Persistence of Mycobacterium tuberculosis in sputum without chest roentgenographic evidence of active disease.

Mycobacterium tuberculosis has been isolated consistently from sputum over an 11-year period in an asymptomatic 64-year-old man whose chest radiographs show evidence of healed primary tuberculosis (Ranke complex) but no evidence of parenchymal disease. A lymph node-bronchial fistula associated with the Ranke complex is the likely site of active tuberculosis; however, repeated examinations of the upper and lower respiratory tract have been normal. We attribute the persistence of infection in our patient to erratic usage of antituberculous drugs.