A Pilot Study of Methodology to Rapidly Evaluate Drugs for Bactericidal Activity, Tolerance, and Pharmacokinetics in the Treatment of Pulmonary Tuberculosis Using Isoniazid and Levofloxacin

Inclusion Criteria Concurrent Medication: Allowed in all patients: * Antacids if administered more than 2 hours before or after study drug. Allowed in isoniazid patients: * Anticonvulsant therapy if blood levels are monitored. Allowed in levofloxacin patients: * Acceptable medications other than antacids if administered at least 2 hours before or 1 hour after study drug. * Anticonvulsant therapy, theophylline, or warfarin if doses are monitored. Patients must have: * Presumptive active pulmonary TB. * No clinical evidence of central nervous system or miliary tuberculosis. NOTE: * Both HIV-positive and HIV-negative patients are eligible. NOTE: * Pregnant women may be enrolled in the isoniazid cohort only. Exclusion Criteria Co-existing Condition: Patients with the following symptoms or conditions are excluded: * Active or suspected MAI infection. * Active or suspected hepatitis. * Any other serious acute infection, diabetes, chronic obstructive pulmonary disease, malignancy requiring chemotherapy, or major organ dysfunction. * Extreme illness or toxic appearance. * Pregnancy (if entering the levofloxacin portion of the study). Concurrent Medication: Excluded: * All standard TB therapies. * Clofazimine. * Rifabutin. * Quinolones. * Aminoglycosides. * Corticosteroids. * Pentoxifylline. * Colony-stimulating factors. * Interferons. * Interleukins. * Disulfiram (patients receiving isoniazid). Patients with the following prior conditions are excluded: * History of treatment-limiting intolerance or known hypersensitivity to isoniazid (in patients receiving isoniazid) or to quinolones (in patients receiving levofloxacin). * Vomiting or diarrhea \>= grade 2 at screening or within 2 days prior to screening. * History of drug-resistant TB (in patients receiving isoniazid). Prior Medication: Excluded: * Any prior treatment or prophylaxis for TB if enrolling on the isoniazid cohort. * Any anti-TB drug within the past 12 weeks, including standard drugs against TB as well as clofazimine, rifabutin, and all quinolones and aminoglycosides. * Corticosteroids, pentoxifylline, colony-stimulating factors, interferons, or interleukins within the past 12 weeks. Known risk factors for multi-drug resistant (MDR) TB, including: * Domicile, shelter, or prison exposure to a known case of MDR TB within the past 6 months. * Residence in a specific domicile, shelter, or prison cell block within 6 months of a known outbreak of MDR TB. * Hospitalization, within the past 6 months, on a medical service or unit in which nosocomial transmission of MDR TB is known to have occurred.