Salmonella pig phage study

Non-typhoidal 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 or remove bacteria from the animals before they are slaughtered. Our study aimed to determine if adding a two-phage cocktail to feed can reduce Salmonella colonisation in piglets. This required spray drying phages to minimise adding additional moisture to feed and phages were spray dried in indifferent excipients to establish maximum recovery. Laboratory phage yields were not maintained during scale up in commercial spray dryers. Pleasingly, spray dried phages survived mixing and pelleting with feed in a commercial feed mill, and sustained no significant loss in phage titre when stored at barn conditions over six months. Salmonella-challenged piglets that were prophylactically fed the phage-feed diet, had significantly reduced Salmonella colonisation in different gut compartments. 16S amplicon sequencing of faecal and gut samples showed phage treatment did not negatively impact microbial communities in comparison to the healthy control piglets. Our study shows delivering dried phages via feed is effective at reducing Salmonella colonisation in pigs.