Abstract
Tuberculosis (TB) and the spread of Mycobacterium tuberculosis complex (MTBC) strains resistant against rifampin (RIF) and isoniazid (INH) pose a serious threat to global health. However, rapid and reliable MTBC detection along with RIF/INH susceptibility testing are challenging in low prevalence countries due to the higher rate of false positives. Here, we provide the first performance data for the artus MTBC PCR assay in a low prevalence setting. We analyze 1323 respiratory and 311 non-respiratory samples with the artus MTBC PCR assay as well as by mycobacterial culture and microscopy. We propose retesting of specimens in duplicate and consideration of a determined cycle-threshold value cut-off greater than 34, as this significantly increases accuracy, specificity, and negative predictive value without affecting sensitivity. Furthermore, we tested fourteen MTBC positive samples with the GenoType MTBDRplus test and demonstrate that using an identical DNA extraction protocol for both assays does not impair downstream genotypic testing for RIF and INH susceptibility. In conclusion, our procedure optimizes the use of the artus MTB assay with workload efficient methods in a low incidence setting. Combining the modified artus MTB with the GenoType MTBDRplus assays allows rapid and accurate detection of MTBC and RIF/INH resistance.
Highlights
Tuberculosis (TB) and the spread of Mycobacterium tuberculosis complex (MTBC) strains resistant against rifampin (RIF) and isoniazid (INH) pose a serious threat to global health
We note that analyses from multiple samples from the same patient raises the chance of finding MTBC, but the focus of this work was on a technical validation of the artus MTB assay and not on TB
PCR-based molecular assays have become a mainstay for the rapid detection and identification of MTB complex organisms in clinical specimens
Summary
Tuberculosis (TB) and the spread of Mycobacterium tuberculosis complex (MTBC) strains resistant against rifampin (RIF) and isoniazid (INH) pose a serious threat to global health. Rapid and reliable MTBC detection along with RIF/INH susceptibility testing are challenging in low prevalence countries due to the higher rate of false positives. It combines in a cartridge system DNA extraction from the clinical sample with molecular detection of MTB complex and resistance testing against the first line anti-TB drug rifampin (RIF), and it is suitable for point-of-care use when laboratory resources are limited otherwise. The GX assay completely ignores isoniazid (INH) resistance, which is found in 5% to 15% of RIF-susceptible cases worldwide and has a significant impact on treatment outcome[14,15] It is not suited for the timely detection of multidrug-resistant (MDR) MTB strains[16], defined as resistance toward RIF and INH. PCR assay for the detection of all members of the tuberculosis complex using the Rotor-Gene Q
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