Kinetics of early cholera infection in the removable intestine tie-adult rabbit diarrhea model

The colonization of the small intestine of adult rabbits challenged with 5 x 10⁷ cells of Vibrio cholerae strain Ogawa 395 has been examined in the removable intestinal tie-adult rabbit diarrhea (RITARD) model. During the first 6 h of infection, numbers of both free and adherent vibrios increased at a rate representing a generation time of about 71 min. Detectable fluid output in response to infection began at about 4 to 5 h postchallenge, and overt diarrhea was observed as early as 11 h. By 8 h after challenge, adherent V. cholerae reached a saturation concentration on the intestinal epithelium of approximately 5 x 10⁸ cells per g of intestine, whereas numbers of free cells continued to increase at an exponential rate for at least 12 to 14 h. The concentration of adherent cells remained relatively constant at the saturation level during this period. This saturation level was similar in all parts of the small intestine. The concentration of adherent organisms increased significantly in moribund animals, suggesting that factors responsible for the earlier saturation equilibrium began changing as animals neared death.