Clostridium, genus of gram-positive bacteria (see Gram's stain ), several species of which cause significant, potentially deadly diseases in humans as a result of the toxins that each produces. Clostridium bacteria are rod-shaped and anaerobic, that is, they live in the absence of oxygen; they are common in the soil. C. botulinum, which grows in improperly canned food, produces neurotoxins that when ingested cause the form of food poisoning known as botulism . C. difficile, commonly known as C. diff, is usually transmitted in hospitals and nursing homes as a result of poor personal hygiene and insufficient disinfection; a person taking antibiotics, which kills normal intestinal bacteria, is more susceptible to the bacterium. Infection may cause fever, nausea and abdominal pain, diarrhea, and, in more severe cases, colitis . Infection is most deadly in those over 65 years of age. Since 2001 a more virulent and drug-resistant strain has of C. difficile has developed, making infection increasingly difficult to treat. Treatment typically involves stopping the antibiotic that promoted the infection and taking the antibiotics metronidazole (Flagyl; in milder cases) or vancomycin (in more severe cases); in the most extreme cases, the colon may be surgically removed. C. perfringens infection causes gas gangrene ; it generally occurs in the body where trauma, surgery, or another cause has resulted in diminished blood supply. Within a week, fever and pain at the infection site results as the toxins released by the bacteria kill muscle cells; if untreated, muscle necrosis rapidly develops and spreads, leading to death. Tetanus results when C. tetani infects body tissues through a puncture wound or trauma. C. tetani is common in the digestive tract, but its toxins are destroyed digestive enzymes.

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