Factors that affect sputum conversion and treatment outcome in patients with Mycobacterium avium-intracellulare complex pulmonary disease

To investigate factors that might affect the sputum conversion and treatment outcome of Mycobacterium avium-intracellulare complex (MAC) pulmonary disease.

This retrospective study reviewed 46 patients diagnosed with MAC pulmonary disease at the Chang Gung Memorial Hospital at Linkou between July 1998 and February 2005. The diagnosis was based on the American Thoracic Society criteria for diagnosis of disease due to non-tuberculous mycobacteria of 1997.

Of the 46 patients reviewed, 30 were men and 16 women, with a mean age of 64.39 years (range, 28-87 years). Thirty one patients had preexisting lung diseases, including history of pulmonary tuberculosis in 23 patients. Follow-up of sputum cultures could be traced in 28 patients, and sputum conversion was found in 17 patients. Of the 28 patients, 9 were treated with anti-MAC drugs for <5 months or with a regimen not containing at least 2 anti-MAC drugs. These treatment regimens were significantly associated with failure of sputum conversion to culture negativity (adjusted odds ratio [OR], 16.83; 95% confidence interval [CI], 1.16-245.06; p=0.039). Eleven of the remaining 19 patients were treated with an anti-MAC regimen containing clarithromycin for >5 months. However, there was no statistically significant association between sputum conversion and clarithromycin-containing anti-MAC regimens (OR, 0.42; 95% CI, 0.08-2.16; p=0.435).

MAC pulmonary disease often occurs in the context of preexisting lung disease, especially pulmonary tuberculosis. Patients tend to be older. Inappropriate treatment might lead to failure of sputum conversion. Treatment with rational combination regimens for at least 5 months could be necessary for sputum conversion.