Abstract: Objective To summarize the clinical characteristics of pulmonary actinomycosis in the elderly patients, and to improve the levels of diagnosis and treatment. Methods A retrospective analysis was conducted on the clinical data of 17 elderly inpatients with pulmonary actinomycosis at Peking Union Medical College Hospital from January 2014 to May 2024. Results Among the patients, 9 cases were male and 8 cases were female, with a median age at diagnosis of 67 years. The median age-adjusted Charlson Comorbidity Index (aCCI) was 4 points, with 13 patients presenting with systemic risk factors such as diabetes and immunosuppression, and 4 patients presenting with local risk factors such as periodontal disease. Clinical symptoms were observed in 16 patients, including cough (12 cases), fever (10 cases), sputum production (8 cases), and hemoptysis (5 cases). Laboratory tests revealed that 5 cases showed white blood cell count >9.5×10⁹/L, 8 cases had high sensitivity C-reactive protein (hs-CRP) level >8 mg/L, and 9 cases had erythroayte sedimentation rate (ESR) value>20 mm/h. Chest CT predominantly displayed mass/nodular shadows (7 cases) and cavitary shadows (4 cases). Etiological confirmation pathways included qualified sputum culture (7 cases), bronchoscopic specimen culture (7 cases), tissue biopsy (2 cases), and pleural effusion culture (1 case). In terms of treatment, 12 cases received intravenous antibiotics (10 cases utilized penicillin), 8 cases were treated with oral penicillin, and 12 cases underwent treatment with a combination of ≥2 antibiotics. The median follow-up duration was 5.6 years, with 15 cases achieving cure and 2 cases resulting in death. Conclusions Pulmonary actinomycosis in the elderly is frequently associated with underlying diseases, with clinical manifestations primarily consisting of respiratory symptoms. Imaging features are mainly characterized by mass/cavitary lesions. The positive rate of bronchoscopy and sputum culture is relatively high, and the prognosis is favorable with penicillin-based combination therapy. It is suggested that actinomycosis should be differentiated in elderly patients with respiratory tract infection with risk factors.

Key words: aged, pulmonary actinomycosis, clinical characteristic