Myonecrosis

Alternative names
Tissue infection - Clostridial; Gangrene - gas; Gas gangrene; Clostridial infection of tissues

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. Staphlococcus aureus and Vibrio vulnificus can also cause similar infections.

Causes, incidence, and risk factors
Gas gangrene occurs as a result of infection by Clostridium bacteria that, under anaerobic (low oxygen) conditions, produce toxins that cause the tissue death and associated symptoms. Gas gangrene is rare, with only 1,000 to 3,000 cases occurring in the United States annually.

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 vascular 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 margins 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 on 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), renal 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.

Signs and tests

Shock may be present, as evidenced by 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 and spore formation 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.

Expectations (prognosis)

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

Complications

     
  • disfiguring or disabling permanent tissue damage  
  • jaundice with liver damage  
  • kidney failure  
  • spread of infection through the body (sepsis)  
  • shock  
  • stupor  
  • delirium  
  • coma

Calling your health care provider

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.

Johns Hopkins patient information

Last revised: December 8, 2012
by Brenda A. Kuper, M.D.

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.