What mechanism is responsible for botulism in infants caused by Clostridium botulinum?

The mechanism responsible for botulism in infants caused by Clostridium botulinum is the ingestion of spores in food or liquid. Infants, particularly those under one year old, have immature gastrointestinal systems that are not yet fully equipped to eliminate spores of C. botulinum. When these spores are ingested, they can germinate in the intestines and produce the botulinum toxin, which is a potent neurotoxin. This toxin interferes with normal neurotransmission, leading to the characteristic symptoms of botulism, such as weakness, diminished muscle tone, and respiratory distress.

The other options reference different mechanisms that are not relevant for infant botulism. For instance, ingestion of preformed toxin in food is more associated with botulism in adults, where the toxin is produced in anaerobic environments before consumption. Virulence of the organism refers to the overall pathogenicity and factors that contribute to disease but doesn’t specifically pinpoint the mechanism at work in infants. Lipase activity is unrelated to C. botulinum's toxin production or the pathogenesis of botulism itself. Thus, the correct understanding focuses on the unique vulnerabilities of infants regarding spore ingestion.