A 52-year-old man from rural India presents with a 6-month history of progressive dyspnea, chest pain, and recurrent cough productive of blood-tinged sputum. Chest X-ray shows bilateral upper lobe infiltrates with cavitation. Sputum smear microscopy is positive for acid-fast bacilli on three occasions. He is otherwise systemically well with no fever. What is the most appropriate next step in management?