Infection	Patient history	Underlying conditions	Physical examination findings
Group A Streptococcus species	Skin abrasion, trauma, recent herpes zoster infection, human bite, intravenous drug abuse	Diabetes, cancer, alcoholism, stasis dermatitis	Intense erythema, edema, lymphadenopathy, hemorrhagic and necrotic bullae
Staphylococcus aureus	Skin trauma, recent hospitalization or surgery, intravenous drug abuse	Obesity, diabetes, immunocompromising condition	Furuncles, local abscesses, diffuse macular erythroderma
Polymicrobial	Diabetic foot ulcer, recent surgery	Diabetes, immunocompromising condition, vascular disease	Moist gangrene with a foul odor
Pseudomonas species	Bacteremia, moist skin infection, severe burn, recent hospitalization	Immunocompromising condition	Hemorrhagic and necrotic bullae
Vibrio vulnificus	Exposure to raw or undercooked seafood or seawater	Liver disease, immunocompromising condition	Hemorrhagic and necrotic bullae, ecchymoses
Clostridium perfringens	Severe trauma with wound contamination, recent surgery, intravenous drug abuse	None	Pale skin, edema, hemorrhagic and necrotic bullae, foul-smelling discharge, gas formation
Pasteurella multocida	Cat or dog bite	None	Erythema, edema, serosanguineous discharge, lymphadenitis, tenosynovitis
Aeromonas hydrophila	Exposure to freshwater, skin abrasion	Usually none; sometimes an immunocompromising condition	Erythema, bullae, necrosis, possible gas formation