Engineering a Hyper-Adherent E. coli Nissle Probiotic Strain That Reduces Intestinal Carriage of Salmonella Pathogens in Poultry

Poultry meat and eggs are major sources of Salmonella foodborne illness, due to carriage of these bacterial pathogens in the intestinal microbiome of chickens, which is an ongoing food safety issue throughout the world. Reducing or eliminating the carriage of Salmonella in poultry would significantly improve food safety and reduce cases of human salmonellosis. This study represents a new approach to reduce or eliminate carriage of Salmonella in poultry flocks. We have created an E. coli Nissle 1917 probiotic strain that expresses a Salmonella factor with high levels of adherence. The E. coli Nissle 1917 scaffold has been used for many years as a probiotic to treat human intestinal disorders and is designated GRAS by the FDA. Our probiotic strain displays high levels of adherence to host cells, in fact, higher levels of adherence than a Salmonella strain carrying the same type 1 fimbrial genes. We demonstrate that the probiotic strain significantly outcompetes pathogenic Salmonella strains for adherence to tissue culture cells (more than 100-fold; >2 logs), and in vivo experimental challenges revealed that the probiotic strain mediates a significant exclusion (more than a 10-fold reduction; >1 log) of Salmonella from the intestines of broilers, layers, and turkeys.