Inhibition of polyposis in the small intestine of BALB/c mice by intestinal bacteria.

The incidence of polyposis and the number of polyps per mouse were significantly lower in conventionalized (CVz) mice than in germ-free (GF) mice. There was no significant difference in the average number of polyps between GF and gnotobiotic (GB) mice monoassociated with the various strains of intestinal bacteria. However, the incidence of polyposis and the number of polyps per mouse were significantly lower for mice associated with either chloroform-resistant bacteria (CRB) or fusiform bacteria (FB) than for GF mice. This study demonstrated that polyposis was suppressed by FB and CRB in the small intestine of BALB/c mice.