Necrotizing fasciitis is a rare bacterial infection that can destroy skin and the soft tissues beneath it, including fat and the tissue covering the muscles (fascia). Because these tissues often die rapidly, a person with necrotizing fasciitis is sometimes said to be infected with "flesh-eating" bacteria, especially Streptococcus pyrogenes.
Necrotizing fasciitis is a severe infection that leads to necrosis of the subcutaneous tissue and adjacent fascia. The usual cause is a mixture of aerobic and anaerobic organisms, although group A streptococcus alone may be responsible.
The organisms reach the subcutaneous tissue by extension from a contiguous infection or trauma to the area, includings surgery. There is widespread damage to the surrounding tissue, and occlusion of small subcutaneous vessels leads to dermal gangrene. Extensive surgical incision and debridement is the mainstay of treatment, with concomitant antibiotic therapy. There are various other necrotizing conditions that are clinically very difficult to distinguish from one another and from necrotizing fasciitis.
The spread of all types of GAS infection can be reduced by thorough handwashing, especially after coughing, sneezing, after caring for persons with wounds or "strep throat," before preparing foods and before eating. Both the organism and the patient susceptibility likely play a role in the development of the infection. While most group A streptococci cause only mild infections (e.g., "strep throat") some types may cause more severe disease. One factor that may be linked to the development of necrotizing fasciitis is the production of proteases (enzymes that break down proteins) by some group A streptococci. Susceptibility of the individual is also important. Investigation of family clusters has shown that the same type of bacteria can cause severe illness in one family member and only mild or no illness in others.
The most frequent cause of necrotizing fasciitis is Streptococcus A, which you may know better as "strep throat," an extremely common infection that almost everyone in America has suffered at one time or another. (There are other causes of necrotizing fasciitis, but they're even more rare than the already rare strep version). The strep bacteria is spread through direct contact, and occasionally through coughing, kissing and other mucous-swapping activities. You can be a carrier of strep without showing any symptoms, but a 24-hour round of antibiotics is usually enough to render a victim non-contagious.
The most common effect of a strep infection is a sore throat. The next-most severe version of strep is called impetigo, a minor outbreak of skin blisters. According to the National Library of Medicine, impetigo "begins as an itchy, red sore that blisters, oozes and finally becomes covered with a tightly adherent crust. It tends to grow and spread. ... The infection is carried in the fluid that oozes from the blisters." Strep throat almost never becomes necrotizing fasciitis, at least from a statistical viewpoint (and you know what they say about statistics). But when your impetigo is impetigo-going-gone, you just might have a case of streptococcal toxic shock syndrome (if you're lucky) or necrotizing fasciitis (if you're not).
Necrotizing fasciitis often occurs in persons with wounds due to surgery or injury that become infected. Persons with such wounds should take appropriate precautions to keep wounds clean and should seek medical attention of signs of infection occur (redness, swelling, area warm to the touch, pus). The infection can be treated with antibiotics.
Treatment of necrotizing fasciitis is most effective if the infection is recognized in time. Antibiotics and surgical removal of dead tissue are required. If the tissue destruction is widespread, extensive surgery or amputation might be the only way to prevent death. While early diagnosis and treatment are the key to preventing devastating tissue destruction, physicians and patients often fail to recognize necrotizing fasciitis and its severity. Being rare, and with an onset that resembles flu-like symptoms, it is often missed until the infection has advanced. One alerting sign is unusually severe pain - far greater than normal for a cut or wound - and painful lymph nodes. For example, a cut on the toe or a surgical leg wound, followed some hours later by severe pain either in the toe, leg, or in the groin (as the infection travels to the lymph nodes), can warn of this potentially deadly, fast-spreading infection.