Abstract
Background: Accurate differentiation between Mycobacterium tuberculosis (MTB) and nontuberculous mycobacteria (NTM) is essential for proper diagnosis and treatment. This study compares the diagnostic performance of two commercial real-time PCR kits, AdvanSure(TM) TB/NTM and Kogene PowerChek(TM) MTB/NTM, for detecting MTB, NTM, and negative (no growth, NG) clinical specimens. Methods: A total of 390 clinical residual specimens were collected from patients between December 2022 and June 2023. The samples, including sputum, bronchoalveolar lavage, tracheal aspirate and body fluid, were initially tested with MGIT culture and then analyzed using both PCR kits. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy were evaluated. Discrepant results between the two PCR assays were further investigated using sequencing to identify the detected mycobacterial species, and final diagnoses were verified by culture results and review of electronic medical records. Results: Of the 390 specimens, both AdvanSure(TM) and PowerChek(TM) real-time PCR assays demonstrated 100% sensitivity for both MTB and NTM detection. For MTB detection, AdvanSure(TM) demonstrated a specificity of 100%, with a PPV, NPV, and overall accuracy all reaching 100%. In comparison, PowerChek(TM) showed a specificity of 98.62%, a PPV of 96.15%, an NPV of 100%, and an overall accuracy of 98.97%. For NTM detection, both AdvanSure(TM) and PowerChek(TM) exhibited identical performance metrics. The specificity was 99.58% for both assays, with a PPV of 99.34%, NPV of 100%, and an overall accuracy of 99.74%. Five discrepant results were finally confirmed as four NTM detection cases and one negative case by culture and clinical diagnosis which showed four cases of PowerChek(TM) MTB+NTM detection and one case of NTM detection, respectively. Conclusions: The PowerChek(TM) MTB/NTM real-time PCR kit demonstrated excellent diagnostic performance for the detection of MTB and NTM, with high sensitivity, specificity, and accuracy. Minor discrepancies, particularly in detecting MTB+NTM mixed infections, highlight the importance of complementary sequencing analysis for resolving uncertain results. These findings support the clinical utility of both PCR assays as reliable tools for rapid diagnosis of mycobacterial infections. PowerChek(TM) showed occasional false positives, suggesting that optimizing the assay's cutoff threshold or amplification parameters could enhance its specificity and reduce false-positive results in clinically ambiguous cases.