Location: Meat Safety and Quality2021 Annual Report
Objective 1: Determine ecological and environmental factors associated with the levels and persistence of pathogens and antibiotic resistance in the host animal and transmission in the livestock production environment. Sub-objective 1.A: Determining sources and transmission of pathogens and antibiotic resistance in preharvest beef production environments. Sub-objective 1.B: Determining the development of AMR in commensal and pathogenic bacteria and their transmission in feedlot cattle and production systems. Sub-objective 1.C: Determining the impact of intestinal microbiome development on the longitudinal colonization and shedding of foodborne pathogens and antibiotic resistance in swine. Objective 2: Develop and evaluate intervention strategies that reduce or eliminate the occurrence, transmission, or persistence of foodborne pathogens in cattle, swine, their production systems, and the environment. Sub-objective 2.A: Evaluating the potential for dietary supplements to reduce pathogen and antibiotic resistance shedding in beef cattle feces and into the environment. Sub-objective 2.B: Identification of alternatives to antibiotics for use in nursery swine to reduce pathogens and AMR bacteria.
The overall goal of this project is to reduce the risk of foodborne illness, by providing information that can be used to reduce transmission of zoonotic pathogens and antibiotic resistance from cattle and swine production to food, water, and the environment. Cattle and swine remain important reservoirs for foodborne pathogen and antibiotic resistance, increasing the potential for transmission of foodborne pathogens to humans. Primary targets of the work include Escherichia coli O157:H7 and other Shiga-toxigenic E. coli, Salmonella, Campylobacter, and antibiotic resistant bacteria. Specific objectives are to (1) Determine ecological and environmental factors associated with the levels and persistence of pathogens and antibiotic resistance in the host animal and transmission in livestock production environments; and (2) Develop and evaluate intervention strategies that reduce or eliminate the occurrence, transmission, or persistence of foodborne pathogens in cattle, swine, their production systems, and the environment. Understanding the potential sources and transmission dynamics of pathogens in production environments is critical for identifying strategies to reduce their introduction and dissemination. Systems approaches examining multiple pathways and sample types will be used to identify the most important sources and transmission routes of pathogens and antibiotic resistance, using the U.S. Meat Animal Research Center (USMARC) preharvest beef and swine production environments. Moreover, research will determine how antibiotic use in cattle and swine affects pathogens and the development of antibiotic resistance in animals and their production environment. Research will also be conducted to identify alternatives to antibiotic use in cattle and swine. Expected outcomes are scientific information and management strategies that can be used to reduce foodborne pathogens and antibiotic resistance in livestock production, thus contributing to a safer food and water supply and a lower risk of human foodborne illness. These outcomes will benefit U.S. agriculture and numerous stakeholders, including livestock producers, animal harvest and meat processing industries, regulatory agencies, and consumers.
This project replaced 3040-32000-032 in Fiscal Year (FY) 2021. Additional work and accomplishments have been stated in the final report for 3040-32000-032-00D. Understanding the impact of antibiotic use in swine and cattle production is important to determining the potential for the development of antibiotic resistance in commensal and pathogenic bacteria (Objectives 1 and 2). Under Sub-objective 1A, a long-term study was continued from the previous project, to identify factors that affect the occurrence and transmission dynamics of multiple pathogens and antibiotic resistance in cattle and waterways in pasture-based cattle production. Factors under study include wildlife, migratory waterfowl, and other environmental and seasonal effectors. Water, sediment, and feces were collected and analyzed, and weather and camera data were recorded. Under Sub-objective 1B, research with high-risk cattle was initiated with collaborators at Texas Tech University (TTU) and University of Nebraska-Lincoln to study how metaphylactic use of antibiotics might impact pathogens and antimicrobial-resistant (AMR) bacteria. Nearly 260 steers were purchased from sale barns in New Mexico and Missouri for this study being conducted at the TTU Burnett Center. Animals were treated with saline, or one of three antibiotics commonly used for metaphylactic treatment in feedlot cattle. Fecal samples were collected on six occasions from arrival until harvest from each animal. Each fecal sample was assayed for AMR Escherichia coli and Salmonella, and when present, isolates were collected and characterized for antibiotic susceptibility. For Sub-objective 2A, the environment was evaluated using samples of feed and of the feedlot surface material collected prior to and for 56 days after animals were placed into the pens. Antibiotic treatment appeared to impact the onset of bovine respiratory disease and the shedding of Salmonella and AMR Escherichia coli in the feces. Follow-up work will also determine if horizontal gene transfer occurs between multidrug resistant Escherichia coli and Salmonella within these cattle and the feedlot environment. Reducing pathogen and AMR bacteria persistence and transmission from cattle and swine will require the development of intervention strategies that reduce their prevalence in the animal, the manure, and the production environment (Objective 2). Under Sub-objective 2A, a study was initiated to determine the impact of dietary antimicrobials on fecal shedding of AMR Escherichia coli and Enterococcus spp. Fecal and environmental samples were collected prior to and after the supplementation of dietary antimicrobials. Under Sub-objective 2B, research with a potential fungal probiotic was conducted at Clay Center, Nebraska in collaboration with scientists from Beltsville, Maryland. Piglets were orally treated with saline or the probiotic fungi on days 10 and 24 of age. Fecal samples were collected at weaning and at the end of the nursery phase to determine pathogen and AMR presence. Interestingly, AMR bacteria were observed at high levels in piglets regardless of age and the cecum appears to be a reservoir for AMR in the young piglet. Additional research was conducted to determine transcriptomics of milk in nursing sows, and numerous genes associated with pathogen recognition and immune response were observed to be differentially expressed in sows of different age and milk type. Subsequent efforts will identify milk oligosaccharides and determine relationships with pathogen colonization and shedding in piglets.
Clemmons, B.A., Schneider, L.G., Melchior, E.A., Lindholm-Perry, A.K., Hales, K.E., Wells, J., Freetly, H.C., Hansen, S.L., Drewnowski, M.E., Hartman, S.J., Myer, P.R. 2021. The effects of feeding ferric citrate on ruminal bacteria, methanogenic archaea, and methane production in growing beef steers. Access Microbiology. 3(1). Article 000180. https://doi.org/10.1099/acmi.0.000180.