Colonization of the intestinal tract of mice with Clostridium tetani

Colonization of intragastrically inoculated Clostridium tetani in intestinal tract of mice was investigated by cultivation of daily stool samples and quantification of the bacilli over a period of 3 weeks. We found that most of the inoculum was excreted in the stool during the first 24 hr. The amount of C. tetani recovered on the second day after inoculation was very small. C. tetani apparently thrived in the intestinal tract when more than 6 log colony forming units (CFU) of tetanus spores had been inoculated. Otherwise, C. tetani colonized poorly in intestinal tract. Tetanus toxin was not detected in the stool nor in the contents of the small and large intestines 24 hr after 6.23 log CFU of tetanus spores had been inoculated. We concluded that the intestinal cavity of mouse is not a favorable environment for colonization of C. tetani under natural conditions.