Dataset Information

Evaluation of the Roche cobas MTB and MTB-RIF/INH Assays in Samples from Germany and Sierra Leone.

ABSTRACT: The Roche cobas MTB and MTB-RIF/INH assays allow for detection of Mycobacterium tuberculosis complex (MTBC) nucleic acid and rifampicin (RIF) and isoniazid (INH) resistance-associated mutations in an automated, high-throughput workflow. In this study, we evaluated the performance of these assays, employing samples from settings of low and high tuberculosis (TB) burdens. A total of 325 frozen, leftover respiratory samples collected from treatment-naive patients with presumptive TB in Germany (n = 280) and presumptive RIF-resistant TB in Sierra Leone (n = 45) were used in this study. cobas MTB results for detection of MTBC DNA from N-acetyl-l-cysteine-sodium hydroxide (NALC-NaOH)-treated samples were compared to culture results. Predictions of RIF and INH resistance by the cobas MTB-RIF/INH assay were compared to a composite reference standard (phenotypic drug susceptibility testing and line probe assay). Whole-genome sequencing was used to resolve discordances. The overall sensitivity of cobas MTB for detection of MTBC DNA in culture-positive samples (n = 102) was 89.2% (95% confidence interval [CI], 81.7 to 93.9%). The specificity of cobas MTB was 98.6% (95% CI, 96.1 to 99.5%). Sensitivity and specificity for detection of RIF and INH resistance were 88.4% (95% CI, 75.5 to 94.9%) and 97.6% (95% CI, 87.4 to 99.6%) and 76.6% (95% CI, 62.8 to 86.4%) and 100.0% (95% CI, 90.8 to 100.0%), respectively. Discordant results for RIF and INH resistance were mainly due to uncommon mutations in samples from Sierra Leone that were not covered by the cobas MTB-RIF/INH assay. In conclusion, cobas MTB and MTB-RIF/INH assays provide accurate detection of MTBC DNA and resistance-associated mutations in respiratory samples. The influence of regional variations in the prevalence of resistance-conferring mutations requires further investigation.

SUBMITTER: Nadarajan D

PROVIDER: S-EPMC8091830 | biostudies-literature | 2021 Apr

REPOSITORIES: biostudies-literature

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Evaluation of the Roche cobas MTB and MTB-RIF/INH Assays in Samples from Germany and Sierra Leone.

Nadarajan Darshaalini D Hillemann Doris D Kamara Rashidatu R Foray Lynda L Conteh Ousman S OS Merker Matthias M Niemann Stefan S Lau Jasmine J Njoya Merlin M Kranzer Katharina K Somoskovi Akos A Maurer Florian P FP

Journal of clinical microbiology 20210420 5

The Roche cobas MTB and MTB-RIF/INH assays allow for detection of <i>Mycobacterium tuberculosis</i> complex (MTBC) nucleic acid and rifampicin (RIF) and isoniazid (INH) resistance-associated mutations in an automated, high-throughput workflow. In this study, we evaluated the performance of these assays, employing samples from settings of low and high tuberculosis (TB) burdens. A total of 325 frozen, leftover respiratory samples collected from treatment-naive patients with presumptive TB in Germa ...[more]

PMID: 33658264

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Project description:South Africa is a country with a high incidence of tuberculosis (TB), complicated by coinfection with human immunodeficiency virus (HIV). The Xpert MTB/RIF (Cepheid, Sunnyvale, CA, USA) is used in South Africa as the test for the initial diagnosis of TB, and other molecular platforms such as the m2000 (Abbott Molecular, Des Plaines, IL, USA) are widely used for molecular monitoring of HIV load. The latter platform is now also equipped with the RealTime (RT) MTB and RealTime MTB RIF/INH assays for TB and first-line drug resistance screening but has not been evaluated in settings of HIV and TB coinfection. A prospective clinical validation study was conducted at a community health center in Johannesburg, South Africa, and consenting individuals with presumptive pulmonary TB were enrolled. The performance of the Abbott assays was compared with those of the Xpert MTB/RIF, liquid culture, drug susceptibility testing, and clinical case definitions. A statistical analysis was performed on 206 individuals (73% were HIV positive). The sensitivity and specificity of the RT MTB were 82.5% (confidence interval [CI], 67.2 to 92.7) and 93.1% (CI, 86.2 to 97.2) on raw sputum and 77.5% (CI, 61.5 to 89.2) and 95.1% (CI, 88.9 to 98.4) on concentrated sputum, respectively, compared with those from liquid culture. The RT MTB correctly identified 17/35 more smear-negative culture-positive specimens than the Xpert MTB/RIF. Both the RT MTB and the Xpert MTB/RIF displayed sensitivities >70% and specificities >90% in HIV-positive individuals. The available drug resistance results concurred with MTBDRplus and drug susceptibility profiles. The RT MTB assay has similar diagnostic performance to the Xpert MTB/RIF and is suited to testing presumptive TB patients coinfected with HIV. The existing laboratory information system connectivity, training, and technical support make this a viable polyvalent option to scale up TB alongside HIV laboratory testing services in South Africa.

