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Prophylactic Delivery of a Bacteriophage Cocktail in Feed Significantly Reduces Salmonella Colonization in Pigs

Thanki, Anisha M.; Mignard, Guillaume; Atterbury, Robert J.; Barrow, Paul; Millard, Andrew D.; Clokie, Martha R. J.

Prophylactic Delivery of a Bacteriophage Cocktail in Feed Significantly Reduces Salmonella Colonization in Pigs Thumbnail


Anisha M. Thanki

Guillaume Mignard

Paul Barrow

Andrew D. Millard

Martha R. J. Clokie


David T. Pride


Nontyphoidal Salmonella spp. are a leading cause of human food poisoning and can be transmitted to humans via consuming contaminated pork. To reduce Salmonella spread to the human food chain, bacteriophage (phage) therapy could be used to reduce bacteria from animals' preslaughter. We aimed to determine if adding a two-phage cocktail to feed reduces Salmonella colonization in piglets. This first required spray drying phages to allow them to be added as a powder to feed, and phages were spray dried in different excipients to establish maximum recovery. Although laboratory phage yields were not maintained during scale up in a commercial spray dryer (titers fell from 3 × 108 to 2.4 × 106 PFU/g respectively), the phage titers were high enough to progress. Spray dried phages survived mixing and pelleting in a commercial feed mill, and sustained no further loss in titer when stored at 4°C or barn conditions over 6 months. Salmonella-challenged piglets that were prophylactically fed the phage-feed diet had significantly reduced Salmonella colonization in different gut compartments (P < 0.01). 16S rRNA gene sequencing of fecal and gut samples showed phages did not negatively impact microbial communities as they were similar between healthy control piglets and those treated with phage. Our study shows delivering dried phages via feed effectively reduces Salmonella colonization in pigs. Infections caused by Salmonella spp. cause 93.8 million cases of human food poisoning worldwide, each year of which 11.7% are due to consumption of contaminated pork products. An increasing number of swine infections are caused by multidrug-resistant (MDR) Salmonella strains, many of which have entered, and continue to enter the human food chain. Antibiotics are losing their efficacy against these MDR strains, and thus antimicrobial alternatives are needed. Phages could be developed as an alternative approach, but research is required to determine the optimal method to deliver phages to pigs and to determine if phage treatment is effective at reducing Salmonella colonization in pigs. The results presented in this study address these two aspects of phage development and show that phages delivered via feed prophylactically to pigs reduces Salmonella colonization in challenged pigs.


Thanki, A. M., Mignard, G., Atterbury, R. J., Barrow, P., Millard, A. D., & Clokie, M. R. J. (2022). Prophylactic Delivery of a Bacteriophage Cocktail in Feed Significantly Reduces Salmonella Colonization in Pigs. Microbiology Spectrum, 10(3), e0042222.

Journal Article Type Article
Acceptance Date Apr 13, 2022
Online Publication Date May 17, 2022
Publication Date May 17, 2022
Deposit Date Jun 23, 2022
Publicly Available Date Jun 24, 2022
Journal Microbiology spectrum
Electronic ISSN 2165-0497
Publisher American Society for Microbiology
Peer Reviewed Peer Reviewed
Volume 10
Issue 3
Pages e0042222
Keywords Infectious Diseases; Cell Biology; Microbiology (medical); Genetics; General Immunology and Microbiology; Ecology; Physiology
Public URL
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