Full-scale industrial phage trial targeting Salmonella on pork carcasses

Phages have been suggested as promising biocontrol agents in food, but trials demonstrating the efficiency of phage treatment under industrial settings are missing. Here we performed a full-scale industrial trial to evaluate the efficacy of a commercial phage product to reduce the prevalence of naturally occurring Salmonella on pork carcasses. A total of 134 carcasses from potentially Salmonella positive finisher herds were chosen to be tested at the slaughterhouse based on the level of antibodies in the blood. During five consecutive runs, carcasses were directed into a cabin spraying phages, resulting in a dosage of approximately 2 × 10⁷ phages per cm² carcass surface. To evaluate the presence of Salmonella, a predefined area of one half of the carcass was swabbed before phage application and the other half 15 min after. A total of 268 samples were analysed by Real-Time PCR. Under these optimized test conditions, 14 carcasses were found positive before phage application, while only 3 carcasses were positive after. This work shows that phage application allows to achieve approximatively 79% reduction of Salmonella-positive carcasses and demonstrates that implementation of phage application in industrial settings can be used as an additional strategy to control foodborne pathogens.