Evaluation of thin agar layer method for recovery of heat-injured foodborne pathogens

The Thin Agar Layer /TAL) method of Kang and Fung 1998 was used to enumerat e heat-injured (55 degreesC for 10 min) foodborne pathogens. This method in volves overlaying 14 mL, of nonselective medium (Tryptic Soy Agar, TSA) ont o a prepoured, pathogen-specific, selective medium. The recovery rate with the TAL method was compared with the rate for TSA and pathogen-specific, se lective media. No significant differences occurred between TSA and TAL (P > 0.05) for enumeration of heat-injured Escherichia coli O157:H7, Listeria m onocytogenes, Salmonella typhimurium, Staphylococcus aureus, and Yersinia e nterocolitica, and both recovered significantly higher numbers than selecti ve media (P < 0.05). The TAL method is a 1-step, convenient procedure for r ecovery of heat-injured cells.