Sensitive identification of mycobacterial species using PCR-RFLP on bronchial washings

In 98 patients (24 with active pulmonary tuberculosis [TB] lesions, 28 with cured TB lesions, and 46 with nontuberculous opacities [control group] in chest CT scans), we examined whether washing the bronchus after brushing th e lesion, then applying polymerase chain reaction-restriction fragment leng th polymorphism (PCR-RFLP) to the bronchial washings might be useful for di agnosing TB and nontuberculous mycobacteriosis (NTMosis). After biopsy and brushing with a bronchoscope, the bronchus connecting to the lesion was was hed with 20 ml saline. The saline used for washing the brushes (5 ml; brush ing sample), and 3 to 10 ml saline aspirated through the forceps channel (w ashing sample) were examined by PCR-RFLP, which proved able to identify Myc obacterium tuberculosis and seven species of nontuberculous mycobacteria (N TM). The values obtained for the sensitivity of the PCR-RFLP with respect t o the brushing sample, the washing sample, and both samples mixed together were 70, 76, and 91%, respectively, when only patients who were culture-pos itive or radiologically improved after antituberculous therapy were conside red as showing true infection, A mixture of brushing and washing samples pr ovides useful material for PCR and culture, and the PCR-RFLP used here is a good method for the simultaneous identification of several species of myco bacterium (including M. tuberculosis).