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ARS Home » Plains Area » College Station, Texas » Southern Plains Agricultural Research Center » Food and Feed Safety Research » Research » Research Project #429509

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

Location: Food and Feed Safety Research

2016 Annual Report


1a. Objectives (from AD-416):
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.


1b. Approach (from AD-416):
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.


3. Progress Report:
This is a new project that replaced 3091-32000-030-00D, and which is expanding upon the work of the precursor project. Work under the new project during FY 2016 resulted in significant progress in evaluating and developing new strategies, as well as best use applications of existing strategies, for the control of foodborne pathogens and antimicrobial resistant bacteria in cattle and swine. Project work has identified critical control points for the application of new and improved intervention needs, and provided new knowledge on routes of Salmonella infection and the application of an array of novel feed additives to reduce pathogen colonization in swine and cattle. Work in FY 2016 continues ongoing efforts aimed at development of practical, cost-effective interventions, or management practices to reduce the carriage and environmental dissemination of pathogenic and antimicrobial-resistant microbes by food-producing animals. Where practical, these interventions are being designed to contribute to the efficiency and profitability of animal production. 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.


4. Accomplishments
1. Salmonella in meat trimmings from a pork processing plant. Salmonella is an important cause of foodborne illness, causing an estimated one million infections in the United States each year. Salmonella are known to be able to invade and colonize the animals' lymph nodes, thereby establishing a persistent infection in animals that subsequently are recognized as carrier animals. These animals do not exhibit symptoms of disease and thus can avoid detection during processing. ARS researchers at College Station, Texas, in collaboration with scientists from Texas A&M University and Texas Tech University, sampled lymph-containing meat trimmings at a major pork processing plant over a six month period and found that nearly 20% were positive for Salmonella, with the incidence of recovery being greater in the winter and spring compared to summer and fall. These findings highlight the potential risk of human exposure to Salmonella and identify critical control points for the implementation of intervention methods.

2. Interventions to rid Salmonella from peripheral lymph nodes of cattle. Salmonella is an important foodborne and animal pathogen that can reside within the gastrointestinal tract and invade and establish persistent infections within the animal’s lymph tissue. This evades the host's own natural anti-infection mechanisms as well as escapes targeting by commonly available antibiotic therapies. ARS researchers at College Station, Texas, working with collaborators from industry and Texas Tech University, developed dosing regimens for the application of bacteriophage and chlorate-based intervention technologies, to make them capable of reaching and killing Salmonella residing within peripheral lymph nodes of cattle. This is an important discovery that could ultimately lead to the development of efficacious anti-Salmonella interventions that reduce the carriage of Salmonella in the lymph nodes of live animals.


5. Significant Activities that Support Special Target Populations:
None.