Recipient Organization
KANSAS STATE UNIV
(N/A)
MANHATTAN,KS 66506
Performing Department
(N/A)
Non Technical Summary
Antimicrobial resistance (AMR) is a significant public health threat, and the use of antimicrobials in food producing animals has received a great amount of scrutiny. Addressing AMR is a high priority for both animal agriculture as well as the public health since many of the medically important antimicrobials are used to treat or prevent infections in animals. Bovine respiratory disease (BRD) is a major reason for the metaphylactic use of antimicrobials in the beef industry and has major economic and animal health and welfare implications. A number of medically important antibiotics are widely used in the treatment and prevention of BRD in cattle. Therefore, BRD treatment and control are a major concern for emergence and dissemination of AMR. The goal of the proposed project is to generate data on the impact of chlortetracycline (CTC) plus macrolide antimicrobial combination on animal health and performance and to develop mitigation strategies with the goal to reduce the use of antimicrobial metaphylaxis in beef cattle. Treatment choices can drive patterns of AMR prevalence. Metaphylactic administration of in-feed chlortetracycline (CTC) and injectable macrolide are commonly used in the feedlot industry to control BRD and other infections.We seek to guide mitigation strategies toward a goal of reducing the use of antimicrobial metaphylaxis in feedlot cattle. A field study with high-risk calves in a commercial feedyard is proposed for evaluating in-feed CTC (one and two pulses) with injectable tulathromycin as metaphylaxis. Fecal, nasal, feed, and water samples will be collected from each pen of cattle on days 0, 6, 12, 28, at reimplant, and prior to closeout for analyses to determine prevalence, abundance of tetracycline and macrolide resistance genes, and antimicrobial susceptibility patterns of BRD pathogens, gut commensals and foodborne pathogens. A subset of the samples will be subjected to shotgun metagenomics analysis to identify bacterial community composition and AMR genes (resistome).We will survey feedlot managers to identify metaphylaxis practices, antimicrobial resistance perceptions, and potential knowledge gaps. Results from the field study will be incorporated into training and outreach materials for feedlot producers, nutritionists, veterinarians, stakeholders, regulatory agencies, and consumers to recommend antimicrobial use practices, antimicrobial resistance and effective mitigation strategies in feedlot cattle. The proposed study addresses the goals of the program priority area to specifically describe and quantify the risk of AMR pathogens and also to determine improved, best-management practices and approaches in antibiotic stewardship.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Goals / Objectives
Ourprimary long-term goal is to generate data to inform AMR mitigation strategies by balancing two major inputs concerning AM use for the BRD control: 1) benefits to animal health and welfare (therapeutic efficacy), and 2) concerns for development and dissemination of AMR bacteria and AMR genes in the animal-and its environment (AMR impact). Our study is designed to inform AMR mitigation strategies related to the use of macrolides (injectable) and tetracyclines (in-feed) in beef cattle for the control of BRD by describing and quantifying the impact on health, performance, and AMR development. Each objective is able to be completed independently, but we anticipate outcomes from each objective to be synergistic. The specific objectives of the proposed study are:Objective 1: Conduct a survey of feedlot managers and feedlot veterinary consultants to document antimicrobial use and to determine perceptions related to antimicrobial use practices, antimicrobial resistance, and the relationship of antimicrobial use practices to health of cattle and of the consumer.Objective 2: Evaluate metaphylactic use of injectable (tulathromycin) and in-feed antibiotics (pulse feeding of CTC) for the control of BRD in feedlot cattle to generate field-derived data on the efficacy, cattle performance, and AMR development (culture-based assessment of respiratory and foodborne pathogens, and metagenomics analyses) in cattle (nasal swabs and feces samples) and cattle production environment (feed and water).Objective 3: Disseminate information on the use of antimicrobials in feedlot cattle, and our research findings on AMR and its impact on gut commensal bacteria.
