Molecular assays for the initial diagnosis of tuberculosis in a low-prevalence setting: A comparative study

The WHO's End TB Strategy promotes using rapid molecular assays as initial diagnosis to reduce tuberculosis globally. This prospective study assessed commercial molecular platforms' effectiveness in diagnosing or ruling out tuberculosis (TB) in a low-prevalence setting.

One hundred clinical samples (80 respiratory/20 non-respiratory) were included among all samples routinely received in a mycobacterial laboratory. Five real-time polymerase-chain-reaction (RT-PCR) assays (Xpert-MTB/Rif-Ultra, BDMAX-MDR-TB, RealTime-MTB, FluoroType-MTBDR, Anyplex-MTB/NTM) were characterized and compared through blinded-parallel analysis. Sensitivity, specificity, likelihood ratios, and Cohen's Kappa were calculated to assess the accuracy and agreement of RT-PCR results with culture.

Sensitivity ranged 88.89-100%, improving initial screening by 30-40%. Specificity was 96.70-98.98%. RT-PCR showed excellent discriminatory power, as TB patients were 26.9-91.0 times more likely to test positive. Cohen's Kappa showed substantial to excellent concordance (0.78-0.94).

RT-PCR improves TB initial diagnosis, offering tailored solutions for diverse laboratories, revolutionizing control strategies with its operational flexibility.