Salmonella can infect swine at any stage of their growth, from newborns to finishing pigs, where it causes diarrhoea. This accelerates transmission in farms, and can ultimately lead to Salmonella entering the human food chain and causing food poisoning. Using antibiotics to treat Salmonella in pigs is becoming problematic, largely due to the overuse of antibiotics in the pig industry and regulatory incentives to reduce antibiotics in the food chain. Antibiotic resistant Salmonella strains have been the cause of many recent outbreaks on farms, and in pork products. To reduce the spread of antibiotic resistance antibiotic use within the pig industry needs to be curtailed.

Bacteriophages are a promising alternative to treat Salmonella infections and preliminary work by several groups has suggested they would be effective at various intervention points. The aim of our research was to isolate a panel of bacteriophages that could be developed therapeutically to treat UK pigs. To date 24 different bacteriophages have been isolated from pig faecal, boar faecal, and slurry samples collected from farms across England. The morphology of the phages was identified by transmission electron microscopy; 23 phages are myovirus and one phage is a podovirus. Host range analysis was conducted and all 24 phages were able to infect all 72 multi-antibiotic resistant Salmonella isolates, which included representatives from the most common serotypes infecting pigs.

The phages have been sequenced and we will show insights from their genome content and architecture. In addition killing assays are being undertaken on different Salmonella serotypes to identify which phage, or phage combinations, show the most promise from a therapeutic standpoint. We (Leicester and AHDB Pork) will continue to collaborate with farmers and end users in order to determine, the optimum formulation, delivery and intervention points for phages to be given to swine.