Mixed pulmonary infection with three types of nontuberculous mycobacteria.

A 71-year-old man with a history of chronic obstructive pulmonary disease (COPD) and silicosis was referred to our hospital for an evaluation of dyspnea. A progressively enlarging cavity found in the patient's left lower lung was associated with a worsening respiratory status. One year after the initial referral, the patient was diagnosed with nontuberculous mycobacterial (NTM) infection. We herein report the case of a patient with a mixed infection of M. kansasii, M. avium complex and M. abscessus, the various organisms having been isolated in succession. Recognizing a diagnosis of mixed pulmonary NTM infection is therefore crucial in patients with underlying diseases.