Suitability of selective media for recovery of heat-stressed Escherichia coli O157:H7

Tryptone soya agar (TSA) and three selective media; BCM(TM) O157:H7(+) agar (BCM), modified eosin methylene blue agar (MEMB), and sorbitol MacConkey agar (SMAC) were evaluated for recovery of two strains off. coli O157:H7 (salami and cider isolates) heated at 56 58, and 60C for up to 60 min in tryptone soya broth (TSB). TSA and MEMB were equally effective at recovery of heat-stressed (56 58, and 60C) E. coli O157:H7 and superior to SMAC and BCM (P less than or equal to 0.05). When heated at 56 and 58C, recovery off. coli O157:H7 on MEMB and TSA was not significantly different (P > 0.05); recovery was poorer an SMAC, followed by BCM(P less than or equal to 0.05). There was no significant difference in recovery off. coli O157:H7 on BCM and SMAC when strains were heated at 60C (P > 0.05).