Heat Resistance of Salmonella Serotypes (Including Multi Drug-Resistant and Non Multi-Drug Resistant) on Beef Exposed to Consumer-Style Cooking

Findings: A comparative study was undertaken to determine the heat resistance of different Salmonella serotypes commonly isolated from beef and/or cattle and their environments as well as the difference in heat resistance of multi-drug resistant and nonmulti-drug resistant Salmonella strains of each serotype. The reason for conducting this work is to identify particular serotypes with higher heat resistance than other commonly-found serotypes as their occurrence on beef, especially ground beef that is often undercooked, would pose a greater public health risk. Furthermore, it is necessary to determine if the degree of drug (antibiotic) resistance affects the heat resistance of such serotypes. Results of this research indicated that two serotypes in particular, S. Anatum and S. Agona, had substantially higher heat resistance compared to the serotypes evaluated including the commonly-isolated S. Typhimurium, S. Newport, and S. Montevideo. Furthermore, there was no substantial difference in heat resistance of multi-drug compared to nonmulti-drug resistant strains of Salmonella. This implies that serotype rather than the drug-resistance profile of Salmonella is more important in risk assessment of the pathogen. Survival studies of the most resistant serotypes identified in this work indicated that S. Agona was able to survive in ground beef cooked to an internal temperature of 71ºC.