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Veterinary Diagnostic and Production Animal Medicine

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Published Version

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Foodborne Pathogens and Disease





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Salmonella is a foodborne pathogenic bacterium that causes human illnesses and morbidity and mortality in swine. Bacteriophages are viruses that prey on bacteria and are naturally found in many microbial environments, including the gut of food animals, and have been suggested as a potential intervention strategy to reduce Salmonella levels in the live animal. The present study was designed to determine if anti-Salmonella phages isolated from the feces of commercial finishing swine could reduce gastrointestinal populations of the foodborne pathogen Salmonella Typhimurium in artificially inoculated swine. Weaned pigs (n = 48) were randomly assigned to two treatment groups (control or phage-treated). Each pig was inoculated with Salmonella Typhimurium (2 × 1010 colony forming units/pig) via oral gavage at 0 h and fecal samples were collected every 24 h. Swine were inoculated with a phage cocktail via oral gavage (3 × 109 plaque forming units) at 24 and 48 h. Pigs were humanely killed at 96 h, and cecal and rectal intestinal contents were collected for quantitative and qualitative analysis. Fecal Salmonella populations in phage-treated pigs were lower (p < 0.09) than controls after 48 h. Phage treatment reduced intestinal populations of inoculated Salmonella Typhimurium in pigs compared to controls at necropsy. Cecal populations were reduced (p = 0.07) by phage treatment >1.4 log10 colony forming units/g digesta, and rectal populations were numerically reduced. The number of pigs that contained inoculated Salmonella Typhimurium was reduced by phage treatment, but a significant (p < 0.05) reduction was only observed in the rectum. We conclude that phages can be a viable tool to reduce Salmonella in swine. Further research needs to be performed to determine the most efficacious dosing regimens and the most effective combinations of phages targeting the diverse Salmonella population found in swine before they can enter the food supply.


This article is published as Callaway, Todd R., Tom S. Edrington, Andrew Brabban, Betty Kutter, Locke Karriker, Chad Stahl, Elizabeth Wagstrom, Robin Anderson, Toni L. Poole, Ken Genovese, Nathan Krueger, Roger Harvey, and David J. Nisbet. "Evaluation of phage treatment as a strategy to reduce Salmonella populations in growing swine." Foodborne Pathogens and Disease 8, no. 2 (2011): 261-266. Final publication is available from Mary Ann Liebert, Inc., publishers. DOI: 10.1089/fpd.2010.0671.


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