Comparison of Two Molecular Methods for Rapid Diagnosis of Tuberculosis

Tuberculosis remains a global prevalent infectious disease and a serious public-health problem in Taiwan. This study was purposed to evaluate the performance of identifying Mycobacterium tuberculosis complex (MTBC) by following two methods: Roche COBAS TaqMan MTB Test (COBAS assay) which is a real-time PCR-based kit, and MP FASTSURE TB DNA Rapid Test (MP assay) which uses the cross-priming amplification technology for the qualitative detection of MTBC DNA. We collect 210 clinical samples to assess the performance of these two methods between January and December 2011. The results obtained were compared with those from conventional methods. The sensitivity, specificity, and positive/negative predictive values (PPV/NPV) of MP assay for 144 routine clinical specimens were 92.75%, 98.67%, 98.46%, and 93.67%, respectively; and those were 91.30%, 89.33%, 100%, 93.06% for COBAS assay. The sensitivity, specificity, PPV and NPV of MP assay for 50 positive BACTEC MGIT 960 cultures give satisfying outcomes (100%, 100%, 100% and 100%, respectively) ; and those were 100%, 52.94%, 100%, 100% for COBAS assay. Furthermore, the sensitivity, specificity, PPV and NPV of MP assay for 16 positive Löwenstein-Jensen cultures give satisfying outcomes (100%, 100%, 100% and 100%, respectively) ; and those were 50%, 16.67%, 100%, 100% for COBAS assay. Finally, the sensitivity and specificity of MP assay for total 210 samples were 95.28% and 99.04%, respectively; and those were 92.45%, 75% for COBAS assay. Nevertheless, results also indicate that both working time and cost required for MP assay were more effective than COBAS assay. MP assay could be considered as an alternative to currently available identification methods.