necrotizing fasciitis, a quickly progressing infection of the skin that spreads along the fascia, the tissue that covers the muscles. (Necrotizing infections that spread along the outer skin layers are known as necrotizing cellulitis.) Necrotizing fasciitis is most commonly caused by toxins released by a strain of Group A streptococcal bacteria ( S. pyrogenes; see streptococcus), but it also may be caused by Staphylococcus aureus (see staphylococcus); other bacteria may also be present.
Popularly known as "flesh-eating disease," the infection typically begins as a warm, very painful red swelling, sometimes at the site of a minor injury. Patients usually have a high fever and may feel ill, dizzy, and confused; the infection spreads rapidly, and tissue in older infected areas turns purplish or black as it dies. Necrotizing fasciitis is treated with surgery (to remove infected tissue) and intravenous antibiotics (high-dose penicillin and clindamycin). If not treated promptly, the toxins produced by the bacteria can cause septic shock and lead to death within 24 hours; roughly 30% of infected patients die.