Clostridial infections

Diagnosis The diagnosis of clostridial disease, in association with positive cultures, must be based primarily on clinical findings. Because of the presence of clostridia in many wounds, their mere isolation from any site, including the blood, does not necessarily indicate severe disease. Smears of wound exudates, uterine scrapings, or cervical discharge may show abundant large gram-positive rods as well as other organisms. Cultures should be placed in selective media and incubated anaerobically for identification of clostridia.

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Gas Gangrene (Clostridial Myonecrosis) Gas gangrene is characterized by rapid and extensive necrosis of muscle accompanied by gas formation and systemic toxicity and occurs when bacteria invade healthy muscle from adjacent traumatized muscle or soft tissue. The infection originates in a wound contaminated with clostridia. Although 30% of deep wounds are infected with clostridia, the incidence of clostridial myonecrosis is quite low. These infections occur in both military and civilian settings.

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Clinical Manifestations Intestinal Disorders Food Poisoning C. perfringens, primarily type A, is the second or third most common cause of food poisoning in the United States (Chap. 122). The responsible toxin is thought to be a cytotoxin produced by 75% of strains isolated from cases of foodborne disease. The cytotoxin binds to a receptor on the small-bowel brush border and induces a calcium ion–dependent alteration in permeability. The associated loss of ions alters intracellular metabolism, resulting in cell death.

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Harrison's Internal Medicine Chapter 135. Gas Gangrene and Other Clostridial Infections Definition 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.

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Spontaneous nontraumatic clostridial myonecrosis (gas gangrene). A man in his 50s presented with severe pain in the right upper extremity. Over several hours, he developed progressive swelling and discoloration in that extremity (A), with hemorrhagic ecchymoses and bullae (B). Gram's stain of aspirate from bullous lesions revealed gram-positive bacilli (C). The patient underwent amputation of the extremity. Tissue Gram's stain (D) also showed gram-positive bacilli, and surgical cultures grew C. septicum.

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