Abstract
The intake of high doses of viable bacteria called probiotics is a common alternative in the prevention or reduction of gastrointestinal disorders. However, the safety of probiotics has so far not been thoroughly ascertained. For this purpose, gut colonization, translocation and bacterial contamination of Peyer's patches, heart blood, lungs, liver, kidneys and spleen were assessed in C3H conventional mice 2, 4 and 6 h post-intake of either water, Bifidobacterium bre v e C50 cells or cell-free whey. An analysis of variance (ANOVA) was performed by MANOVA and ANCOVA. Bifidobacterium bre v e C50 cells were never found in the intestine or in the internal organs. Lactobacilli numbers were increased in the caecum and colon, while Bacteroides fragilis group counts showed a decrease in the colon. A similar modification to caecal and colonic floras was demonstrated following cell-free whey intake, except in the case of the colonic Lactobacilli where no increase was observed. Translocation commonly occured in all mouse groups. The most common bacteria contaminating Peyer's patches were lactobacilli. It is likely that they were of median and distal ileal origin ( p =0.0001). ANOVA also suggested that lactobacilli from the distal ileum translocated to the liver ( p =0.0001) and from the liver to the lungs ( p =0.0027), according to the product the animals ingested. In conclusion, B. bre v e C50 cells that are unable to colonize the gut did not significantly increase the translocation of the indigenous ileal flora. However, their intake modified the flora in the lower part of the digestive tract to a greater extent than the cell-free whey.