Thank you for the recent comments
1 for the topic of real-time polymerase chain reaction (RT-PCR) assay
2. We propose that positivity in RT-PCR using any respiratory specimens suggests the possibility of active tuberculosis (TB) in clinically suspected cases, guiding to start anti-TB medication, and RT-PCR from selective bronchoscopic aspirates enhances the diagnostic yield much more when added to sputum examination
2. Wiwanitkit
1 mentioned that "There are some concerns on this assay. False-positive of the test can be seen in cases with treated or old lesion from pulmonary TB and the low sensitivity of the test can be seen."
As a response to the issues of false-positivity raised by Wiwanitkit
1, it was mentioned in our paper
2 that "In our study, the false-positive rate was 0.5% in sputum and 2.0% in bronchoscopic aspirates. False-positivity in PCR has been reported to be due to carry-over contamination between specimens, cross-reactions with isolated nontuberculous mycobacteria, or dead tissue debris from previous TB scarring in highly endemic areas."
Low sensitivity of this test was also discussed in our paper
2 that "Most reports have evaluated PCR using known acid-fast bacilli-positive samples. In smear-positive specimens, the sensitivity and specificity of polymerase chain reaction are in the range 90%-100%, with a positive predictive value of >95%, whereas in smear-negative specimens, the sensitivity of PCR is reduced to <50%. In this study, the sensitivity of RT-PCR in acid-fast bacilli smear-positive specimen was observed 89%. Factors that affect RT-PCR sensitivity include the individual effort expended for sputum collection and clinician bias with regard to diagnostic approaches."