A ten-year experience with fiberoptic bronchoscopy for mycobacterial isolation. Impact of the Bactec system

From January 1974 to December 1983, positive mycobacterial isolates from all sources were reviewed to determine the impact of fiberoptic bronchoscopy (FB) on retrieval and identification of these organisms. There were 112 patients with positive cultures obtained during FB, 25 with Mycobacterium tuberculosis and 87 with mycobacteria other than tuberculosis (MOTT). We reviewed the results of prebronchoscopy and postbronchoscopy sputum specimens, bronchial washings, brushings, and transbronchial biopsy to determine the yield from each specimen in patients with M. tuberculosis. The bronchial washings provided positive cultures in 24 of 25 and were exclusively positive in 10 of 25 (40%). We also reviewed the clinical presentation, chest roentgenogram, bronchoscopy findings, and culture data for the 87 patients with MOTT isolated. The isolation of MOTT from bronchoscopy specimens increased throughout the study, most notably with the introduction of a rapid radiometric method (the Bactec system) for the recovery of mycobacteria to our laboratory in June 1983. Active disease could be established in only 13 of 87 cases (15%). Our findings confirm the sensitivity of Bactec in the isolation of MOTT from bronchoscopic specimens. The Bactec system, on the other hand, does not differentiate saprophytic colonization from clinical disease. To avoid expensive, time-consuming biochemical identification necessary to evaluate these MOTT isolates, careful selection of patients prior to obtaining mycobacterial cultures during FB is a critical factor.