In vitro inhibition of expression of virulence genes responsible for colonization and systemic spread of enteric pathogens using Bifidobacterium bifidum secreted molecules

► Molecules secreted by Bifidobacterium bifidum interfere with both attachment and invasion of Salmonella and E. coli O157:H7. ► Interference was achieved by down-regulation of regulatory genes controlling the virulence factors. ► The ability of both pathogens to colonize eukaryotic cells was significantly reduced by these molecules. ► The secreted molecules diminished the ability of Salmonella to survive and multiply within macrophages.