#09-131

Complete

Date Full Report Received

11/04/2010

Date Abstract Report Received

11/04/2010

Investigation

Institution:
Primary Investigator:

Bacteriophages are naturally occurring microorganisms that target and destroy bacteria. Our laboratory previously demonstrated that administering bacteriophages to pigs reduces Salmonella colonization when those pigs are exposed to a contaminated environment. These results indicated that bacteriophages could be useful in controlling increases in Salmonella shedding that occur just prior to processing due to transportation and lairage. The purpose of the current project was to increase the efficacy of our phage treatment by: 1) increasing the host-range to include other common Salmonella serovars associated with swine; 2) developing a more affordable microencapsulation process to protect the phages from stomach acids; and 3) making deliver more practical by determining whether phages can be direct fed. We collected samples from wastewater treatment facilities and isolated 20 distinct phages belonging to either the Siphoviridae or Myoviridae families. From this library we identified 10 phages that together lysed a mixed culture of Salmonella enterica Typhimurium, Enteriditis, and Kentucky. Phages were microencapsulated using two methods that had minimal effect on phage viability. Microencapsulated phages remained stable at various temperatures for up to 14 days with no appreciable drop in viability. Twenty-one pigs in three replicates were randomly placed into three groups: feed (F), gavage (G), and control (G). The F group was direct fed the phage cocktail daily for five days. On the fifth day, the G group received the same phage cocktail by gavage, while C pigs received a mock treatment with no phage. All pigs were then challenged with Salmonella enterica Typhimurium. Pigs in the F group were significantly less likely to shed Salmonella post-challenge compared to pigs in both the G and C groups. Likewise, the concentrations of Salmonella in the ileal and cecal samples were significantly lower than ileal and cecal samples from C pigs. Taken together, these results indicate that direct feeding phages is a practical and effective means of reducing Salmonella colonization and shedding in pigs.