Necrotizing fasciitis is a rare bacterial infection that can destroy skin and the soft tissues beneath it, including fat and the tissue that covers the muscles (fascia). Necrotizing fasciitis is also referred to as "flesh-eating" bacteria, because these tissues often die rapidly.

Necrotizing fasciitis is caused by several kinds of bacteria. It is most often caused by group A streptococcal (GAS) bacteria. These bacteria also cause other, usually mild, infections such as strep throat or impetigo. But in rare cases the bacteria produce poisons (toxins) that damage the soft tissue below the skin and cause a more dangerous infection that can spread quickly along the fascia. The bacteria also can travel through the blood to the lungs and other organs. Necrotizing fasciitis can cause organ failure and sometimes death.

This condition is treated with antibiotics and supportive care. Surgery is usually needed to remove dead or infected tissue, stop the spread of infection, and repair the damage done by the infection.