Nonclostridial Gas Gangrene Caused by <i>Streptococcus anginosus</i> in a Diabetic Foot: A Case Report of Successful Limb Salvage

Gas gangrene is a life-threatening necrotizing infection classically associated with <i>Clostridium</i> species. Nonclostridial variants, particularly those caused by the <i>Streptococcus anginosus</i> group, are rare but can be clinically indistinguishable from clostridial myonecrosis in patients with diabetes mellitus. A 48-year-old female with uncontrolled diabetes (hemoglobin A1c [HbA1c] 9.0%) presented with a rapidly progressing foot infection following a minor injury. Radiographic imaging revealed extensive soft tissue emphysema and osteolysis in the right foot. Laboratory findings showed severe inflammation (white blood cell count 22,610/μL, high-sensitivity C-reactive protein 27.07 mg/dL). Emergency surgery was performed, involving radical debridement and fifth toe amputation. Initial and intraoperative cultures identified <i>S. anginosus</i> and <i>Streptococcus agalactiae</i>. Following stabilization of the infection through targeted antibiotics and radical debridement, the resulting large defect was successfully reconstructed using a thoracodorsal artery perforator free flap. At the 4-month follow-up, the patient showed excellent wound healing and improved glycemic control (HbA1c 6.2%). This case underscores the unique clinical characteristics of nonclostridial gas gangrene, which can present with aggressive progression similar to classic clostridial infections in diabetic patients. Early differential diagnosis, prompt radical debridement, culture-directed targeted antibiotic therapy, and timely microsurgical reconstruction are essential for successful limb salvage.