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.