Necrotizing fasciitis

Alternative names
Necrotizing soft tissue infection; Fasciitis - necrotizing; Flesh-eating bacteria; Soft tissue gangrene; Gangrene - soft-tissue

Definition
Necrotizing soft-tissue infection is a severe type of tissue infection that can involve the skin, subcutaneous fat, the muscle sheath (fascia), and the muscle. It causes gangrenous changes, tissue death, systemic disease, and frequently death.

Causes, incidence, and risk factors
Necrotizing subcutaneous infection or fasciitis can be caused by a variety of bacteria including oxygen-using bacteria (aerobic) or oxygen-avoiding bacteria (anaerobic). A very severe and usually fatal fasciitis is caused by a virulent species of streptococcus that is often referred to as the “flesh-eating bacteria” by the press.

This type of infection develops when bacteria enter the body, usually through a minor skin injury or abrasion. The bacteria begin to grow and release toxins that:

     
  • Directly kill tissue  
  • Interfere with the blood flow to the tissue  
  • Digest materials in the tissue which then allows the bacteria to spread rapidly  
  • Cause widespread effects, such as shock

Infection may begin as a small reddish painful spot or bump on the skin. This quickly changes to a painful bronzed or purplish patch that expands rapidly. The center may become black and dead (necrotic). The skin may break open. Visible expansion of the infection may occur in less than an hour.

Symptoms may include fever, sweating, chills, nausea, dizziness, profound weakness, and finally shock. Without treatment death can occur rapidly.

Symptoms

     
  • Severe pain in the area  
  • Swelling in the area  
  • Discoloration in the area       o May appear reddened, bronzed, bruised, or purple (purpuric)       o Progresses to dusky, dark color  
  • Bleeding into the skin  
  • Visibly dead (necrotic) tissue  
  • Patchy skin color  
  • Skin breaks (open wound)  
  • Skin around the wound feels hot and looks reddened, raised, or discolored (inflamed)  
  • Oozing fluid ranging from yellowish clear or yellowish bloody to puslike in quality  
  • Fever  
  • General ill feeling

Signs and tests

The appearance of the skin and underlying tissues and presence of gangrenous changes (black or dead tissue) indicates a necrotizing soft tissue infection. Imaging tests, such as CT scans, are sometimes helpful.

Often a patient will need to go to the operating room so a surgeon can diagnose such an infection. A Gram stain and culture of drainage or tissue from the area may reveal the bacteria to blame.

Treatment

Powerful, broad-spectrum antibiotics must be administered immediately. They are given in a vein to attain high blood levels of the antibiotic in an attempt to control the infection. Surgery is required to open and drain infected areas and remove dead tissue.

Skin grafts may be required after the infection is cleared. If the infection is in a limb and cannot be contained or controlled, amputation of the limb may be considered. Sometimes pooled immunoglobulins (antibodies) are given by vein to help fight the infection.

If the organism is determined to be an oxygen-avoiding bacteria (anaerobe) the patient may be placed in a hyperbaric oxygen chamber, a device in which the patient is exposed to 100% oxygen at several atmospheres of pressure.

Expectations (prognosis)

Outcomes are variable. The type of infecting organism, rate of spread, susceptibility to antibiotics, and how early the condition was diagnosed all contribute to the final outcome.

Scarring and deformity are common with this type of disease. Fatalities are high even with aggressive treatment and powerful antibiotics. Untreated, the infection invariably spreads and causes death.

Complications

     
  • local spread of infection, progressive tissue damage  
  • systemic spread of infection, sepsis, shock  
  • scarring and disfigurement  
  • functional loss of a limb  
  • death

Calling your health care provider
This disorder is severe and may be life-threatening, so consult your health care provider immediately.

Call your health care provider if signs of infection occur around a skin injury: pain, swelling, redness, drainage of pus or blood, fever, or other similar symptoms.

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

Johns Hopkins patient information

Last revised: December 5, 2012
by Potos A. Aagen, M.D.

Medical Encyclopedia

  A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | 0-9

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.