Location: Food and Feed Safety Research
2020 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 fiscal year 2020 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 pathogen infection and dissemination (Objective 3), as well elucidating mechanisms of antimicrobial resistance acquisition and dissemination (Objective 4). Project work continued ongoing efforts aimed at the development of practical, cost-effective interventions, including antibiotic alternatives 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. Delayed access of carcass-degrading bacterial and insect populations impacts carcass decomposition. Large scale mortality events resulting from adverse weather conditions or disease can saturate an agricultural site with decomposing carcasses. We lack an understanding of such events and how they disrupt the normal behavior of carcass-feeding insects and their subsequent impact on the local insect and microbial ecosystems. ARS researchers at College Station, Texas, in collaboration with scientists from Texas A&M University, investigated the insects and microbes present on the carcasses and in the soil when insects gained immediate or delayed access to carcasses. The work established that delaying access markedly affected bacterial decomposing capability, insect activity, and the ability of these interkingdom-degraders to interact on the decomposing carcasses, but not in the surrounding soil. These results provide important information to help producers effectively dispose of carcasses during large scale die-off events to reduce risks of vector-borne spread, and facilitate farm management of food poisoning pathogens such as Salmonella, Campylobacter, and enterohemorrhagic Escherichia coli.
2. New antimicrobial use of a well-known, highly regarded, and safe anti-inflammatory compound. Bacteria that cause disease (pathogens) in food-producing animals and humans have raised concerns among public health officials because diseases once believed to be largely eradicated are reappearing. Moreover, the emergence of antibiotic resistant bacteria in animal agriculture has raised concerns that infections caused by pathogenic bacteria will be more difficult to treat. ARS researchers at College Station, Texas, established the potential of a non antibiotic compound, commonly used as an anti-inflammatory agent, to inhibit the growth of multidrug resistant Escherichia coli and Salmonella isolated from cattle. Results demonstrated that the novel antimicrobial use of this anti-inflammatory compound, called methylsulfonylmethane (MSM), significantly inhibited the growth of the multidrug resistant bacteria even at low doses. MSM antibacterial activity may prove useful during pre or postharvest food safety as a disinfectant. These results provide livestock producers and food processors with a valuable nonantibiotic alternative that has an established record of good clinical safety.
Review Publications
Poole, T.L., Benjamin, R., Genovese, K.J., Nisbet, D.J. 2019. Methylsulfonylmethane exhibits bacteriostatic inhibition of Escherichia coli, and Salmonella enterica Kinshasa, in vitro. Journal of Applied Microbiology. 127(6):1677-1685. https://doi.org/10.1111/jam.14446.
Brown, T.R., Edrington, T.S., Genovese, K.J., He, L.H., Anderson, R.C., Nisbet, D.J. 2019. Evaluation of the efficacy of three direct fed microbial cocktails to reduce fecal shedding of Escherichia coli O157:H7 in naturally colonized cattle and fecal shedding and peripheral lymph node carriage of Salmonella in experimentally infected cattle. Journal of Food Protection. 83(1):28-36. https://doi.org/10.4315/0362-028X.JFP-19-208.
Levent, G., Schlochtermeier, A., Ives, S.E., Norman, K.N., Lawhon, S.D., Loneragan, G.H., Anderson, R.C., Vinasco, J., Scott, H.M. 2019. Population dynamics of Salmonella enterica within beef cattle cohorts followed from single-dose metaphylactic antibiotic treatment until slaughter. Applied and Environmental Microbiology. 85(23):e01386-19. https://doi.org/10.1128/AEM.01386-19.
Cagle, C.M., Batista, L.D., Anderson, R.C., Fonseca, M.A., Cravey, M.D., Julien, C., Tedeschi, L.O. 2019. Evaluation of different inclusion levels of dry live yeast impacts on various rumen parameters and in situ digestibilities of dry matter and neutral detergent fiber in growing and finishing beef cattle. Journal of Animal Science. 97(12):4987-4998. https://doi.org/10.1093/jas/skz342.
Beier, R.C., Harvey, R.B., Hernandez Jr., C.A., Andrews, K., Droleskey, R.E., Hume, M.E., Davidson, M.K., Bodeis-Jones, S., Young, S., Anderson, R.C., Nisbet, D.J. 2019. Disinfectant and antimicrobial susceptibility profiles of Campylobacter coli isolated in 1998 to 1999 and 2015 from swine and commercial pork chops. Journal of Food Science. 84(6):1501-1512. https://doi.org/10.1111/1750-3841.14622.
Božic, A., Anderson, R.C., Crippen, T.L., Swaggerty, C.L., Hume, M.E., Beier, R.C., He, L.H., Genovese, K.J., Poole, T.L., Harvey, R.B., Nisbet, D.J. 2020. Inhibition of Salmonella binding to porcine intestinal cells by a wood-derived prebiotic. Microorganisms. 8(7):1051. https://doi.org/10.3390/microorganisms8071051.
