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Clostridium botulinum
From Wikipedia, the free encyclopedia
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 Clostridium botulinum stained with gentian violet.
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| Clostridium botulinum van Ermengem, 1896 |
Clostridium botulinum is a bacterium that produces the toxin botulin, the causative agent in botulism.[1] It is included in the genus Clostridium, a major group of Gram-positive forms. C. botulinum was first recognized and isolated in 1896 by Emile van Ermengem and is commonly found in soil.
These rod-shaped organisms grow best in low-oxygen conditions. They form spores that allow them to survive in a dormant state until exposed to conditions that can support their growth.[2]
Each of the seven subtypes of C. botulinum produces a different botulin toxin.[3] These are labeled with letters and are called A to G types. Types C and D are not human pathogens. A "mouse protection" test determines the type of C. botulinum present using monoclonal antibodies.
In the United States, outbreaks are primarily due to types A or B, which are found in soil, or type E, which is found in fish. Optimum temperature for types A and B is 35-40° C. Minimum pH is 4.6. It takes 25 min at 100°C to kill these types. Optimum temperature for type E is 18-25°C. Minimum pH is 5.0. It takes about 0.1 minute at 100°C to kill type E C. botulinum.
Clostridium botulinum is also used to prepare Botox, used to selectively paralyze muscles to temporarily relieve wrinkles. It has other "off-label" medical purposes, such as treating severe facial pain, such as that caused by trigeminal neuralgia.
Botulin toxin produced by Clostridium botulinum is often believed to be a potential bioweapon as it is so potent that it takes less than 1 microgram to kill a person, a drop could kill 100,000 people, and 1 pound of it can kill the entire human population, though contact is uncommon.
Clostridium botulinum is a soil bacterium. The spores can survive in most environments and are very hard to kill. They can survive the temperature of boiling water at sea level, thus many foods are canned with a pressurized boil that achieves an even higher temperature, sufficient to kill the spores.
Growth of the bacterium can be prevented by high acidity, high ratio of dissolved sugar, high levels of oxygen, or very low levels of moisture. For example in a low acid, canned vegetable such as green beans that are not heated hot enough to kill the spores (ie. a pressurized environment) may provide an oxygen free medium for the spores to grow and produce the toxin. On the other hand, tomatoes or tomato sauce are sufficiently acidic to prevent growth; even if the spores are present, they pose no danger to the consumer. Honey, corn syrup, and other sweeteners may contain spores but the spores cannot grow in a highly concentrated sugar solution; however, when a sweetener is diluted in the low oxygen, low acid digestive system of an infant, the spores can grow and produce toxin. As soon as infants begin eating solid food, the digestive juices become too acidic for the bacterium to grow.
- ^ Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology, 4th ed., McGraw Hill. ISBN 0838585299.
- ^ Madigan M; Martinko J (editors). (2005). Brock Biology of Microorganisms, 11th ed., Prentice Hall. ISBN 0131443291.
- ^ Wells CL, Wilkins TD (1996). Botulism and Clostridium botulinum in: Baron's Medical Microbiology (Baron S et al, eds.), 4th ed., Univ of Texas Medical Branch. (via NCBI Bookshelf) ISBN 0-9631172-1-1.
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