Sensitivity and Specificity of Acid Fast Bacilli Smear from Induced Sputum and Bronchoalveolar Lavage (BAL) in Diagnosis of Negative Acid Fast Bacilli Tuberculosis


Eva Sri Diana, Wiwien Heru Wiyono, Boedi Swidarmoko, Arifin Nawas

Background : Some cases of pulmonary tuberculosis (PTB) cases that are being treated in our country are with negative acid fast bacilli (AFB sputum smear and culture). Acid fast bacilli (AFB) microscopy and conventional Lowenstein Jensen (LJ) culture from sputum remain the cornerstone for the diagnosis of TB but the sensitivity of these traditional methods is quite low. There is need for rapid, sensitive and accurate detection of these organism in clinical specimens to hasten the administration of appropriate antimycobacterial therapy and prevent the spread of infection in the community. Samples from sputum induction and/or bronchoalveolar lavage might be helpful in the diagnosis of SSN-PTB. The aims of this study is to evaluate whether sample collection by BAL yields a higher positive rate compare to sputum induction in diagnosis PTB in negative AFB smear cases, and whether collection by BAL combined with sputum induction would give a higher positive rate in diagnosing PTB in negative AFB smear cases.
Methods : In descriptive analytic study, we have collected data consecutively from sputum smear-negative pulmonary tuberculosis patients between Januari 2010 and April 2010. Acid fast bacilli sputum from 33 samples were collected using sputum induction technique and then followed by BALfluid collection on the next day. All samples were sent to laboratory for smear and culture.
Results : Bronchoalveolar lavage collected samples had highest positive rate (85%) followed by smears from BAL collected samples (45%). Acid fast bacilli culture from sputum induction and spontaneous sputum were equal (36%). Smears of sputum induction samples had the lowest positive rate (6%).
Conclusion : Acid fast bacilli examination of sample obtained from BAL had a significantly higher positive rate compare to sputum induction. Sputum culture had a significantly better positive rate compare to sputum induction, and AFB smears from BAL samples had equal positive rate with sputum culture. (J Respir Indo. 2013; 33:82-91)

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