Quantitative detection of a cocktail of mycobacterial MPT64 and PstS1 in tuberculosis patients by real-time immuno-PCR.

Abstract

There is an urgent need to design a reliable diagnostic test for tuberculosis (TB). Real-time immuno-PCR (RT-I-PCR) assay was devised for the quantitative detection of a cocktail of mycobacterial MPT64 (Rv1980c) and PstS1 (Rv0934) in TB patients. A broad dynamic range of 0.95pg/ml-95ng/ml of MPT64+PstS1 was detected in TB patients. In smear-positive (n=59) and smear-negative (n=42) pulmonary TB cases, sensitivities of 93.2 and 83.3% were observed, respectively with 92.8% specificity, whereas a sensitivity of 77.9% and a specificity of 91.3% were observed in extrapulmonary TB cases (n=86). Furthermore, significantly reduced MPT64+PstS1 concentrations (p <0.001) were noticed in patients on therapy by RT-I-PCR as compared with untreated patients. Our RT-I-PCR assay revealed high sensitivity especially for the rapid diagnosis of smear-negative pulmonary TB and paucibacillary extrapulmonary TB samples, which could also monitor the dynamics of disease in patients on therapy.