Necrotizing fasciitis (infection of soft tissue)

Skin | Dermatology | Necrotizing fasciitis (infection of soft tissue) (Disease)


Description

Necrotizing soft tissue infection is a rare but very severe type of bacterial infection. It can destroy the muscles, skin, and underlying tissue. The word necrotizing refers to something that causes body tissue to die.

Causes and Risk factors

Many different types of bacteria can cause this infection. A very severe and usually deadly form of necrotizing soft tissue infection is due to Streptococcus pyogenes, which is sometimes called flesh-eating bacteria. Necrotizing soft tissue infection develops when the bacteria enters the body, usually through a minor cut or scrape. The bacteria begins to grow and release harmful substances (toxins) that kill tissue and affect blood flow to the area. As the tissue dies, the bacteria enters the blood and rapidly spreads throughout the body.

Bacteria cause most cases of necrotizing fasciitis; only rarely do other organisms such as fungi cause this disease. Group A Streptococcus and Staphylococcus, either alone or with other bacteria, cause many cases of necrotizing fasciitis although Clostridium bacteria should be considered as a cause especially if gas is found in the infected tissue. Because of better microbial isolation techniques for anaerobic bacteria, bacterial genera such as Bacteroides, Peptostreptococcus, and Clostridium are often cultured from the infected area. Frequently, culture of tissue involved by necrotizing fasciitis also yields a mixture of other nonanaerobic bacterial types such as E. coli, Klebsiella, Pseudomonas, and others. Other organisms may rarely cause necrotizing fasciitis, but when they do, the resulting infections are often difficult to treat successfully.

Diagnosis and Treatment

Many investigators conclude that nonanaerobic organisms damage tissue areas enough to cause local areas of hypoxia (reduced oxygen) where anaerobic organisms then can thrive and extend the infection further. This results in polymicrobial infection in which one type of bacteria aids the survival and growth of another type of bacteria (synergy). Infrequently, Vibrio vulnificus causes the disease when a person, usually someone with liver function problems (for example, alcoholics or immunosuppressed patients), eats contaminated seafood or a wound gets contaminated with seawater containing Vibrio vulnificus.

...