To determine the demographic, behavioral, clinical, and geographic risk factors associated with the occurrence of multidrug-resistant pulmonary tuberculosis (MDRTB). To evaluate the clinical and microbiological responses and overall survival of MDRTB patients who are treated with levofloxacin-containing multiple-drug regimens chosen from a hierarchical list. Per 9/28/94 amendment, to assess whether persistent or recurrent positive sputum cultures of patients who show failure or relapse are due to the same strain or reinfection with a new strain.