Necrotizing fasciitis is a progressive, rapidly spreading deep infection with  subcutaneous necrosis. It occurs more frquently in men and in the lower extremities.  Preceding trauma may be minimal, or there may be a chronic ulcer.

Risk factors include diabetes mellitus, cancer, alcoholism, vascular insufficiency, organ transplants, HIV, or neutropenia.

      There are two types of necrotizing fasciitis:

•  Type 1 is polymicrobial, involves non-group A streptococci and anaerobes, and is usually affects the abdomen and perineum.
• Type 2 is from group A Beta-hemolytic streptococci and affects the extremities.