Gas Gangrene

Key Features

Essentials of Diagnosis

• Contamination of a wound with soil or feces

• Massive edema, skin discoloration, bleb formation, and pain in an area of trauma

• Serosanguineous exudate from wound

• Crepitation of subcutaneous tissue

• Rapid progression of signs and symptoms

• Clostridia cultured or seen on stained smears

General Considerations

• Gas gangrene (clostridial myonecrosis)

  • Defined as a necrotizing infection that follows trauma or surgery

  • Caused by several anaerobic, gram-positive, spore-forming bacilli of the genus Clostridium

    • Spores are found in soil, feces, and vaginal secretions

    • In devitalized tissue, the spores germinate into vegetative bacilli that proliferate and produce toxins, causing thrombosis, hemolysis, and tissue necrosis

• C perfringens, the species causing approximately 80% of cases of gas gangrene, produces at least eight toxins

• Extremities, abdomen, and uterus are areas involved most often

• Clostridium septicum may also cause myonecrosis and causes septicemia in patients with neutropenia

• Nonclostridial infections with gas formation can mimic clostridial infections and are more common

• Neutropenia is a risk factor for this severe infection

Clinical Findings

Symptoms and Signs

• Sudden onset, often 1 day after trauma or surgery (mean, 3–4 days) but can be delayed up to 20 days

• Pain and swelling usually are intense

• Skin around the wound becomes discolored (pale, red, or purple), with hemorrhagic bullae, serosanguineous exudate, and crepitus

• Absence of crepitus does not rule out the diagnosis

• Systemic illness appears early and progresses rapidly to intravascular hemolysis, jaundice, shock, toxic delirium, and renal failure

Differential Diagnosis

• Gangrene and cellulitis caused by other organisms and clostridial cellulitis (not myonecrosis) must be distinguished

• Necrotizing fasciitis may resemble gas gangrene

Diagnosis

Laboratory Findings

• Isolation of the organism requires anaerobic cultures

• The wound exudate, soft tissue, muscle and blood can be cultured

• Gram-stained smears may demonstrate many gram-positive rods and few inflammatory cells

Imaging

• Radiographs may demonstrate gas in tissues, but this is a late finding

Diagnostic Procedures

• Direct visualization of the muscle at surgery may be necessary to diagnose gas gangrene

• Early, the muscle is pale and edematous and does not contract normally

• Later, the muscle may be frankly gangrenous

Treatment

Medications

• Penicillin G (300,000–400,000 units/kg/d intravenously in six divided doses) should be given

• Clindamycin, metronidazole, meropenem, and ertapenem are alternatives for penicillin-allergic patients

• Some experts recommend a combination of penicillin and clindamycin; clindamycin may inhibit toxin production

Surgery

• Should be prompt and extensive, with removal of all necrotic tissue

• Compartment syndromes

  • Can occur even if there are few cutaneous findings

  • Compartment pressures should be checked in ...