Simultaneous detection of Mycobacterium tuberculosis complex and resistance to Rifampicin and Isoniazid by MDR/MTB ELITe MGB® Kit for the diagnosis of tuberculosis

Abstract

The MDR/MTB ELITe MGB ® Kit on the ELITe InGenius ® platform (ELITechGroup SpA, Italy) is the first system for simultaneous detection of the Mycobacterium tuberculosis complex (MTBc) genome and the main mutations responsible for resistance to Isoniazid (inhA, katG) and Rifampicin (rpoB), from decontaminated and heat inactivated samples. In this study we compared the performance of the MDR/MTB ELITe MGB ® Kit (ELITe) with culture in 100 pulmonary and 160 extra-pulmonary samples. The sensitivity and specificity of ELITe compared to culture for pulmonary samples were 98.0% and 98.0% respectively; for extrapulmonary samples the overall sensitivity was 86.3% (80% for urine, 85% for biopsy and gastric aspirate and 95% for cavitary fluid) and specificity was 100%. Genotypic Isoniazid and Rifampicin susceptibility typing was feasible in 96% of sputum MTBc-positive samples and 43% of extra-pulmonary samples; all samples were found to be drug susceptible by phenotypic and ELITe (100% agreement). Detection of mutations in the rpoB, kat G or inhA genes was evaluated on 300 spiked samples (60 per biological matrix) and all resistance profiles were correctly identified by ELITe. Molecular agreement between ELITe and Xpert was 98.0% and 93.3% for pulmonary and extra-pulmonary samples, respectively. In conclusion, our results provide evidence to support the use of MDR/MTB ELITe MGB ® Kit in combination with ELITe InGenius ® for the diagnosis of MTBc and the detection of Rifampicin and Isoniazid resistance-related mutations in both pulmonary and extra-pulmonary samples. This system simplifies the laboratory workflow, shortens report time and is an aid in choosing appropriate therapeutic treatment and patient management.

The MTB/MDR ELITe MGB® Kit: Performance Assessment for Pulmonary, Extra-Pulmonary, and Resistant Tuberculosis Diagnosis, and Integration in the Laboratory Workflow of a French Center

“…The sensitivity of the MTB/MDR ELITe MGB ® Kit on the extra-pulmonary samples observed in this study was moderate, and lower than the sensitivity reported by Bisognin et al (86.3%; CI95 (76.7; 92.9)) [10]. Using the Xpert MTB/RIF Ultra, a recent meta-analysis found a much higher sensitivity (85.6%; CI95 (76.7; 91.5)) on extra-pulmonary samples [12], suggesting that the latter test could be more sensitive on this type of sample than the MTB/MDR ELITe MGB ® Kit.…”

“…The overall sensitivity and specificity of the MTB/MDR ELITe MGB ® Kit reported in this study were very good, and the ROC curve analysis indicated a high accuracy of the test for TB diagnosis. Nevertheless, the overall sensitivity and the sensitivity on pulmonary samples were slightly inferior compared to these reported by Bisognin et al (90.8%; CI95 (84.6; 94.6) and 98.0%; CI95 (89.3; 99.9), respectively) [10]. This discrepancy is probably due to the way the samples were selected, as the MTB inoculum was higher in the latter study: a majority of the pulmonary samples were smear-positive (44/50), and when MTB was detected, the Ct of IS6110 was ≤31 (molecular typing feasible) for 95.5% of the pulmonary samples and 46.2% of the extra-pulmonary samples.…”

Rapid Molecular Diagnosis of Tuberculosis and Its Resistance to Rifampicin and Isoniazid with Automated MDR/MTB ELITe MGB® Assay

“…Interestingly, the ELITe assay seems sensitive enough to detect pauci-bacillary TB. Sensitivity was comparable to that published by Bisognin et al [9], and higher than that observed by Hodille et al, in routine clinical context in our study. Considering the ELITe negatives, 15 were smear-positive, among which 13 were due to the non-tuberculosis mycobacteria M. intracellulare (n = 3), M. avium (n = 5), M. fortuitum (n = 1), M. chimaera (n = 2), M. abscessus susp.…”

“…Considering the ELITe negatives, 15 were smear-positive, among which 13 were due to the non-tuberculosis mycobacteria M. intracellulare (n = 3), M. avium (n = 5), M. fortuitum (n = 1), M. chimaera (n = 2), M. abscessus susp. bolletii (n = 1), and M. genavense (n = 1), and 2 were false-positive microscopic examinations likely due to Corynebacterium spp., indicating very high specificity of ELITe assay, which was also observed by Bisognin et al (99.23%) and Hodille et al (100%) [9,10]. Among the nine discordant results, four were false-negative ELITe results obtained from four culturediagnosed TB with negative microscopic examinations owing to their low bacillary load in the specimens.…”

“…Automation has the advantage of obtaining results in 3 h, with all steps included from sample to results, thus reducing time-to-result and making it possible to initiate early adapted treatment, especially in case of MDR-TB. The assay was first evaluated by Bisognin et al but on frozen samples spiked with mutated strains [9]. Recently, a second study by Hodille et al was performed retrospectively on clinical samples (n = 54) and strains (n = 25) [10].…”