Abstract
Occasionally, mycobacterium is detected from bronchial lavage fluid (BLF) even in patients without any sign of pulmonary tuberculosis. In contrast, we sometimes experience BLF smear-positive culture-negative (SPCN) cases in these patients. To determine the significance of mycobacterium detection in BLF, we studied 75 smear or culture positive samples in the past four years at our hospital. We compared results between sputum and BLF examination in these cases. Atypical Mycobacterium (AM) was detected in 33% of BLF and in 7% of the sputum respectively. These results lead us to consider that AM caused BLF SPCN because its growth was limited in the culture medium. Therefore, we examined five BLF SPCN cases using three different media, common 3% Ogawa medium, 2% Ogawa medium and Ogawa K medium. No colony was found in any of the cases. We then cultured smear positive BLF using Ogawa medium without NaOH, which is toxic to particular AM strains. Mycobacterium was found in 63% of the cases compared to 36% when common Ogawa medium was used. More AM was confirmed from BLF when Ogawa medium without NaOH was used. From these results, we conclude that AM is more frequent than mycobacterium tuberculosis in SPCN BLF, and Ogawa medium without NaOH is useful for the detection of the atypical mycobacterium.
