Mycobacterium europaeum lung disease in an immunocompetent patient without underlying lung disease

Mycobacterium europaeum (M. europaeum) was recently identified as a nontuberculous mycobacterium belonging to the Mycobacterium simiae complex. There have been only a few reported cases of M. europaeum lung disease, all of which occurred in patients with immunodeficiency or prior lung disease. We herein report a case of M. europaeum lung disease in an otherwise healthy Japanese individual. A 70-year-old woman who had no apparent immunodeficiency or medical history was diagnosed with M. europaeum lung disease by multiple positive sputum cultures. The patient was successfully treated with clarithromycin, rifampin, ethambutol, and amikacin. This report is the first case of M. europaeum lung disease occurring in an individual without predisposing risk factors.