An initial cohort of patients receive isoniazid (with pyridoxine) daily for 5 days. Sputum samples are collected daily for determination of the EBA (decline in colony-forming units/ml sputum). If the methodology is validated, additional patients are randomized to receive one of two doses of levofloxacin daily for 5 days, with determination of EBA. All patients are hospitalized for 2 days of baseline evaluation and 5 days of treatment.