Bronchopulmonary infection with Mycobacterium malmoense presenting as a bronchoesophageal fistula

We report a bronchopulmonary infection with Mycobacterium malmoense in a patient with severe immunosuppression due to insulin-dependent diabetes mellitus, humoral immunodeficiency after thymoma (Good's syndrome) and prolonged immunosuppressive treatment after myasthenic crisis. It presented as non-resolving pneumonia of the left lower lobe. Bronchoscopically, a bronchoesophageal fistula was detected. Numerous acid-fast organisms were found in the sputum specimen and in the bronchial biopsy around the fistula. M. malmoense was isolated from sputum, bronchoalveolar lavage and bronchial biopsy. Whereas conventional in vitro susceptibility testing revealed susceptibility only to ethambutol, multi-drug susceptibility testing confirmed susceptibility to rifampicin, ethambutol, clarithromycin and prothionamide. The clinical outcome after 12 months of therapy resulted in a stable remission and considerable suppression of the mycobacterial load, but not in complete eradication.