A 42-year-old woman with rheumatoid arthritis treated with methotrexate presents to the hospital with a 3-week history of productive cough, fever (38.5°C), and progressive dyspnea. She denies night sweats, hemoptysis, or recent travel. Vital signs include HR 102/min, BP 130/84 mmHg, RR 20/min, and SpO2 92% on room air. Physical examination reveals right upper lobe consolidation on percussion. Chest X-ray shows a solitary cavitary lesion in the right upper lobe. Laboratory studies reveal WBC 7,200/μL, hemoglobin 11.2 g/dL, and mild hyponatremia (Na+ 128 mEq/L). Tuberculin skin test shows 10 mm induration. Three sputum acid-fast bacillus (AFB) smears are negative. Blood cultures and sputum culture for routine bacteria are pending. Which of the following is the most appropriate next step in management?

1. A)Obtain high-resolution CT chest and perform bronchoscopy with bronchoalveolar lavage for AFB culture and mycobacterial PCR
2. B)Initiate antituberculous therapy (isoniazid, rifampin, pyrazinamide, ethambutol) while awaiting sputum culture resultsGABARITO
3. C)Start empiric broad-spectrum antibiotics (fluoroquinolone) and discontinue methotrexate; reassess in 1 week
4. D)Perform repeat tuberculin skin test with 2-step testing and defer treatment until conversion is documented
5. E)Administer high-dose corticosteroids to reduce inflammation and obtain repeat chest X-ray in 48 hours