Effects of the Human Intestinal Flora on Germ‐free Mice

Abstract

The effects of complete human intestinal flora and of intestinal anaerobes on germ‐free mice were studied. The gross composition of the flora of mice was similar to that of the flora with which the animals had been contaminated and appeared to be stable provided that the animals were kept isolated. The complete flora and the anaerobes reduced caecal weight to normal values and induced an antagonistic effect against Escherichia coli. In contrast to the complete flora, the anaerobes were not invasive in immunosuppressed mice and induced colonization resistance and antagonism against Pseudomonas aeruginosa.