Oral Administration of a Select Mixture of Lactobacillus and Bacillus Alleviates Inflammation and Maintains Mucosal Barrier Integrity in the Ileum of Pigs Challenged with Salmonella Infantis

Salmonella is important as both a cause of clinical disease in swine and as a source of food-borne transmission of disease to humans. Lactobacillus and Bacillus are often used as antibiotic substitutes to prevent Salmonella infection. In this study, we evaluated the effects of a select mixture of Lactobacillus johnsonii L531, Bacillus licheniformis BL1721 and Bacillus subtilis BS1715 (LBB-mix) in prevention of Salmonella enterica serovar Infantis infection in a pig model. LBB-mix was orally administered to newly weaned piglets for seven days before S. Infantis challenge. LBB-mix pretreatment ameliorated S. Infantis-induced fever, leukocytosis, growth performance loss, and ileal inflammation. Pre-administration of LBB-mix reduced the number of Salmonella in the feces but increased the number of goblet cells in the ileum. S. Infantis infection resulted in an increase in cell death in the ileum, this increase was attenuated by LBB-mix consumption. Claudin 1 and cleaved caspase-1 expression was decreased in the ileum of pigs challenged with S. Infantis, but not in pigs pretreated with LBB-mix. In conclusion, our data indicate that a select LBB-mix has positive effects on controlling S. Infantis infection via alleviating inflammation and maintaining the intestinal mucosal barrier integrity in pigs.