A 32-year-old male construction worker from Delhi presents to the primary health centre with a 3-week history of productive cough, fever, and night sweats. Chest X-ray shows an upper lobe infiltrate with cavitation. Sputum smear microscopy is positive for acid-fast bacilli (AFB). His household contacts include his wife (28 years, non-pregnant) and two children aged 6 and 9 years. What is the most appropriate next step in management?