Clinical Analysis of Pulmonary Nontuberculous Mycobacterial Disease Diagnosed as Coincidental Pulmonary Infection Due to Mycobacterium Species*

Objectives: We analyzed the clinical characteristics of patients with pulmonary mycobacterial disease diagnosed as coincidental pulmonary infection due to Mycobacterium species. Materials and Methods: One hundred sixty patients satisfied the diagnostic criteria of nontuberculous mycobacterial disease proposed by American Thoracic Society during the last seven years. Six patients (3.8%) were coincidental pulmonary infection due to two Mycobacterium species. We investigated the background, laboratory findings, microbiological findings, radiological findings, treatment and prognosis. Results: There were six patients, 3 males and 3 females, with a mean age of 71.7 years. The causative microorganisms of coincidental pulmonary infection consisted of Mycobacterium avium + Mycobacterium intracellulare in two patients, Mycobacterium avium + Mycobacterium kansasii in one, Mycobacterium intracellulare + Mycobacterium chelonae in one, Mycobacterium intracellulare + Mycobacterium abscessus in one, and Mycobacterium intracellulare + Mycobacterium tuberculosis in one. Regarding the radiological findings, the distribution of the lesion was frequently shown in both the right middle and left lingula lobes, but the extent of the lesion was limited within the unilateral lung field. Centrilobular small nodules with bronchiectasis were recognized in all patients and cavities or infiltration shadows were recognized in half of them on chest computed tomography. A definite diagnosis was obtained by bronchoalveolar lavage fluid in four patients and expectorated sputum in two. Combined chemotherapy was performed for two patients and that for pulmonary tuberculosis in one. Conclusions: Coincidental pulmonary infection due to Mycobactterium species occurred at a low percentage. Although most patients were elderly with underlying disease and clinical features were compatible with pulmonary Mycobacterium avium complex disease, the prognosis was comparatively good with and without treatment.