Animal models for the study of infant botulism.

Intestinal infection with Clostridium botulinum was produced by intragastric administration of C. botulinum spores in conventionally reared mice seven to 13 days old but not in younger or older mice. The 50% infective dose of one of the culture strains administered was 170 spores per nine-day-old mouse. Overt botulism did not develop in these animals, but infection with C. botulinum was evidenced by the presence of botulinal toxin in the colon for up to seven days after challenge. Infant mice were at least as sensitive to the lethal action of botulinal toxin as were adult mice, and evidence suggests that infant rats may have a similar age-related susceptibility to enteric botulinal infection. Germfree adult mice were very susceptible to infection with C. botulinum, acquiring intestinally infective doses of airborne spores. Within a few days after exposure to normal mice, the axenic mice became resistant to challenge with 10(5) C. botulinum spores.