Objective To evaluate the clinical application value of two immunochromatogaphic assay kits Mycobacterium tuberculosis complex identification kit (MGIT TBc ID test) and Mycobacterium tuberculosis antigen assay kit (Capilia TB assay) for rapid identification of Mycobacterium tuberculosis complex (MTBC) in Mycobacteria testing system (BACTEC MGIT 960 System) positive cultures.
Methods Reference mycobacterial strains (n=15) and BACTEC MGIT 960 System positive culture samples (n=418) were collected to apply two immunochromatogaphic assay kits and traditional biochemical method to identify MTBC and nontuberculous mycobacteria. Inconsistent identification results were confirmed by 16S rRNA gene sequencing.
Results The traditional biochemical method was used as the gold standard. The sensitivity, specificity, positive predictive value, and negative predictive value of Capilia TB assay for MTBC detection were 98.4% (253/257), 99.4% (160/161), 99.6% (253/254), and 97.6% (160/164), respectively; those of MGIT TBc ID test were 98.4% (253/257), 100% (161/161), 100% (253/253), and 97.6% (161/165), respectively. Compared with the traditional biochemical method, the Kappa values of Capilia TB assay and MGIT TBc ID test were 0.975 and 0.980 respectively, indicating good consistency. The results of 16S rRNA gene sequencing for inconsistent strains were 4 strains of MTBC and 1 strain of Nocardia.
Conclusion The Capilia TB assay represents a rapid, simple MT identification test that could be used to BACTEC MGIT 960 System positive cultures in clinical laboratories. The MGIT TBc ID test is more accurate and could be used in public health emergencies.
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