Project : USDA ARS

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Research Project: Ecological Reservoirs and Intervention Strategies to Reduce Foodborne Pathogens in Cattle and Swine

Location: Food and Feed Safety Research

2018 Annual Report

Objectives
Objective 1: Identify the ecological niches or reservoirs for pathogenic and antimicrobial resistant foodborne bacteria and determine nutritional, immunological, biological and environmental factors impacting their ability to colonize, survive, and persist in the gut and environment of food producing animals using metagenomic and molecular characterization of competitiveness, resistance and virulence. 1.A: Determine the effect of dietary components, feedstuffs, phytochemical extracts, and organic acids on the intestinal microbiome and functional genomics of the gut, and the impact of these changes on enterohemorrhagic E. coli and Salmonella. 1.B: Characterize the effects of short chain nitrocompounds on hydrogen ecology, pathogen competitiveness and gene expression in E. coli, Salmonella, and Campylobacter. Objective 2: Characterize the biological factors affecting infection and maintenance of Salmonella in lymphatics of food producing animals and elucidate management practices to mitigate infection. 2.A: Determine the duration of Salmonella infection in the peripheral lymph nodes of cattle. 2.B: Determine the role of mucous membranes in uptake and distribution of Salmonella to the peripheral lymph nodes of cattle. 2.C: Determine the prevalence, antimicrobial susceptibilities, genetic relatedness, serotypes, and molecular characteristics of Salmonella isolated from head meat and trim intended for ground pork. Objective 3: Identify, develop, and test interventions, including exploring possible synergies of multiple interventions and alternatives to antibiotics that can kill pathogenic or antibiotic resistant foodborne pathogens or mitigate their virulence and resistance in the animal production environment. 3.A: Enhance the effectiveness of naturally occurring phytochemicals and organic acids in reducing E. coli and Salmonella in the animal gut. 3.B: Reduce-to-practice ß-D-thymol as a feed additive prebiotic pathogen control technology for swine. 3.C: Determine if feeding sodium chlorate will reduce populations of Salmonella within the peripheral lymph nodes. 3.D: Determine if application of a bacteriophage cocktail will reduce or eliminate Salmonella from the peripheral lymph nodes of experimentally-infected cattle. 3.E: Determine if killed, irradiated, or spent chemostatic effluent of a recombined porcine-derived competitive exclusion culture can stimulate in vitro and in vivo immune responses and characterize the production and efficacy of biofilms and bacteriocins associated with the culture. Objective 4: Investigate the ecology of antimicrobial and disinfectant resistance within the gut of food producing animals and their production environment and elucidate factors contributing to the acquisition, exchange, dissemination and maintenance of resistant elements in foodborne pathogens and commensal bacteria. 4.A: Determine association between multidrug resistance (MDR) and virulence traits in Escherichia coli and non-typhoidal Salmonella enterica serovars isolated from food producing animals that might provide a dissemination advantage.

Approach
Basic and applied research will be conducted to achieve project objectives. Studies employing metagenomic analysis will elucidate ecological niches or reservoirs where pathogens may exist, and when combined with traditional epidemiological and microbiological cultural methods, these studies will help reveal environmental, nutritional, and biological factors affecting fitness characteristics contributing to persistent colonization, survival, and growth of these pathogens in food animals and their production environment. Research involving both in vitro and in vivo methods will be used to assess and characterize adaptive responses microbes may exhibit to intrinsic and extrinsic stressors, such as those exerted by disinfectants and antimicrobials, as well as to learn how these stressors may influence pathogenicity, virulence, and resistance of the microbes. Animal studies conducted under clinical and field situations will be used to develop and evaluate interventions, thereby revealing specific metabolic endpoints, cellular mechanisms, and sites of action of cellular processes that may ultimately be exploited to decrease carriage and shedding of pathogens during production and at slaughter. When applicable, Cooperative Research and Development Agreements will be implemented with industry partners to aid in technology transfer.

Progress Report
Work under the project during FY 2018 resulted in significant progress in identifying critical control points for the application of new and improved intervention needs by providing new knowledge on routes of Salmonella infection (Objective 3) and mechanisms of antimicrobial resistance dissemination (Objective 4). Project work has continued ongoing efforts aimed at the development of practical, cost-effective interventions and management practices to reduce the carriage and environmental dissemination of pathogenic and antimicrobial-resistant microbes by food-producing animals (Objectives 1 and 2). Where practical, these interventions are being designed to contribute to the efficiency and profitability of animal production; industry partners are collaborating to facilitate implementation of these technologies. New technologies and protocols developed from this work will help U.S. farmers and ranchers produce safer, more wholesome meat products at less cost to the consumer.

Accomplishments
1. A new natural antibiotic alternative for swine. Livestock farmers are under increasing pressure to reduce their use of antibiotics to control disease during production; consequently, there is need for new technologies to help farmers maintain optimal health and well-being of their animals. ARS scientists at College Station, Texas, in collaboration with scientists at the Norman E. Borlaug Institute for International Agriculture, determined the efficacy of the plant, Nigella sativa (black cumin), as a potential substitute for conventional antibiotics currently used in swine production. The work established that feeding black cumin dramatically improved growth efficiency of the pigs and helped them resist colonization by the bacterium, Escherichia coli, which is particularly pathogenic for young pigs. These results provide important information on a potential new feed additive that, when combined with other feed ingredients and good management, can help pig farmers improve the health and well-being of their young animals. Ultimately, these results will help pig farmers find new ways to safely and economically produce high quality and wholesome pork products at less cost to the American consumer.

2. A new probiotic antimicrobial alternative for ruminants. The complex gastrointestinal system of cattle is filled with a diverse population of microbes. Some of these contribute to digestion of feedstuffs consumed by the animal, but other microbes can cause illness or reduce feed conversion efficiency. Some microbes cause increased methane production which can causes the animal to lose as much as 12% of the energy in the feed they consume as methane which is released to the environment. ARS scientists at College Station, Texas, collaborating with scientists at Texas A&M University, isolated a never-before described bacterium from the rumen of a cow and found that when grown with certain feedstuffs, the bacterium reduced methane production while concurrently reducing numbers of undesired pathogenic bacteria such as Escherichia coli and Campylobacter in the rumen environment. The work established that this bacterium can degrade nitrate and nitrite which are toxic chemicals that often accumulate to high levels in heat- or drought-stressed forages which, when fed to cattle, can cause illness or even death. The results from this research ultimately may provide ranchers a new tool to more efficiently produce meat and milk at less cost for the American consumer and with less impact on the environment.

U.S. DEPARTMENT OF AGRICULTURE

Food and Feed Safety Research: College Station, TX