An infection of an operative site that typically appears 1 to 2 weeks after surgery, and festers as a result of the combined action of multiple different microorganisms. It is characterized by areas of reddened and inflamed skin surrounding necrotic centers, with communicating tracts or tunnels that ulcerate through the outer layer of skin at neighboring locations. Early institution of appropriate antimicrobial therapy, surgery, and supportive measures are necessary in this potentially life-threatening condition.