The impact of nontuberculous mycobacteria on management of presumed pulmonary tuberculosis

Background: The presence of nontuberculous mycobacteria (NTM) in sputum or bronchial washings may cause diagnostic problems which affect clinical mana gement. Patients and Methods: In a retrospective analysis of 135 patients in a Dutc h tuberculosis center, patients with NTM isolates were thoroughly investiga ted. Colonization or contamination by NTM was differentiated from true Lung disease. Results: 25 HIV-seronegative and two HIV-seropositive patients with NTM wer e identified. NTM were a likely cause of disease in only 14 (52%) patients. In 15 (55%), their presence Led to preliminary diagnosis and treatment of tuberculosis. Unnecessary or inappropriate treatment was instituted in 17 ( 63%) patients with NTM. In two patients, detection of NTM in sputum also Le d to delay in diagnosing malignant disease. Conclusion: In this series, NTM in sputum or bronchial washings poorly refl ected disease and often Led to diagnostic and therapeutic errors. Although it is common knowledge that the presence of NTM should be considered in sme ar-positive patients, this apparently is a diagnostic pitfall in clinical p ractice. Reliable DNA-based techniques and better communication between phy sicians and microbiologists may improve management of suspected mycobacteri al infections.