Klostridium

Klostridium, commonly written Clostridium in English, is a genus of Gram-positive, obligate anaerobic, spore-forming bacilli. Members are widespread in soil, sediments, and the gastrointestinal tracts of animals and humans. They survive harsh conditions by producing endospores that resist heat and drying, enabling persistence in the environment and during food processing.

Most species are obligate anaerobes that ferment a variety of substrates. They are typically non-motile or motile by peritrichous flagella and form conspicuous endospores. They inhabit soil, sewage, sediments, and the intestines of animals, where they contribute to digestion and, in some cases, pathology.

Medical significance: Several species are pathogenic. Clostridium botulinum produces botulinum toxin causing botulism; Clostridium tetani produces tetanus toxin; Clostridium perfringens can cause gas gangrene and food poisoning; Clostridioides difficile, formerly Clostridium difficile, causes antibiotic-associated diarrhea and colitis. Diagnosis relies on toxin detection or culture; treatment may include antitoxins, antibiotics, surgical debridement, and fecal microbiota transplantation for C. difficile infections.

Taxonomy: The genus has been revised with molecular methods; many species formerly placed in Clostridium are now assigned to other genera, such as Clostridioides. The name Clostridium derives from Greek for spindle-shaped, and Klostridium is a nonstandard variant used in some languages.

Laboratory handling: Clostridia are strict anaerobes requiring specialized culture techniques and safety considerations because some species produce potent toxins.