Afebrile tension pyopneumothorax due to anaerobic bacteria: Fistula or gas production?

Pyopneumothorax is characterized by a pleural collection of pus and air requiring emergent thoracic drainage. A 65-year-old diabetic woman presented with a two-week history of fatigue and dyspnea but without fever. Chest computed tomography showed extensive pleural effusion and air in the left pleural cavity, which caused a mediastinal shift with peripheral circulatory failure. There was no evidence of a pulmonary fistula. Anaerobic bacteria were found in the pus smear after microscopy. After 17 days of chest drainage and 18 days of antibiotic treatment, the patient recovered without any complications. The etiology of pyopneumothorax in this case was slowly progressive pyothorax due to gas-producing anaerobic bacteria. In conclusion, we should pay careful attention to serious infectious diseases, including pyothorax, in diabetic patients due to the high prevalence and subclinical symptoms.