Clostridium - Overview

Overview

Clostridium consists of around 100 species that include common free-living bacteria as well as important pathogens. There are five main species responsible for disease in humans:

• C. botulinum, an organism that produces botulinum toxin in food/wound and can cause botulism. Honey sometimes contains spores of Clostridium botulinum, which may cause infant botulism in humans one year old and younger. The toxin eventually paralyzes the infant's breathing muscles. Adults and older children can eat honey safely, because Clostridium do not compete well with the other rapidly growing bacteria present in the gastrointestinal tract. This same toxin is known as "Botox" and is used cosmetically to paralyze facial muscles to reduce the signs of aging; it also has numerous therapeutic uses.

• C. difficile, which can flourish when other bacteria in the gut are killed during antibiotic therapy, leading to pseudomembranous colitis (a cause of antibiotic-associated diarrhea).

• C. perfringens, formerly called C. welchii, causes a wide range of symptoms, from food poisoning to gas gangrene. Also responsible for enterotoxemia (also known as "overeating disease" or "pulpy kidney disease") in sheep and goats. C. perfringens also takes the place of yeast in the making of salt rising bread. The name perfringens means 'breaking through' or 'breaking in pieces'.

• C. tetani, the causative organism of tetanus. The name derives from "of a tension", referring to the tension (caused by tetanus) in the muscles.

• C. sordellii can cause a fatal infection in exceptionally rare cases after medical abortions. Less than one case per year has been reported since 2000.

Clostridium is sometimes found in raw swiftlet nests, a Chinese delicacy. Nests are washed in a sulfite solution to kill the bacteria before being exported to the U.S.

Neurotoxin production is the unifying feature of the species C. botulinum. Seven types of toxins have been identified and allocated a letter (A-G). Most strains produce one type of neurotoxin but strains producing multiple toxins have been described. C. botulinum producing B and F toxin types have been isolated from human botulism cases in New Mexico and California. The toxin type has been designated Bf as the type B toxin was found in excess of the type F. Similarly, strains producing Ab and Af toxins have been reported. Organisms genetically identified as other Clostridium species have caused human botulism; Clostridium butyricum producing type E toxin and Clostridium baratii producing type F toxin. The ability of C. botulinum to naturally transfer neurotoxin genes to other Clostridium species is concerning, especially in the food industry where preservation systems are designed to destroy or inhibit only C. botulinum but not other Clostridium species.