Longitudinal assessment of prevalence and incidence of Salmonella and Escherichia coli O157 resistance to antimicrobials in feedlot cattle sourced and finished in different regions of the U.S.

Authors: DORNBACH, COLTON - Texas Tech University; HALES, KRISTIN - Texas Tech University; GUBBELS, ERIN - South Dakota State University; Wells, James - Jim; HOFFMAN, ASHLEY - Texas Tech University; HANRATTY, ASHLEE - Texas Tech University; LINE, DALTON - Texas Tech University; SMOCK, TAYLOR - Texas Tech University; MANAHAN, JEFF - Texas Tech University; MCDANIEL, ZACH - Texas Tech University; KOHL, KESLEY - Texas Tech University; Sanchez, Nicole; Carroll, Jeffery - Jeff Carroll; WARREN, RUSCHE - South Dakota State University; SMITH, ZACHARY - South Dakota State University; Broadway, Paul

Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2023
Publication Date: 8/4/2023
Citation: Dornbach, C.W., Hales, K.E., Gubbels, E., Wells, J., Hoffman, A.A., Hanratty, A.N., Line, D.J., Smock, T.M., Manahan, J.L., McDaniel, Z.S., Kohl, K.B., Sanchez, N.C., Carroll, J.A., Warren, R., Smith, Z.K., Broadway, P.R. 2023. Longitudinal assessment of prevalence and incidence of Salmonella and Escherichia coli O157 resistance to antimicrobials in feedlot cattle sourced and finished in different regions of the U.S. Foodborne Pathogens and Disease. 20(8). https://doi.org/10.1089/fpd.2023.0009.
DOI: https://doi.org/10.1089/fpd.2023.0009

Interpretive Summary: Salmonella is a concern for animal health, well-being, and food safety. The entire industry is seeking strategies to reduce the impact of this bacteria in beef. Therefore, a group of scientists from the Livestock Issues Research Unit in Lubbock, TX in conjunction with scientists from South Dakota State University and Texas Tech University conducted a research project to understand how transporting cattle born and finished in different regions of the U.S. impacted Salmonella in beef cattle. Results from this study indicated within 14 days of transport to a new location, Salmonella concentrations could be drastically altered based on their environment and region within the U.S. Salmonella in lymph nodes at harvest was not found in the northern region, regardless of the origin of the cattle. These results are important for producers, animal health professionals, and consumers as they make management decisions across the U.S.

Technical Abstract: The objective was to investigate the influence of cattle origin and region of finishing on the prevalence of Salmonella, Escherichia coli O157:H7, and select antimicrobial resistance in E. coli populations. Yearling heifers (n = 190) were utilized in a 2 × 2 factorial arrangement. After determining fecal Salmonella prevalence, heifers were sorted into 1 of 4 treatments: heifers originating from SD and finished in SD (SD-SD); heifers originating from SD and finished in TX (SD-TX); heifers originating from TX and finished in SD (TX-SD); heifers originating from TX and finished in TX (TX-TX). Fecal, pen, and water scum line (WSL) samples were collected longitudinally throughout the study; hide and subiliac lymph node (SLN) samples were collected at study end. A treatment × time interaction was observed (P = 0.01) for fecal Salmonella prevalence, with prevalence being greatest for TX-TX and TX-SD heifers before transport. From d 14 through study end, prevalence was greatest for TX-TX and SD-TX heifers compared with SD-SD and TX-SD heifers. Salmonella prevalence on hides were greater (P = 0.01) for heifers finished in TX compared with SD. Salmonella prevalence in SLN tended (P = 0.06) to be greater in TX-TX and SD-TX heifers compared with TX-SD and SD-SD. Fecal E. coli O157:H7 prevalence had a treatment × time interaction (P = 0.04), with SD-TX prevalence being greater than TX-SD on d 56 and SD-SD and TX-TX being intermediate. A treatment × time interaction was observed for fecal trimethoprim-sulfamethoxazole-resistant and cefotaxime-resistant E. coli O157:H7 prevalence (P = 0.01). Overall, these data suggest region of finishing influences pathogenic bacterial shedding patterns, with the initial 14 d after feedlot arrival being critical for pathogen carriage.