Project Methods
Objective 1Survey of feedyard managers and veterinary consultants to evaluate antimicrobial use practices and antimicrobial resistance perceptions:A quantitative survey will be carried out to ask feedyard managers and veterinary consultants on the antimicrobial use practices, including injectable metaphylaxis and of the use and frequency of pulse feeding of CTC in feedyards. Survey will be created, distributed, and evaluated in Year 1 of the proposal.Data will be summarized by descriptive statistics and visualized by charts/plots. Depending on the discreteness of survey responses, linear or generalized linear model will be used to characterize the distribution of AMR perceptions and identify factors associated with the distribution. Statistical analyses will be performed using SAS TABULATE, SGPLOT, SGPANNEL, MIXED, GENMOD and/or LOGISTIC procedures.Objective 2We are proposing to test injectable Tulathromycin and in-feed CTC based on the available antimicrobial use data. However, if the survey results show different use data with respect to in-feed CTC (number of pulses), then we will redesign the study based on the survey data.Animals and study design: A randomized block design (2,400 cattle; 8 pens with 75 animals per pen; four treatment groups) will be utilized to evaluate health, performance, and AMR impact of cohort-level metaphylactic administrations of combinations of injectable tulathromycin and one or two pulse feedings of CTC. Calves will be housed in pens upon arrival to the feedlot and provided ad libitum access to grass hay and water and will be transitioned to high-concentrate ration consistent with current US feeding practices.Treatment groups: Calves will be randomly assigned to 1 of 4 treatment groups. All 4 pens within a block will be housed adjacent to each other, and all 32 pens will be housed in the same section of the feedlot.The four treatment groups are: No antibiotic (NEGATIVE CONTROL), Injectable tulathromycin (Draxxin, Zoetis Animal Health): 2.5 mg/kg bodyweight (BW) injected subcutaneously (TUL), Injectable tulathromycin plus one pulse dose of CTC (Aureomycin, Zoetis Animal Health): CTC administered in the feed at 22 mg/kg of BW on days 1-5 (CTC-1) and Injectable tulathromycin plus two pulse doses of CTC: administered in the feed at 22 mg/kg of BW on days 1-5 and 7-11 (CTC-2).Calves will be evaluated for clinical signs of BRD daily by pen riders blinded to treatment groups. Any animal that appears sick or morbid will be brought to the hospital for further evaluation. All animal health and performance outcomes will be captured through feedyard computer system.Nasal secretions, fecal, feed, and water collections: Nasal swabs and fecal samples from a subset of 25 randomly selected animals will be collected chute-side during the processing and treatment allocation of calves on day 0 (before antibiotic administration), subsequently on days 6, 12, 28, at re-implant, and just prior to closeout. Nasal swab samples will be collected using commercially available deep, double guarded culture swabs (Butler Schein sterile Dacron guarded swabs, Fisher Scientific Co., Hanover Park, IL). On the same day, feed and water samples will be collected.Bacterial isolations and identifications from nasal and fecal samples: From the nasal swab samples, the isolation of Pasteurella spp. will be carried out as per the procedure outlined in De Rosa et al.and M. haemolytica will be carried out as per Zaheer et al. Two isolates of each pathogen exhibiting typical colony morphology will be subjected to catalase and oxidase biochemical tests. Genus and species confirmation of P. multocida and M. haemolytica will be by PCR as per Deressa et al. Escherichia coli, Enterococcus spp., Salmonella and Campylobacter isolations and identifications from fecal samples will be performed as per our published procedures.Antimicrobial susceptibility determinations: Minimum inhibitory concentrations (MIC) will be determined by broth-microdilution method as per CLSI guidelines (2018).DNA extraction from nasal, fecal, feed, and water samples: Total DNA will be extracted using the "PowerSoil® DNA isolation kit" (MO BIO Laboratories; Carlsbad, CA). The isolated DNA will be stored at -20°C until used for quantification of tetracycline and macrolide resistance genes and metagenome shotgun sequencing.Quantification of macrolide-and tetracycline resistance genes: For quantification, we will target the most common tetracycline [tet(A), tet(B), tet(C), tet(K), tet(L), tet(M), and tet(O)] and macrolide [erm(A), erm(B), and erm(C)] resistance genes in fecal DNA by real-time quantitative PCR methods144,145.Statistical Analysis: Statistical analysis will be performed under the generalized linear model using SAS (v9.4 or higher; Cary, NC) GLIMMIX, MIXED, GENMOD and/or LOGISTC procedures. Comparison between two treatment groups will be carried out by testing for non-zero difference at the 0.05 level. Shotgun metagenomics of nasal, fecal, feed, and water samples: Shotgun metagenomics will be performed on pen-pooled samples.Sequence read processing and analysis: We will perform both gene-centric and genome-centric analyses on the shotgun metagenomes to ensure we capture information on both the community level changes as well as identifying specific bacterial populations that are impacted by antimicrobials.Gene-centric and Genome-centric analyses - Bioinformatics analysis of culture independent shotgun metagenomics sequence data will be performed on CFSAN's Galaxy bioinformatics instance GalaxyTrakr (https://galaxytrakr.org). We will assemble metagenomes, bin them into genomes and analyze for functional genes and pathways. We will assess the impact of antimicrobials on these genomes, with more emphasis on AMR gene functions.Objective 3Our education and outreach components are designed to inform stake holders, including policy makers, producers, scientists, pharmaceutical and health industry partners, and consumers on issues concerning AMR development and spread, and mitigation strategies.Feedyard manager and producer conferenceCommunication of results at the key state and national beef cattle meetingsScientific and lay publicationsEstablishing searchable database for gut metagenomesTraining next generation of scientists and educatorsA series of fact sheets will be developed on antimicrobial use and BRD in collaboration with Dr. Allen to help beef cattle producers understand where they may have the most economical benefit and where their use may increase AMR.