Contamination of meat products with food-borne pathogens usually results from the carcass coming in
contact with the feces of an infected animal during processing. In the case of Salmonella, pigs can become
colonized with the organism during transport and lairage from contaminated trailers and holding pens,
resulting in increased pathogen shedding just prior to processing. Increased shedding, in turn, amplifies the
likelihood of carcass contamination by magnifying the amount of bacteria that enters the processing facility.
We conducted a series of experiments to test whether phage therapy could limit Salmonella infections at this
crucial period. In a preliminary experiment done with small pigs (3 to 4 weeks old; 30 to 40 lb), administration
of an anti-Salmonella phage cocktail at the time of inoculation with Salmonella enterica serovar Typhimurium
reduced Salmonella colonization by 99.0 to 99.9% (2- to 3-log reduction) in the tonsils, ileum, and cecum. To test
the efficacy of phage therapy in a production-like setting, we inoculated four market-weight pigs (in three
replicates) with Salmonella enterica serovar Typhimurium and allowed the challenged pigs to contaminate a
holding pen for 48 h. Sixteen naïve pigs were randomly split into two groups which received either the
anti-Salmonella phage cocktail or a mock treatment. Both groups of pigs were comingled with the challenged
pigs in the contaminated pen. Treatment with the anti-Salmonella phage cocktail significantly reduced cecal
Salmonella concentrations (95%; P < 0.05) while also reducing (numerically) ileal Salmonella concentrations
(90%; P 0.06). Additional in vitro studies showed that the phage cocktail was also lytic against several
non-Typhimurium serovars