Cecectomy causes long-term reduction of colonization resistance in the mouse gastrointestinal tract.

Removal of the cecum from normal mice caused a major perturbation of the microbial ecology of the gastrointestinal tract. There was a permanent reduction in colonization resistance resulting in a 1,000-fold increase in the concentration of facultatively anaerobic coliform bacteria. The animals were significantly more susceptible to peroral challenge by the intestinal pathogen Salmonella enteritidis. Coincident with this increase in coliform counts and susceptibility to salmonellae was a decrease in the numbers of strictly anaerobic fusiform bacteria that dominate the rodent intestinal tract, resulting in reduced levels of acetic, propionic, and butyric acids. Cecectomized mice are likely to be a useful model for study of the interaction between intestinal pathogens and the normal microbiota and for studies of translocation of bacteria into host tissues after loss of colonization resistance.