 30s, 54 degree C for 30s and 72 degree C for 30s, plus a final extension step at 72 degree C for 10 m. The expected size of PCR amplicon was 306bp for stxl, 482 bp for stx2, 254bp for eae, 138bp for ehxA.