Gas gangrene

Definition

Gas gangrene is a severe form of gangrene (tissue death) usually caused by Clostridium perfringens (see also necrotizing subcutaneous infection). It can also be from Group A Streptococcus. Staphylococcus aureus and Vibrio vulnificus can cause similar infections.

Alternative Names

Tissue infection - Clostridial; Gangrene - gas; Myonecrosis; Clostridial infection of tissues

Causes

Gas gangrene occurs as a result of infection with Clostridium bacteria that, under anaerobic (low oxygen) conditions, produce toxins that cause tissue death and associated symptoms. Gas gangrene is rare, with only 1,000 - 3,000 cases yearly in the U.S.

Gas gangrene generally occurs at the site of trauma or a recent surgical wound. About a third of cases occur spontaneously. Patients who develop this disease spontaneously often have underlying blood vessel disease (atherosclerosis or hardening of the arteries), diabetes, or colon cancer.

The onset of gas gangrene is sudden and dramatic. Inflammation begins at the site of infection as a pale-to-brownish-red and extremely painful tissue swelling. Gas may be felt in the tissue as a crackly sensation when the swollen area is pressed with the fingers. The edges of the infected area expand so rapidly that changes are visible over a few minutes. The involved tissue is completely destroyed.

Clostridium bacteria produce many different toxins, four of which (alpha, beta, epsilon, iota) can cause potentially fatal syndromes. In addition, they cause tissue death (necrosis), destruction of blood (hemolysis), local decrease in circulation (vasoconstriction), and leaking of the blood vessels (increased vascular permeability).

These toxins are responsible for both the local tissue destruction and the systemic symptoms (the other symptoms that occur throughout the body).

Systemic symptoms develop early in the infection. These consist of sweating, fever, and anxiety. If untreated, the individual develops a shock -like syndrome with decreased blood pressure (hypotension), kidney failure, coma, and finally death.

Symptoms

• Moderate-to-severe pain around a skin injury
• Progressive swelling around a skin injury
• Moderate-to-high fever
• Skin color initially pale, later dusky progressing to dark red or purple
• Vesicle formation, coalescent (combine into large blisters)
• Blisters filled with brown-red fluid
• Drainage from the tissues, foul-smelling brown-red or bloody fluid (serosanguineous discharge)
• Increased heart rate (tachycardia)
• Sweating
• Subcutaneous emphysema (air under the skin)

Note: Symptoms usually begin suddenly and rapidly worsen.

Exams and Tests

The person may be in shock, with general pallor, cold extremities, low blood pressure, and rapid heart rate. Air in the tissues (crepitus) may be felt. Infection involving the entire body (systemic toxicity or sepsis) may develop. Yellow skin color associated with the excessive breakdown of blood cells (jaundice) is possible.

• A gram stain of fluid from the infected area may shows Gram-positive rods (Clostridium species) or other bacterial types
• A culture may grow the bacteria causing the infection
• Blood cultures may grow the infecting bacteria
• An anaerobic tissue and/or fluid culture may reveal Clostridium species
• An x-ray, CT scan, or MRI of the area may show gas in the tissues

Treatment

Prompt surgical removal of dead, damaged, and infected tissue (debridement) is necessary. Amputation of an arm or leg may be indicated to control the spread of infection.

Antibiotics, preferably penicillin-type, should be given. Initially, this is given intravenously (through a vein). Analgesics may be required to control pain. Hyperbaric oxygen has been tried with varying degrees of success.

Outlook (Prognosis)

Gas gangrene is progressive and often lethal. Immediate medical attention is required.

Possible Complications

• Disfiguring or disabling permanent tissue damage
• Jaundice with liver damage
• Kidney failure
• Spread of infection through the body (sepsis)
• Shock
• Stupor
• Delirium
• Coma

When to Contact a Medical Professional

Call your heath care provider if signs of infection occur at any time around a skin wound -- including pain, swelling, redness, drainage of pus or blood, fever, or similar symptoms.

Go to the emergency room or call the local emergency number (such as 911), if symptoms indicate gas gangrene. This is an emergency condition requiring immediate medical attention!

Prevention

Clean any skin injury thoroughly. Watch for signs of infection (such as redness, pain, drainage, or swelling around a wound), and consult your health care provider promptly if these occur.