PURPOSE: Polymerase chain reaction (PCR) is the useful method for early detection of active tuberculosis. Real time PCR (RT-PCR) is known to have many advantages over conventional PCR. However, there is few data about the clinical utility of RT-PCR in bronchoalveoar lavage (BAL) fluid in Korea.
METHODS: From October 2008 to March 2010, we retrospectively evaluated the accuracy of RT-PCR in BAL fluid of the patients suspected of pulmonary Tb in chest CT with AFB smear-negative sputum or without sputum production. Active Tb was defined as the growth of mycobacterium tuberculosis in sputum expectorated after bronchoscopy or BAL fluid, or positive histological findings.
RESULTS: This study included 109 patients. Those unable to expectorate (57 patients, 52.4%) or producing sputum with two consecutive negative AFB smear (52 patients, 27.6%) underwent bronchoscopy. Fifty five(50.5%) patients were confirmed as active Tb. Diagnoses except for pulmonary Tb were as follows: pneumonia (n=21, 19.3%), NTM (n=13, 11.9%), interstitial lung diseases (n=13, 11.9%), lung cancer (n=3, 2.8%), old Tb (n=3, 2.8%), and undiagnosed cases (n=1, 0.9%). Overall, the sensitivity, specificity, positive and negative predictive values of RT-PCR in BAL fluid were 70.7%, 92.4%, 84.8% and 81.3%, respectively. They were 91.6.%, 80%, 95%, and 66.7% for AFB smear-positive BAL fluid, while 31.3%, 96%, 71.4%, and 80% for AFB smear- negative BAL fluid.
CONCLUSION: RT-PCR in BAL fluid has a moderate diagnostic yield. Particularly, it may have an additive benefit in an early diagnosis for the patients suspicious of pulmonary TB with AFB smear-negative in BAL fluid.
CLINICAL IMPLICATIONS: RT-PCR in BAL fluid is needed to make early diagnosis for the patients with AFB smear negative sputum or no sputum production.
DISCLOSURE: Soyoung Park, No Financial Disclosure Information; No Product/Research Disclosure Information