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Clostridia are spore-forming, gram-positive bacilli present widely in dust, soil, and vegetation and as normal flora in mammalian GI tracts.
Nearly 100 Clostridium sp have been identified, but only 25 to 30 commonly cause human or animal disease.
Pathophysiology
The pathogenic species produce tissue-destructive and neural exotoxins that are responsible for disease manifestations. Clostridia may become pathogenic when tissue O2 tension and pH are low. Such an anaerobic environment may develop in ischemic or devitalized tissue, as occurs in primary arterial insufficiency or after severe penetrating or crushing injuries. The deeper and more severe the wound, the more prone the patient is to clostridial infection, especially if there is even minimal contamination by foreign matter. Clostridial disease can also occur after injection of street drugs. Serious noninfectious disease can occur after ingestion of home-canned foods in which clostridia have produced toxins.
Diseases Caused by Clostridia
Diseases caused by clostridia (see Anaerobic Bacteria: Selected Conditions Associated With Clostridial Infections ) include
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Table 1
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| Selected Conditions Associated With Clostridial Infections |
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Condition
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Agent
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Toxin
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Soft-tissue infection: Crepitant cellulitis, myositis, clostridial myonecrosis
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C. perfringens
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α-Toxin (others)
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Hemolysis
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C. perfringens
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Phospholipase C
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α-Toxin
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Muscle necrosis
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C. perfringens
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θ-Toxin
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Enteric diseases
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Food poisoning
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C. perfringens type A
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Enterotoxin
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C. perfringens type C
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β-Toxin
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Antibiotic-associated colitis
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C. difficile
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Possibly toxin A or B*
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Neutropenic enterocolitis
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C. septicum (others)
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Unknown, possibly β-toxin
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C. septicum
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Hemolysis by septicolysine
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C. septicum
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δ-Toxin
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Tissue necrosis
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C. septicum
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α-Toxin
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DNA lysis by DNase
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C. septicum
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β-Toxin
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Hyaluronan lysis by hyaluronilase
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C. septicum
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γ-Toxin
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Neurologic syndromes
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C. tetani
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Tetanospasmin
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C. botulinum
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Botulinal toxins A–G
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Abdominal infections: Cholecystitis, peritonitis, ruptured appendix, bowel perforation, neutropenic enterocolitis
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C. perfringens , C. ramosum (many others)
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β-Toxin
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*Requires further study.
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The most frequent clostridial infection is minor, self-limited gastroenteritis, typically due to C. perfringens
type A. Serious clostridial diseases are relatively rare but can be fatal. Abdominal disorders, such as cholecystitis, peritonitis, ruptured appendix, and bowel perforation can involve C. perfringens, C. ramosum, and many others. Muscle necrosis and soft-tissue infection, which is characterized by crepitant cellulitis, myositis, and clostridial myonecrosis, can be caused by C. perfringens. Tissue necrosis can be caused by C. septicum. Clostridia also appear as components of mixed flora in common mild wound infections; their role in such infections is unclear.
Hospital-acquired clostridial infection is increasing, particularly in postoperative and immunocompromised patients. Severe clostridial sepsis may complicate intestinal perforation and obstruction.
Last full review/revision August 2009 by Joseph R. Lentino, MD, PhD
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