Abstract:

Objective: To preliminarily evaluate the performance of the Genewise-MTBC system for the Mycobacterium tuberculosis complex detection. Methods: Serially diluted type strains of M.tuberculosis and M.bovis were used to identify the limit of detection (LOD) of Genewise-MTBC. A total of 17 strains of nontuberculous mycobacteria (NTM) and 14 other pathogenic microorganisms were included to test its specificity. Meanwhile, potential interfering substances at their highest physiological concentrations were mixed with sputum to test the anti-interference ability of the system. Moreover, based on clinical diagnosis, Genewise-MTBC tests were performed on 71 clinical specimens in parallel with GeneXpert MTB/RIF assay to evaluate the clinical feasibility. Results: The LOD of Genewise-MTBC was defined as 18 CFU/ml for MTBC detection. Meanwhile, the test had no cross-reactivity with 17 NTM and 14 other respiratory pathogens. With clinical diagnosis as the gold standard, for the 71 clinical specimens, the sensitivities of Genewise-MTBC and GeneXpert MTB/RIF were 61.11% (33/54) and 57.41% (31/54), respectively; the specificities were 94.12% (16/17) and 100.00% (17/17), respectively; the positive predictive values were 97.06% (33/34) and 100.00% (31/31), respectively; and the negative predictive values were 43.24% (16/37) and 43.50% (17/40), respectively. Conclusion: The Genewise-MTBC system possesses high sensitivity, specificity, stability and anti-interference capability, which is worthy of a large-scale clinical evaluation in the future.

Key words: Mycobacterium tuberculosis, Diagnosis, differential, Molecular diagnostic techniques