Tuberculous Arthritis

A 28-year-old woman from Delhi presents with a 4-month history of progressive pain and swelling in her right ankle and left knee. She reports night sweats, loss of appetite, and a persistent dry cough. On examination, both joints are warm and swollen with restricted motion. Chest X-ray shows apical infiltrates. Synovial fluid from the knee joint shows 1200 cells/μL with 85% lymphocytes, protein 6.1 g/dL, glucose 28 mg/dL (serum glucose 95 mg/dL), negative Gram stain, and negative bacterial culture. AFB culture is pending. What is the most likely diagnosis?

A 32-year-old man from rural Maharashtra presents with a 6-month history of progressive swelling and pain in his left knee. He reports low-grade fever in the evenings and unintentional weight loss of 8 kg. On examination, the knee is warm, swollen, and shows restricted range of motion. There is no erythema or skin ulceration. X-ray shows marginal erosions and joint space narrowing. Synovial fluid analysis reveals 200 cells/μL (predominantly lymphocytes), protein 5.2 g/dL, glucose 35 mg/dL (serum glucose 110 mg/dL), and acid-fast bacilli are demonstrated on Ziehl-Neelsen staining. What is the most appropriate next step in management?