Seasonal Effects on E. coli O157:H7, Multi Drug-Resistant Salmonella, and Listeria monocytogenes Prevalence and E. coli O157:H7 and Salmonella Load on Hides and Carcasses at Cow/Bull Packing Plants

Findings: Preventing the contamination of ground beef with pathogens such as E. coli O157:H7, multi-drug resistant (MDR) Salmonella, or Listeria, which can lead to outbreaks of food-borne illness, is a high priority for the meat industry as well as consumers. Meat from cow/bull processing plants makes up a significant proportion of ground beef, yet little is known about the prevalence of food-borne pathogens on the hides and carcasses of cull cows and bulls. In this study, we evaluated the prevalence and load of E. coli O157:H7, Salmonella, MDR Salmonella and Listeria on the hides and carcasses of cull cows and bulls at slaughter. We found levels of Salmonella on hides and carcasses to be consistently higher than E. coli O157:H7 and Listeria. The multi-drug resistance status of the Salmonella isolated in this study is being assessed. Preliminary data (from 1 of the 4 seasons, Winter 2006) indicates that the percent of MDR Salmonella present on hides and carcasses varies considerably. These data demonstrate that food-borne pathogens are present on the hides and carcasses of cow/bull cattle at slaughter, but that carcass interventions in general, greatly reduce the prevalence and levels of Salmonella, MDR Salmonella and Listeria on final carcasses.