Mycobacterium xenopi infection masquerading as pulmonary tuberculosis in two patients infected with the human...

Mycobacterium xenopi infections have rarely been reported among patients infected with the human immunodeficiency virus (HIV). We recently treated two HIV-infected men, neither of whom had a history of pulmonary disease or AIDS-defining conditions, and who had M. xenopi lung infections. Both patients presented with night sweats, cough, and pleuritic chest pain. Chest radiographs showed an upper-lobe nodule in the first patient and a perihilar cavitary infiltrate in the second patient. Both patients were initially believed to have pulmonary tuberculosis and were treated accordingly; however, only M. xenopi grew on cultures of multiple respiratory specimens. This diagnosis was confirmed by cultures of biopsied lung tissue from the first patient and of fluid from a peritracheal abscess in the second patient. Both patients' clinical conditions improved after multidrug therapy (isoniazid, rifampin, pyrazinamide, ethambutol, and ciprofloxacin in the first case; isoniazid, rifampin, and pyrazinamide in the second case). The second patient's condition improved despite in vitro resistance of his isolate to isoniazid and rifampin.