Botulism

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Etiology/Bacteriology

Taxonomy

Domain- Bacteria
Class- Clostridia
Order Clostridiales
Family-Clostridiaceae
Genus- Clostridium
Species C. botulinum

Description

Clostridium botulinum is the bacteria that is responsible for Botulsim. It is a gram positive, rod shaped bacterium that is strictly anaerobic and produces neurotoxins that paralyze host muscular junctions. There are 7 types of toxins, A-G, but only 4 of these, A,B,E,F, have been known to cause disease in humans. The most common toxins in the United States are A,B and E. Throughout the world, toxin A is most prevalent. All toxins are encoded in the bacterial chromosome except type G which is thought to be plasmid encoded. C. Botulinum is only able to produce its toxin during sporulation. The endospores can lie dormant for several years in contaminated foods but will become active once the environmental conditions are favorable. Since the bacteria are obligate anaerobes there should be minimal oxygen present and the pH should be low in the range of 4.8-7. Due to its specific living conditions, it is difficult to grow in the lab. A media culture of tryptose sulfite cycloserine growth media is used the lab setting and there is <2% oxygen in its surrounding area. The bacteria is unable to use lactose as a source of carbon which is a critical biochemical identification when differentiating the organism from other species.

Pathogenesis

Transmission

C. Botulinum can be transmitted through home canned foods, poorly packaged preserved foods, open wounds, injections and honey products. Since spores can be dormant for several years canned foods are highly susceptible for contamination. This bacterium is however not spread person to person. Processed foods such a green beans, corn, and beets are some of the most common infected canned foods because of their low acid content which creates a favorable environment for the spores to germinate and create toxin. Other foods such a fish and commercially processed foods can be contaminated but are less common relative to home canned products. Wound injuries can occur when there is a cut on the body that is then exposed to C. botulinum spores. The spores germinates in the would and begins to produce toxins which are absorbed into the blood stream. The toxins are then able to use the host's circulatory system to deliver and infects neuron cells throughout the body. Wound injuries can occur from cuts on the body or drug related injections. The most common drug associated with Botulism is Black Tar Heroin from Mexico. This has been a growing concern because the drug can be exposed to spores. When injected into the body, germination and relocation occur and begin infecting the host with toxin. Infant botulism occurs when a baby under the age of 1 year eat contaminated foods such as honey. The spores are consumed by the baby and they travel to the gasterointestinal tract where they are able to germinate.

Infectious dose, incubation, and colonization

Epidemiology

Virulence factors

Clinical features

Diagnosis

Treatment

Prevention

Host Immune Response

References

1 Conway, Tyrrell. “Genus conway”. “Microbe Wiki” 2013. Volume 1. p. 1-2.


Created by {Naomi Quillin}, student of Tyrrell Conway at the University of Oklahoma.