INTERVENTIONS TO REDUCE FOODBORNE PATHOGENS IN SWINE AND CATTLE

1. Determine particular ecological niches/reservoirs for pathogenic/antimicrobial-resistant bacteria, identifying nutritional/biological/environmental factors affecting ability to colonize/survive/persist within gut of food-producing animals & their production environment. a) Determine effect of feeding distillers grains & other diets & organic acids on gut microbial ecology; b) Determine effects of feeding diets high in rumen undegradable intake protein & of feeding monensin on colonization/carriage/shedding of Campylobacter in cattle; c) Evaluate mechanistic effects of short chain nitrocompounds & free fatty acids on hydrogen balance/fitness of foodborne pathogens; d) Determine if specific or shared reservoirs exist for Clostridium difficile in populations of swine & humans in integrated agri-business operations; phenotypically/genotypically characterize Cl. difficile isolates; e) Determine effects of lactoferrin & whey-protein concentrate on fecal shedding & gut populations of Salmonella Typhimurium in weaned piglets; f) Determine influence of vitamin D supplement on fecal prevalence/concentrations of E. coli O157:H7 in cattle. 2. Evaluate ways to better characterize/control Salmonella, in particular multi-drug-resistant Salmonella, for use on commercial dairy farms to enhance food safety. a) Develop Salmonella serotype-specific real-time PCR method; b) Determine if Salmonella serotype changes due to changing environment or acquisition of antimicrobial resistance; c) Determine if feeding sodium chlorate, with/without nitroethane, is effective in reducing populations of Salmonella as well as E. coli O157:H7 & generic E. coli in milk-replacer fed calves & cull dairy cattle. 3. Develop interventions that prevent/mitigate colonization of gut of food-producing animals (particularly lower GI tract before slaughter) or that reduce pathogenic/antimicrobial-resistant bacteria in production environment. a) Determine if porcine-derived competitive exclusion culture can stimulate innate immune responses in neonatal gnotobiotic piglets; b) Develop/characterize bactericidal effectiveness of thymol & diphenyliodonium chloride products bound to clay-based adsorbents; c) Establish feasibility of fresh/dried citrus peel & purified essential oils as feed additives to reduce pathogen populations in ruminants; d) Develop targeted management interventions to facilitate exclusion of antimicrobial-resistant bacteria from gut of treated animals. 4. Develop understanding of microbial adaption to intrinsic/extrinsic stressors on acquisition/exchange/expression of incompatibility plasmids & antimicrobial resistance elements in foodborne pathogens in production/processing environments. a) Determine if number/size of plasmids possessed by different wildtype E. coli affects growth rate in nonselective & mixed culture environments, and if these plasmids are lost during long-term maintenance without selection pressure; b) Determine if IncN/Incl1 can mobilize IncA/C in tri-parental conjugations; c) Determine if occurrence of bacterial resistance to disinfectants is important in disinfectant control or impacts antibiotic resistance in microorganisms of animal origin.