The Diagnostic Value of Bronchoalveolar lavage fluid microscopic study and PCR in Pulmonary tuberculosis

Park, Moon Hwan; Choi, Choon Han; Kim, Nam Jin

Abstract

BACKGROUND
We can diagnose pulmonary tuberculosis with sputum AFB smear and culture, but sputum AFB smear has low sensitivity and culture needs long period, and they are not available in the patients who can not expectorate effectively. Recently developed, PCR is a fast diagnostic tool in tuberculosis, but false positive and false negative are important problems. So, we studied the diagnostic value of bronchoalveolar lavage fluid AFB smear, culture, PCR through the bronchoscopy.
METHODS
The 67 pulmonary tuberculosis patients and 43 non-pulmonary tuberculosis patients were analyzed with their sputum specimen AFB smear and culture. Also, bronchoscopy and bronchoalveolar lavage were done, and bronchoalveolar lavage fluid AFB smear, culture and PCR were done.
RESULTS
1) In the cases of pulmonary tuberculosis, the sensitivity of sputum AFB smear and culture were 32.8% and 57.4%, respectively. And the sensitivity of bronchoalveolar lavage fluid AFB smear and culture were 47.8% and 80.6%. respectively. 2) In the cases of pulmonary tuberculosis, the sensitivity and the positive predictive value(for predicting a positive culture) of PCR were 80.6% and 81.5%, respectively. 3) In the cases of sputum AFB smear-negative and culture-negative pulmonary tuberculosis, the sensitivity of bronchoalveolar lavage fluid AFB smear, culture, PCR, and the positive predictive value(for predicting a positive culture) of PCR were 23.1%, 100%, 88.5%, and 82.4%, respectively. 4) The specificity of bronchoalveolar lavage fluid PCR was 77.0%. 5) The median number of days between obtaining a specimen and starting therapy was 5 days for sputum AFB smear, 9 days for bronchoalveolar lavage fluid AFB smear, 26 days for bronchoalveolar lavage fluid PCR, 32 days for sputum culture, 56 days for bronchoalveolar lavage fluid culture.
CONCLUSION
The sensitivity of bronchoalveolar lavage fluid AFB smear and culture are higher than sputum AFB smear and culture. So, the bronchoscopy must be considered for evaluating suspected cases of pulmonary tuberculosis in patients from whom smears of expectorated sputum do not reveal mycobacteria or from whom no sputum can be obtained. Especially, combined with PCR, it is expected that pulmonary tuberculosis can be diagnosed more rapidly and more accurately, so bronchoalveolar lavage fluid AFB smear and PCR can be helpful in the early treatment of pulmonary tuberculosis.