Large Spontaneous Subcutaneous Abscess Formation due to Finegoldia magna in a Diabetic Patient: A Case Report.

Introduction: Finegoldia magna is a member of the Gram-positive anaerobic cocci group and constitutes the flora of the skin and other parts of the body. It sometimes colonizes diabetic foot and rarely infects skin or soft tissue of non-immunocompromised patients.

Case presentation: Here, we report the case of a severe subcutaneous abscess on the back caused by F. magna involving an immunocompromised patient with poorly controlled diabetes. A 48-year-old woman with diabetes mellitus and anemia associated with uterine fibroids was referred to us with a 1-month history of a skin manifestation on her back, with a body temperature of 35.9°C and blood pressure of 115/73 mm Hg. The manifestation involved a subcutaneous mass of 36 × 45 cm with a foul odor, partly covered with necrotic tissue, which had the appearance of a tortoiseshell-like pattern. Blood examination revealed C-reactive protein of 21.4 mg/dL and hemoglobin A1c of 9.1%. Contrast-enhanced computed tomography showed a subcutaneous abscess with internal emphysema. Emergency debridement was performed, resulting in drainage of foul-smelling gray-green pus. F. magna was detected in the pus and skin tissue.

Conclusion: Skin and soft tissue infectious disease caused by F. magna is extremely rare, but the disease tends to become severe once developing in an immunocompromised patient, such as a patient with poorly controlled diabetes. Therefore, physicians should consider F. magna as a causative agent when poorly controlled diabetic patients suffer from severe infectious cutaneous manifestations.