Comparison of real-time PCR and conventional PCR assay using IS6110 region of Mycobacterium tuberculosis for efficient diagnosis of tuberculous meningitis and pulmonary tuberculosis

The present study was aimed at evaluating the role of a real-time polymerase chain reaction (RT-PCR) assay in the diagnosis of tuberculous meningitis (TBM) and pulmonary tuberculosis (PTB) and comparison of its performance with the in-house conventional PCR (C-PCR) assay. A RT-PCR assay using SYBR green methodology and C-PCR targeting a segment of the gene for mycobacterial IS6110 region were evaluated in 109 clinical samples consisting of 59 cerebrospinal fluid (CSF) samples and 50 sputum samples for diagnosis of tuberculosis (TB). When compared with the findings of clinical observations, the sensitivity and specificity of RT-PCR in detecting TBM was 87.5 and 88.5%, respectively and that of C-PCR assay was 79.1 and 88.5%, respectively in the same set of CSF samples. For detecting PTB, sensitivity and specificity of RT-PCR was 91.7 and 84.6% and C-PCR assays was 77 and 92.8%, respectively in sputum samples. The overall accuracy of the RT-PCR assay was higher compared with that of the C-PCR assay. Additionally, the RT-PCR has the advantage of a short experimental time, low risk of sample contamination, and offers the possibility to quantify bacterial load, making it a powerful tool for the rapid diagnosis of TBM and PTB.