Real-time PCR and Amplified MTD® for rapid detection of Mycobacterium tuberculosis in pulmonary specimens

Patients with suspected pulmonary tuberculosis (PTB) in the First Affiliated Hospital, College of Medicine, Zhejiang University.

To evaluate the 'Care TB®' real-time polymerase chain reaction (PCR) assay in comparison with the Amplified MTD® Test (AMTD) for the rapid diagnosis of TB.

Self-expectorated sputum was collected for direct smear microscopy, culture, real-time PCR and AMTD assay. Performance of the 'Care TB' real-time PCR and AMTD assay were compared using a combination of culture and clinical diagnosis as a reference standard.

Of the 178 sputum specimens, 83 were culture-positive; of these, 74 were Mycobacterium tuberculosis complex and 9 strains were non-tuberculous mycobacteria. The overall sensitivities and specificities were respectively 91.6% and 100% for real-time PCR, and 95.2% and 97.9% for AMTD. In the smear-positive specimens, the sensitivities and specificities were respectively 97% and 100% for real-time PCR, and 98.5% and 100% for AMTD. In the smear-negative specimens, the sensitivities and specificities were 70.6% and 100% for real-time PCR, and 82.4% and 97.7% for AMTD.

Both real-time PCR and AMTD are rapid and specific tests for detecting M. tuberculosis complex; however, 'Care TB' real-time PCR is more convenient and economical.