In vitro evaluation of Lactobacillus gasseri strains of infant origin on adhesion and aggregation of specific pathogens.

Numerous Lactobacillus species are members of the normal healthy human intestinal microbiota, and members of the Lactobacillus family predominate among the current marketed probiotic strains. Most of the current commercial probiotic strains have not been selected for specific applications but rather have been chosen based on their technological properties. Often the ability of such strains to temporarily colonize the gastrointestinal tract may be lacking, and the interactions with intestinal microbiota are few. Furthermore, the competitive exclusion properties of potential probiotic bacteria are strain specific and vary greatly. Thus, it is highly desirable that new candidate probiotic isolates originate from the healthy target population. In this study, seven newly isolated strains of Lactobacillus gasseri originating from feces of a healthy newborn child were evaluated for their ability to adhere to intestinal mucus, to autoaggregate and coaggregate with the model pathogens Cronobacter sakazakii (ATCC 29544) and Clostridium difficile (1296). All the bacterial strains, single or in combination, in viable and nonviable forms, were able to autoaggregate. The coaggregation with C. sakazakii or C. difficile was higher (P < 0.05) in nonviable than in the viable forms. Single L. gasseri strains showed similar adhesion abilities to intestinal colon mucus. The seven L. gasseri strains when combined were also able to significantly compete with, displace, and inhibit the adhesion of C. sakazakii and C. difficile in the mucus model. This study demonstrates that the studied L. gasseri strains fulfill the basic adhesion and aggregation properties for probiotics and could be considered for potential future use in children.