Adhesion and competitive inhibition and displacement of human enteropathogens by selected lactobacilli

Competition with pathogens for adhesion and colonization of the mucosal surfaces are possible protective mechanisms of probiotics. Here, we assessed the adhesive properties and the ability to inhibit the adhesion and to displace pathogens of three selected Lactobacillus strains using Caco-2 cells and a human intestinal mucus model. The adhesion levels showed a great variability, ranging between 1% and 9.7% in the mucus model and between 7.7 and 61.1 bacterial cells/microscopy view in the Caco-2 model. A good correlation between both models was observed. The ability to inhibit the adhesion or to displace adhered pathogens was variable depending on both the lactobacilli and the pathogen tested. The inhibition and displacement profiles were very different suggesting that different mechanisms are implied in both processes. A very high specificity in the inhibition of the adhesion and displacement of enteropathogens by lactobacilli was observed indicating the need for a case-by-case assessment in order to select strains with the ability to inhibit or displace a specific pathogen.