Case report: Aberrant fecal microbiota composition of an infant diagnosed with prolonged intestinal botulism.

Background: Intestinal botulism is primarily reported in small babies as a condition known as infant botulism. The condition results from the ingestion of environmental or foodborne spores of botulinum neurotoxin (BoNT) producing Clostridia, usually Clostridium botulinum, and subsequent spore germination into active botulinum neurotoxinogenic cultures in the gut. It is generally considered that small babies are susceptible to C. botulinum colonization because of their immature gut microbiota. Yet, it is poorly understood which host factors contribute to the clinical outcome of intestinal botulism. We previously reported a case of infant botulism where the infant recovered clinically in six weeks but continued to secrete C. botulinum cells and/or BoNT in the feces for seven months.

Case Presentation: To further understand the microbial ecology behind this exceptionally long-lasting botulinum neurotoxinogenic colonization, we characterized the infant fecal microbiota using 16S rRNA gene amplicon sequencing over the course of disease and recovery. C. botulinum could be detected in the infant fecal samples at low levels through the acute phase of the disease and three months after recovery. Overall, we observed a temporal delay in the maturation of the infant fecal microbiota associated with a persistently high-level bifidobacterial population and a low level of Lachnospiraceae, Bacteroidaceae and Ruminococcaceae compared to healthy infants over time.

Conclusion: This study brings novel insights into the infant fecal composition associated with intestinal botulism and provides a basis for a more systematic analysis of the gut microbiota of infants diagnosed with botulism. A better understanding of the gut microbial ecology associated with infant botulism may support the development of prophylactic strategies against this life-threatening disease in small babies.