No Beneficial Effects Evident for Enterococcus faecium NCIMB 10415 in Weaned Pigs Infected with Salmonella enterica Serovar Typhimurium DT104

Salmonella enterica serovar Typhimurium DT 104 is the major pathogen for salmonellosis outbreaks in Europe. We tested if the probiotic bacteriumEnterococcus faecium NCIMB 10415 can prevent or alleviate salmonellosis. Therefore, piglets of the German Landrace breed that were treated withE. faecium (n = 16) as a feed additive and untreated controls (n = 16) were challenged withS. Typhimurium 10 days after weaning. The presence of salmonellae in feces and selected organs, as well as the immune response, were investigated. Piglets treated withE. faecium gained less weight than control piglets (P = 0.05). The feeding ofE. faecium had no effect on the fecal shedding of salmonellae and resulted in a higher abundance of the pathogen in tonsils of all challenged animals. The specific (anti-Salmonella IgG) and nonspecific (haptoglobin) humoral immune responses as well as the cellular immune response (T helper cells, cytotoxic T cells, regulatory T cells, γδ T cells, and B cells) in the lymph nodes, Peyer's patches of different segments of the intestine (jejunal and ileocecal), the ileal papilla, and in the blood were affected in the course of time after infection (P < 0.05) but not by theE. faecium treatment. These results led to the conclusion thatE. faecium may not have beneficial effects on the performance of weaned piglets in the case ofS. Typhimurium infection. Therefore, we suggest a critical discussion and reconsideration ofE. faecium NCIMB 10415 administration as a probiotic for pigs.