Use of Clarithromycin and Rifabutin for the Treatment of M. Avium Complex (MAC) Lung Disease

Inclusion Criteria: * Meet American Thoracic Society criteria for nontuberculous mycobacterial lung disease: two or more AFB smear positive, culture positive sputums or bronchoscopic samples and/or two or more AFB smear negative respiratory samples with moderate to heavy growth (2+-4+); abnormal CXR consistent with M. avium lung disease; absence of other potential mycobacterial or fungal lung pathogens (except for the coexistence of M. abscessus). * Adults age 18 and older * Pretreatment isolate of M. avium complex available for MIC determination Exclusion Criteria: * History of allergy to study drugs * If a mensruating female, not pregnant and on adequate birth control. * Children less than 18 years of age * HIV + or at high risk for HIV infection.