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Microbial ecological basis of infant botulism as studied with germfree mice
Abstract:
The possible role of the indigenous intestinal microflora in the toxicoinfection of human infant botulism was studied with adult germfree mice. Intraintestinal botulinum monoassociation was consistently produced when mice were fed 10 C. botulinum type A spores. Control germfree mice became enterically infected when placed in the same isolator with, but separated from, animals that had been fed spores. When transferred into a room holding a colony of normal mice, the highly susceptible gnotobiotes became resistant to challenge of 10(5) spores after about 3 days of the conventionalizing exposure. The findings are interpreted as evidence that enteric botulinum infection occurs in human infants whose intestinal tract has not yet been colonized by bacteria which are indigenous to adults and prevent growth of C. botulinum. Intestinal monoassociation could not be developed in germfree infant mice younger than 7 days.
Insights
Indigenous gut bacteria prevent infant botulism. Germfree mice showed that colonization by normal gut flora protects against Clostridium botulinum infection, a key factor in infant botulism.
Area of Science:
- Microbiology
- Gastroenterology
- Toxicology
Background:
- Human infant botulism is a toxicoinfection caused by Clostridium botulinum.
- The role of indigenous intestinal microflora in preventing this infection is not fully understood.
Purpose of the Study:
- To investigate the protective role of adult intestinal microflora against Clostridium botulinum colonization in germfree mice.
Main Methods:
- Germfree adult mice were monoassociated with Clostridium botulinum type A spores.
- Control mice were exposed to colonized mice.
- Susceptible mice were conventionalized with normal mouse flora and then challenged with spores.
Main Results:
- Intraintestinal botulinum monoassociation was established in germfree mice.
- Conventionalization with normal flora conferred resistance to Clostridium botulinum challenge within 3 days.
- Germfree infant mice younger than 7 days could not develop intestinal monoassociation.
Conclusions:
- The absence of indigenous intestinal bacteria in infants makes them susceptible to botulism.
- Colonization by adult-type gut bacteria prevents Clostridium botulinum growth and subsequent infection.