Pathogen Mitigation in Livestock and Red Meat Production

Approach:
<br/>The research to be conducted in this project will focus on Shiga-toxin producing E. coli (STEC) and Salmonella at multiple stages of the beef production continuum and contains both basic and applied aspects. The research objectives have been divided into classifications of antimicrobial intervention, detection methodology, and host-pathogen interaction. Antimicrobial interventions to be investigated include applications for the live animal and for carcasses during harvest. Feed supplements will be studied as a means of reducing E. coli O157:H7 in feedlot cattle. Feed supplements are more easily administered than other potential preharvest interventions, such as vaccines, and may provide cross protection against a variety of pathogens. As the hide has been shown to be the source of carcass contamination at processing, any reduction in hide pathogen load should result in lower carcass contamination rates. Thermal dehairing will be investigated as a means to sanitize the cattle hide prior to hide removal. Work will be done to evaluate application of bacteriophage to the hide of the live animal just prior to entrance into the processing plant as an additional step to reduce carriage of E. coli O157:H7 on the animal’s hide. Basic research to model the colonization of E. coli O157:H7 at the bovine recto-anal junction will allow for in vitro assay development to identify direct methods of colonization disruption and mitigation to reduce or eliminate the pathogen from the gastrointestinal tract of cattle. Non-O157 STEC are becoming an increasing burden on beef production with potential regulatory policy based on these organisms. The project described herein will endeavor to develop and validate methodologies for the detection of non-O157 STEC that will provide the beef industry with more sensitive and specific tools to combat these pathogens. While STEC contamination of beef carcasses occurs predominantly through transfer of the pathogens from the hide of the animal to the carcass as the hide is removed, Salmonella contamination has been shown to reside within the tissues of the animal. Previous work has shown that Salmonella can be isolated from lymph nodes located within meat cuts destined for human consumption. Experiments have been designed to study the dissemination of Salmonella in bovine lymph nodes throughout the animal during an active infection and after clinical symptoms have subsided.