TAILIEUCHUNG - Chapter 135. Gas Gangrene and Other Clostridial Infections

Bacteria of the genus Clostridium are gram-positive, spore-forming, obligate anaerobes that are ubiquitous in nature. There are 60 recognized species of clostridia, many of which are generally considered saprophytic. Some of these species are pathogenic for humans and animals, particularly under conditions of lowered oxidation-reduction potential. Infections associated with these organisms range from localized wound contamination to overwhelming systemic disease. The four major disease categories for which clostridia are responsible are intestinal disorders, suppurative deep-tissue infections, skin and soft tissue infections, and bacteremia. . | Chapter 135. Gas Gangrene and Other Clostridial Infections Bacteria of the genus Clostridium are gram-positive spore-forming obligate anaerobes that are ubiquitous in nature. There are 60 recognized species of Clostridia many of which are generally considered saprophytic. Some of these species are pathogenic for humans and animals particularly under conditions of lowered oxidation-reduction potential. Infections associated with these organisms range from localized wound contamination to overwhelming systemic disease. The four major disease categories for which clostridia are responsible are intestinal disorders suppurative deep-tissue infections skin and soft tissue infections and bacteremia. Toxins play a major role in some of these syndromes. Colitis caused by C. difficile is discussed in Chap. 123. Etiology In humans clostridia normally reside in the gastrointestinal tract and in the female genital tract although they occasionally are isolated from the skin or the mouth. Of the known clostridial species at least 30 have been isolated from human infections. Like several other pathogenic anaerobic bacterial species clostridia are quite aerotolerant but they do not grow on artificial media in the presence of oxygen. Clostridia characteristically produce abundant gas in artificial media and form subterminal endospores. C. perfringens one of the most clinically important species is encapsulated and nonmotile and rarely sporulates in artificial media the spores can usually be destroyed by boiling. C. tetani and C. botulinum are discussed in detail in Chaps. 133 and 134 respectively. Clostridia are present in the normal colonic flora at concentrations of 109-1010 g. Of the 30 species that normally colonize humans C. ramosum is the most abundant and is followed in frequency by C. perfringens. These organisms are universally present in soil at concentrations of up to 104 g. C. perfringens strains are classified on the basis of their production of several lethal toxins .

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