Evaluation of three rapid assays for Mycobacterium tuberculosis complex detection in a comprehensive hospital from West China

• Our study indicates a moderate rapid diagnostic performance for TB in West China.
• Real-time PCR and MTD are reliable for diagnosis and more sensitive than AFB smear.
• Real-time PCR can be preferred for extra-pulmonary tuberculosis and rare samples.
• MTD can be proposed for respiratory specimen to confirm clinical diagnosis.
• Qualified sample and combined detection will improve diagnostic capacity for TB.

ObjectivesTo assess the capacity of rapid and accurate confirmation of the Mycobacterium tuberculosis complex (MTBC) in a Chinese clinical laboratory.Design and methodsThis prospective study investigated three rapid assays, the Amplified Mycobacterium Tuberculosis Direct (MTD) test, real-time PCR, and acid-fast bacilli (AFB) smear, for direct detection of MTBC in a large consecutive series of different clinical specimens. Performance parameters were estimated and compared overall and for separate specimen categories using a combined reference gold standard.ResultsThe overall sensitivities were similar for MTD and real-time PCR (62.26% vs. 58.49%), significantly higher than those of AFB smear (31.13%). Among three assays, MTD had a satisfactory sensitivity in respiratory specimen (73.33%) and a nearly perfect detection for smear-positive samples (96.97%). Real-time PCR showed a high positive rate (58.97%) in regard to nonrespiratory specimen. A combination of molecular assays with conventional methods reached marked additive diagnostic values (sensitivity up to 76.42%), higher than each method individually. All detection systems showed excellent specificities (> 96.00%).ConclusionsThe present study indicated that our lab had a moderate diagnostic performance for tuberculosis. Quality guarantee for specimen pretreatment, as well as combination analysis, will enable these assays to better incorporate into the routine laboratory workflow in China.