[Dermo-hypodermitis and necrotizing fasciitis].

Acute gangrenous dermo-hypodermitis and necrotizing fasciitis are potentially life-threatening infections of skin and soft tissues, which may be difficult to recognize at an early stage. A combination of local signs (erythema, mottling, bullous formation) and of symptoms suggestive of sepsis should prompt early suspicion and therapeutic intervention. Group A streptococci remain the major pathogen involved in necrotizing fasciitis involving extremities, following minor trauma or surgery, and sometimes apparently spontaneously. The most severe form is streptococcal toxic shock syndrome, where production of exotoxins (superantigens) is a major factor contributing to the severity of the syndrome. A number of other pathogens, often combined in mixed aerobic-anaerobic infections may be involved, especially in post-surgical and perineal gangrene. Surgery remains the mainstay of therapy, and should be considered as soon as the clinical suspicion arises. Antibiotic therapy is based on penicillins (penicillin G for streptococcal gangrene, or beta-lactamases penicillins in polymicrobial infections). New therapeutic approaches (clindamycin and immunoglobulins) may be useful in streptococcal toxic shock. The prognosis appears to have improved in recent years with early therapeutic intervention, but remains largely dependent on the severity of the septic response and underlying diseases.