Effects of yeast probiotic formulation on viability, revival and protection against infection with Salmonella enterica ssp enterica serovar Typhimurium in mice

Aims: To compare the effects of five yeast probiotic formulations on viability, revival and washout kinetic in the digestive tract of mice, and the protection against an experimental infection with Salmonella enterica serovar Typhimurium. Methods and Results: The number of viable cells in five commercial probiotic products codified as A, B, C and D (Saccharomyces boulardii- lyophilized) and E (Saccharomyces cerevisiae- aqueous suspension) was determined, as well as revival and washout kinetic in mouse intestine. Protective capacity was evaluated by survival rate and histopathology of liver and intestine of mice treated with each product and then challenged with Salm. Typhimurium. Conclusions: Product A contained the highest number of viable cells and, fed to mice, gave the highest counts of viable yeasts and the longest persistence in faeces. Probably as a consequence, the highest survival and protection of intestinal and hepatic tissues were observed when product A was used for mouse treatment. Product E showed low counts in the formulation and was not recovered from mouse intestine. Significance and Impact of the Study: Formulation (lyophilization or aqueous suspension) is an important factor for revival and survival of a probiotic product in vivo and consequently for its protective properties.