The microbiology of transmissible murine colonic hyperplasia.

The relationship of Citrobacter freundii (4280) to the development of colonic hyperplasia in mice was investigated. The number of Citrobacter freundii (4280) in the descending colon were quantitated at intervals following experimental inoculation, and findings were correlated with previously reported histological and ultrastructural findings. Citrobacter freundii (4280) was a transient infection, lasting 2-3 weeks, after which time mice no longer harbored the organism. Neomycin sulfate and tetracycline hydrochloride, when administered in the drinking water, were useful in the prevention of infection as well as ablation of established infection. The presence of Citrobacter freundii (4280) for as little as 2 days was sufficient stimulus to result in detectable mucosal hyperplasia. The longer the bacterium was present, through 10 days, the greater the hyperplasia.