A 66 yo male hx of DM presents to the ED with right foot pain.  Reports that he started with a wound on his great toe but that the pain and swelling have progressed to his entire foot over the past week.  On exam, foot is swollen, has foul odor, and there are areas of necrosis.  An x-ray is shown.  What's the diagnosis?  Scroll down for answer.

Answer:  gas gangrene

• Gangrene is a broad term for ischemia and necrosis in any tissue, usually related to poor blood supply
• dry gangrene: describes gradual progressive necrosis due to poor arterial supply
• wet gangrene: more typically venous obstruction and poor blood flow, prone to bacterial infections
• gas gangrene: life threatening necrotizing soft tissue infection
• Risk factors: uncontrolled DM, vascular disease, alcoholism, chronic skin infection, immunosuppression, smoking
• Most commonly polymicrobial (Gram positivie cocci, Gram negative rods, anaerobes), but can also be caused by Group A Strep, Vibrio vulnificus, fungus, Clostridia
• Often starts with initially more minor skin injuries but gas gangrene is rapidly progressive
• x-ray may miss gas in deeper tissues - obtain a CT with high suspicion
• Treatment
• Surgery is gold standard and reduces mortality
• Broad spectrum antibiotics
• Tetanus immuniztion
• Hyperbaric oxygen

References

Kelly EW, Magilner D. Soft Tissue Infections. In: Tintinalli JE, Stapczynski J, Ma O, Yealy DM, Meckler GD, Cline DM. eds.Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 8eNew York, NY: McGraw-Hill; 2016.

Al Wahbi A. Autoamputation of diabetic toe with dry gangrene: a myth or a fact?. Diabetes Metab Syndr Obes. 2018;11:255–264. Published 2018 Jun 1. doi:10.2147/DMSO.S164199