[A case of pulmonary infection caused by Mycobacterium szulgai]

We report a case of pulmonary non-tuberculous mycobacteriosis caused by Mycobacterium szulgai. A thirty-nine-year-old man with no relevant significant past history underwent an annual medical check. His chest X-ray and CT scan showed an infiltrative shadow with a cavity in the right upper lobe. As it was suggestive of pulmonary tuberculosis, he was referred to our hospital. Smear tests of his sputum, gastric fluid, and transbronchial fluid showed no mycobacterial organisms, but culture of the samples revealed growth of mycobacteria. The organism was identified as M. szulgai using a DNA-DNA hybridization method, and the case was diagnosed as pulmonary non-tuberculous mycobacteriosis caused by M. szulgai. By anti-mycobacterial drug treatment with isoniazid, rifampicin, and ethambutol, the infiltrative shadow on chest roentogenogram and CT showed improvement. Culture of his sputum and gastric fluid showed no growth of mycobacteria after starting treatment.