A 26 yo M presents to the ED with a chief complaint of R foot pain for 1 month. He has been using an ACE wrap over a wound, but has not changed the bandage in 2 weeks. He reports foul smelling drainage seeping through the bandage. An xray is obtained. What's the diagnosis?  (scroll down for answer)

Answer: Gas gangrene and osteonecrosis of the 5th metatarsal/phalanx  (also note healing fractures with callus formation)

• highly lethal necrotizing soft tissue infection of skeletal muscle caused by toxin and gas-producing Clostridium species
• most cases are traumatic and result from penetrating injury and inoculation of muscle tissue with Clostridium perfringens, an anaerobic bacteria found in sewage and soil
• patients typically present with severe pain at site of injury, followed by skin changes overlying the affected area (pallor--> red/purple discoloration--> blister/bullae formation-->crepitus)
• disease progression is rapid and systemic toxicity and multiorgan failure may occur within hours of presentation
• MRI is more sensitive than xray for diagnosis of gangrene/osteonecrosis, but imaging should not delay treatment
• requires emergent surgical consult, initiation of fluid resuscitation and broad spectrum antibiotic therapy
• definitive diagnosis is made by surgical exploration and demonstration of the organism in tissue