Pulmonary actinomycosis in an older adult mimicking refractory bronchial asthma

Abstract

Pulmonary actinomycosis is an uncommon chronic infection caused by Actinomyces species and often mimics tuberculosis, malignancy, or uncontrolled asthma, leading to delayed diagnosis. A 73-year-old woman with bronchial asthma developed progressive nocturnal cough, halitosis, and brownish-black sputum with unintentional weight loss despite good inhaler adherence. Chest radiograph showed right lower lobe consolidation, and high-resolution computed tomography demonstrated fibrosis, ground-glass opacities, and traction bronchiectasis. Sputum was negative for Mycobacterium species but grew Pseudomonas aeruginosa. Bronchoscopy revealed an irregular obstructing lesion in the posterior basal segment of the right lower lobe with necrotic debris. Histopathology (periodic acid–Schiff and Grocott’s methenamine silver stains) demonstrated filamentous organisms consistent with Actinomyces species. She received prolonged oral amoxicillin with two weeks of ciprofloxacin, achieving marked clinical improvement and complete radiological resolution at six months. Early bronchoscopy with tissue diagnosis and prolonged targeted antibiotics are essential in non-resolving pulmonary lesions to prevent recurrence.