The primary objective of this Phase 2 clinical trial is to compare the safety and antimicrobial activity of a moxifloxacin-containing regimen (moxifloxacin, rifampin, pyrazinamide, ethambutol [MRZE]) in which moxifloxacin has been substituted for isoniazid, to the standard control regimen (isoniazid, rifampin, pyrazinamide, ethambutol [HRZE]) in the first two months of treatment of sputum smear-positive pulmonary tuberculosis. The assessment of antimicrobial activity will be sputum culture-conversion. Higher rates of sputum culture conversion after 2 months of treatment with a moxifloxacin-containing regimen would support Phase 3 clinical trials of moxifloxacin in treatment regimens of less than the current 6 month standard regimens.