Project description:BackgroundThe Abbott RealTime MTB is an assay for the detection of Mycobacterium tuberculosis (MTB) complex DNA from respiratory specimens in combination with the Abbott RealTime RIF/INH assay for the detection of genetic resistance markers for isoniazid (INH) and rifampicin (RIF) from MTB positive isolates. Hence, this study aimed to evaluate the performance of the Abbott RealTime MTB and RIF/INH assays.MethodsA cross-sectional study was conducted on 289 study subjects presumptive to have pulmonary tuberculosis at Nigist Eleni Mohammed Memorial Hospital, South Ethiopia from April 2017 to June 2018. Two morning expectorated sputum specimens were collected from each study participant. One sample was tested directly by Xpert MTB/RIF assay at Nigist Eleni Mohammed Memorial Hospital and the other sample was used for smear microscopy, TB culture, Abbott RealTime MTB, and Abbott RealTime INH/RIF assays at International Clinical Laboratories, Addis Ababa, Ethiopia. The diagnostic performance of the Abbott RealTime MTB and INH/RIF assays were calculated against MGIT liquid culture and phenotypic drug susceptibility testing (DST) as the gold standard.ResultsFor the detection of MTB the Abbott RealTime MTB assay exhibited sensitivity 92.4% (95% CI 83.6-96.9), specificity 95.4% (95% CI 91.1-97.7), PPV 89.0% (95% CI 79.7-94.5) and NPV 96.9% (95% CI 93.0-98.7). For the detection of RIF resistance MTB, Abbott RealTime MTB RIF/INH concurred with phenotypic DST and Xpert MTB/RIF, while for the detection of INH resistance MTB, the sensitivity, specificity, PPV and NPV of the Abbott MTB RIF/INH assay was 84.2% (95% CI 60.4-96.6), 100% (95% CI 89.7-100), 100% and 91.9% (95% CI 80.0-96.9), respectively.ConclusionsThe Abbott RTMTB and RIF/INH assays revealed high sensitivity and specificity in MTB diagnosis and provided reliable INH and RIF resistance profiles. This assay has a similar diagnostic performance to the Xpert MTB/RIF assay with the advantages of high-throughput.

Project description:BackgroundThe World Health Organization endorsed Truenat MTB rapid molecular assay in 2020 and recommended additional in-country evaluation studies before uptake. We evaluated the accuracy and operational feasibility of Truenat MTB assay (Truenat) in comparison with GeneXpert Ultra and culture.MethodsIn a cross-sectional study of 250 presumptive TB patients, participants were requested to provide a sputum sample on the day of their visit to the clinic. The sputum sample was homogenized and a portion was tested using GeneXpert Ultra as per the routine standard procedure and the other portion was tested using Truenat assay at the clinic laboratory. The second sample portion was processed for Concentrated Fluorescent smear Microscopy (CFM), LJ, and MGIT cultures. Truenat sensitivity and specificity were compared to GeneXpert Ultra and culture. Test performance characteristics and operational feasibility assessment data through interview of the study laboratory staff were also collected and summarized as proportions and percentages.ResultsOf the 250 participants recruited in the study, the sensitivity and specificity of Truenat was n/N (%, 95%CI); 66/82 (80.5, 70.2-88.4) and 156/159 (98.1, 94.5-99.6) when compared with Ultra, 50/64 (89.3, 66.0-87.4) and 166/180 (92.2, 87.2-95.6) when compared with LJ, 58/71 (81.7,70.7-89.8) and 131/138 (94.9, 89.8-97.9) when compared to MGIT culture and 59/73 (80.8, 69.9-89.1) and 159/169 (94.1,89.3-97.1) when compared to LJ and/or MGIT culture. The sensitivity of Truenat was lower, 14/23 (60.9, 40.6-82.8) among smear-negative compared to 45/50 (90.0, 78.1-96.6) among smear-positive participants but not different by HIV status. There were no special training needs especially among laboratory personnel with previous GeneXpert /molecular test experience, 19/242 (7.8%) error/invalid, and 12 (17,4%) uninterpretable/indeterminate results mainly for rifampicin resistance determination. However, there were 3 (3.5%) of GeneXpert Ultra indeterminate results.ConclusionAmong presumptive TB patients in Uganda, the Truenat assay has high sensitivity and specificity. The Truenat assay has acceptable operational feasibility attributes when compared with the GeneXpert Assay.

Dataset Information

Evaluation of the Roche cobas MTB and MTB-RIF/INH Assays in Samples from Germany and Sierra Leone.

Publications

Evaluation of the Roche cobas MTB and MTB-RIF/INH Assays in Samples from Germany and Sierra Leone.

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