Klostridia

Klostridia are a broad group of bacteria within the class Clostridia, often discussed in the context of the genus Clostridium. They are Gram-positive, obligate anaerobes that form endospores, and are typically rod-shaped. Members inhabit soil, sediments, sewage, and the intestinal tracts of humans and animals.

Key characteristics include their anaerobic metabolism and spore formation, which allows survival in harsh conditions. They are diverse in metabolism; some ferment sugars to solvents such as acetone and butanol (e.g., Clostridium acetobutylicum), others produce gases.

Medical relevance: Several species are notable pathogens. Clostridium tetani produces tetanospasmin causing tetanus; Clostridium botulinum produces botulinum toxin causing botulism; Clostridium perfringens causes gas gangrene and food poisoning; Clostridioides difficile causes antibiotic-associated colitis. Toxins disrupt neural or intestinal systems leading to disease. Many infections occur following antibiotic use, or wound contamination.

Taxonomy and nomenclature: The traditional genus Clostridium is polyphyletic; the group includes the new genus Clostridioides, which includes C. difficile. The class Clostridia contains numerous genera beyond Clostridium, reflecting genetic diversity revealed by molecular methods.

Ecological and industrial roles: In soils and sediments they drive fermentation and organic matter degradation; several species are used in industrial microbiology for solvent production or butanol fermentation. Their resilient spores contribute to persistence in environments and medical settings.