This study investigated the effects of heat shock and post-heat environmental conditions on the survival of Escherichia coli ATCC 25922 at 52, 54 and 56°C. Significantly (P Salmonella enteritidis and E. coli, respectively. However, a fluid thioglycollate medium overlay of spread plates significantly decreased the D-values of E. coli ATCC 25922 at 52, 54 and 56°C. When the fluid thioglycollate medium was used to overlay pour plates, no significant changes in D-values were seen.