[Elimination from the digestive tract of a "gnotoxenic" child of a "Lactobacillus casei" strain, isolated from a commercial preparation: antagonistic effect of an "Escherichia coli" strain of human origin, demonstrated in "gnotoxenic" mice (author's transl)].

A strain of Lactobacillus casei from a pharmaceutical preparation became established in the digestive tract of an axenic child. It was eliminated by the first bacteria occurring after inoculation of the child's digestive tract with a human flora, before the child was taken out of the isolator. Using "gnotoxenic" mice, we found that the elimination of L. casei was due to a bactericidal effect of the Escherichia coli of human origin, within the digestive tract.