Abstract
The MDR/MTB ELITe MGB® kit (ELITech) carried on the ELITe InGenius® platform is a new real-time PCR assay allowing automated extraction and detection of DNA of the Mycobacterium tuberculosis complex (MTB) and mutations in the rpoB and katG genes and inhA promoter region (pro-inhA) associated to resistance to rifampicin and isoniazid, the two markers of multidrug-resistant TB (MDR). We assessed the performances of the test on a collection of strains (n = 54) and a set of clinical samples (n = 242) from routine practice, comparatively to TB diagnosis and genotypic drug susceptibility testing (gDST) as references. Regarding the 242 clinical samples, the sensitivity and specificity of MTB detection by ELITe were 90.9% and 97.5%, respectively. For the detection of resistance-conferring mutations on positive clinical samples, we observed perfect agreement with gDST for katG and pro-inhA (κ = 1.0) and two discordant results for rpoB (κ = 0.82). Considering the 54 cultured strains, very good agreement with gDST was observed for the detection of the 25 distinct mutations in rpoB, katG, and pro-inhA, (κ = 0.95, 0.88, and 0.95, respectively). In conclusion, the automated MDR/MTB ELITe MGB® assay shows great promise and appears to be a valuable tool for rapid detection of pre-MDR- and MDR-TB directly from clinical specimens.
Highlights
Antibiotic resistance is a major threat to tuberculosis (TB) control
The World Health Organization (WHO)-endorsed Xpert® Mycobacterium tuberculosis complex (MTB)/RIF assay (Cepheid, Sunnyvale, CA, USA) has the advantage of being fully automated but provides limited information as it can only detect rpoB mutations involved in RIF-R but not INH-R, which can significantly impact first-line regimen success
Performances of multidrug-resistant TB (MDR)/MTB ELITe MGB® Assay on Routine Clinical Specimens
Summary
Antibiotic resistance is a major threat to tuberculosis (TB) control. Efficient patient care needs early and accurate detection of Mycobacterium tuberculosis complex (MTB) and identification of resistance to rifampicin (RIF-R) and isoniazid (INH-R) [1]. GenoType MTBDRplus (Hain Lifescience, Nehren, Germany) assay is recommended by the WHO for direct testing of smear-positive specimens and MTB isolates. It permits the detection within 48 h of the most frequent mutations in rpoB and in katG genes, and inhA promoter (pro-inhA), which cause RIF-R and INH-R, respectively [5,6,7]. This line-probe assay is not automated and is time-consuming. Automation does not comprise DNA extraction [8]
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