15.1.1.2.1: Clostridium botulinum

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Gram stain of *C. botulinum*. Spores are stained pink; bacilli stain purple. Photo credit: George Lombard, Centers for Disease Control and Prevention. (Accessed through ASM Image Gallery https://www.asmscience.org/content/e...n/imagegallery)

Organism

Clostridium botulinum is a large, Gram-positive endospore-forming rod
Like all Clostridia, C. botulinum is a strict anaerobe
Able to use a wide variety of sugars and other biological material as carbon and energy sources
Cannot grow in pHs of 4.5 or lower

Habitat

Widely distributed in the environment, usually soil, lake sediment, and decaying vegetation

Source

Food can be contaminated with endospores. When preserved through canning or otherwise stored anaerobically, the endospores germinate and produce exotoxin.
Endospores are often found in raw honey. When ingested by infants who do not have established natural flora, this can lead to gastrointestinal infection.

Epidemiology

Naturally occurs infrequently and sporadically
Most cases are intoxication through contaminated food rather than infection
Infection can occur in infants through ingestion of endospores

Clinical Disease

Toxin inhibits acetylcholine release leading to flaccid paralysis (cannot contract muscles).
Early symptoms appear within about a day and include weakness, dizziness and dryness of the mouth. Other gastrointestinal symptoms may be present.
In later disease, it becomes difficult to speak and swallow, muscle weakness increases, and eventually the diaphragm can be paralyzed
Primary treatment is antitoxin and supportive therapy
Without treatment, mortality rate is >60%, but with treatment it is ~4-20%

Primary Virulence Factors

The only virulence factor is botulinum toxin (link to info in textbook)

Additional information: http://textbookofbacteriology.net/clostridia_4.html