Fasciitis - necrotizing

Alternative names

Necrotizing fasciitis; Necrotizing soft tissue infection; 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