Nontuberculous mycobacterial lung disease. Substantiation of a less aggressive approach.

A nonsurgical, less aggressive, less toxic chemotherapeutic protocol for the management of nontuberculous mycobacterial (NTB) pulmonary infections has been uniformly applied to patients in our institution between 1972 and 1985. Forty-three nonimmunocompromised patients with active lung disease caused by Mycobacterium avium-intracellulare (MAI) (n = 26), M kansasii (n = 16), and M xenopi (n = 1) were identified retrospectively. Eighteen MAI patients were treated with three or four antituberculosis agents resulting in sputum conversion and clinical improvement in 12 (67 percent). Additionally, 11 out of 16 (69 percent) patients completing therapy or still undergoing therapy for persistent MAI disease, achieved sputum conversion and clinical improvement after prolonged therapy (3.6 +/- 0.5 years [SEM]). When M kansasii was identified as the etiologic agent, all patients were treated with four or fewer antituberculosis agents and 14 out of 16 patients (88 percent) achieved sputum conversion and clinical improvement throughout the follow-up period. We conclude that the use of three or four chemotherapeutic agents in the treatment of NTM lung disease provides an excellent probability of successful outcome even in MAI infections.