Using Xpert MTB/RIF

Nicol, Mark P.; Whitelaw, Andrew; Stevens, Wendy

doi:10.2174/1573398x113099990015

Cited by 17 publications

(16 citation statements)

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“…Considering also that the GeneXpert MTB/RIF performs well as a rapid diagnostic for M. tuberculosis [20][21][22], observations described in rpoB gene at level of wildtype probe 8 could be due to mutation at the codon 533. Although DNA sequencing of rpoB gene is required for confi rmation, the combination of results of MGIT-DST and GeneXpert (two methods with good performances for detection of RMP resistance) and hypothesis of mutation at codon 533 should be sustained.…”

Section: Discussionmentioning

confidence: 99%

Assessment of the GenoType MTBDRplus assay for rifampin and isoniazid resistance detection on sputum samples in Cote d'Ivoire

N’guessan¹,

Assi²,

Ouassa³

et al. 2014

European Journal of Microbiology and Immunology

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We conducted an evaluation study on the GenoType MTBDRplus assay's ability to detect mutations conferring resistance to rifampin and isoniazid directly from sputum taken from 120 smear positive pulmonary patients from tuberculosis (TB) centers in Cote d'Ivoire.The sputum was decontaminated by N-acetyl-l-cysteine (NALC) and comparatively analyzed with the MTBDRplus assay version 2.0 and the mycobacterial growth indicator tube (MGIT) 960 automated drug susceptibility testing (MGIT-DST). The GeneXpert Mycobacterium tuberculosis (MTB)/rifampicin (RIF) assay was performed for 21 sputa with absence of hybridization for at least one rpoB wild-type probes. Four and seven, respectively, discordant and concordant results were also analyzed.The mutations in the rpoB gene were 21 (17.5%), 20 (16.7%), 7 (5.8%), and 10 (8.3%), respectively, for D516V, H526Y, H526D, and S531L. S315T mutation in katG gene associated or not with mutation in promoter of inhA was detected in 76 (63.3%) of the sputum. Compared to MGIT-DST, the sensitivity and specificity of the MTBDRplus for rifampin resistance detection were 100% (75-100%) and 73.2% (61.3-84%), respectively. For isoniazid resistance detection, the sensitivity and specificity were, respectively, 95% (90-99) and 95.1% (88.5-100%).Interpretation of 16 sputa without hybridization of rpoB wild-type probe 8 compared to those obtained with MGIT-DST and GeneXpert MTB/RIF was discordant and concordant, respectively, for 11 and 5.

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Section: Discussionmentioning

confidence: 99%

Assessment of the GenoType MTBDRplus assay for rifampin and isoniazid resistance detection on sputum samples in Cote d'Ivoire

N’guessan¹,

Assi²,

Ouassa³

et al. 2014

European Journal of Microbiology and Immunology

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“…The POC must contain a hood for handling class 2 clinical samples, storage at room temperature (controlled at 20°C Ϯ 2°C), a refrigerator for storage at 4°C Ϯ 1°C, a computer connected to the core laboratory, an automatic cell counter for the diagnosis of meningitis, a reader for immunochromatographic tests (optional), a nucleic acid extractor, and a thermocycler, with the latter two instruments optionally being combined into one, such as in the GeneXpert, BioFire, and Cobas Liat system formats (4,5,66). Other advantages of the Xpert system include the ability to use each machine module independently, allowing several samples to be screened simultaneously (74). In addition, the instrument is robust, portable, and easy to use and requires only minimal maintenance (75).…”

Section: Instrumentsmentioning

confidence: 99%

The Point-of-Care Laboratory in Clinical Microbiology

et al. 2016

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International audiencePoint-of-care (POC) laboratories that deliver rapid diagnoses of ă infectious diseases were invented to balance the centralization of core ă laboratories. POC laboratories operate 24 h a day and 7 days a week to ă provide diagnoses within 2 h, largely based on immunochromatography and ă real-time PCR tests. In our experience, these tests are conveniently ă combined into syndrome-based kits that facilitate sampling, including ă self-sampling and test operations, as POC laboratories can be operated ă by trained operators who are not necessarily biologists. POC ă laboratories are a way of easily providing clinical microbiology testing ă for populations distant from laboratories in developing and developed ă countries and on ships. Modern Internet connections enable support from ă core laboratories. The cost-effectiveness of POC laboratories has been ă established for the rapid diagnosis of tuberculosis and sexually ă transmitted infections in both developed and developing countries

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“…In children, the sensitivity of culture varies (range 1.5%–65%) depending on age, disease severity, number of specimens collected and disease prevalence of the setting [ 5 – 8 ]. The introduction of the Xpert MTB/RIF assay (Xpert; Cepheid, Sunnyvale, CA, USA) brought promise as it showed improved sensitivity, specificity and accuracy compared to smear microscopy in culture-positive pediatric cases [ 5 , 9 , 10 ]. Xpert was endorsed by World Health Organization (WHO) as an initial diagnostic test in children, though as a conditional recommendation with very low quality of evidence [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Why being an expert – despite xpert –remains crucial for children in high TB burden settings

et al. 2017

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BackgroundAs access to Xpert expands in high TB-burden settings, its performance against clinically diagnosed TB as a reference standard provides important insight as the majority of childhood TB is bacteriologically unconfirmed. We aim to describe the characteristics and outcomes of children with presumptive TB and TB disease, and assess performance of Xpert under programmatic conditions against a clinical diagnosis of TB as a reference standard.MethodsRetrospective review of children evaluated for presumptive TB in Mbeya, Tanzania. Baseline characteristics were compared by TB disease status and, for patients diagnosed with TB, by TB confirmation status using Wilcoxon rank sum test for continuous variables and the Chi-square test for categorical variables. Sensitivity and specificity were calculated to assess the performance of Xpert, smear, and culture against clinical TB. Kappa statistics were calculated to assess agreement between Xpert and smear to culture.ResultsAmong children (N = 455) evaluated for presumptive TB, 70.3% (320/455) had Xpert and 62.8% (286/455) had culture performed on sputa. 34.5% (157/455) were diagnosed with TB: 80.3% (126/157) pulmonary TB, 13.4% (21/157) bacteriologically confirmed, 53.5% (84/157) HIV positive, and 48.4% (76/157) inpatients. Compared to the reference standard of clinical diagnosis, sensitivity of Xpert was 8% (95% CI 4–15), smear 6% (95% CI 3–12) and culture 16% (95% CI 9–24), and did not differ based on patient disposition, nutrition or HIV status.ConclusionDespite access to Xpert, the majority of children with presumptive TB were treated based on clinical diagnosis. Reflecting the reality of clinical practice in resource limited settings, new diagnostics such as Xpert serve as important adjunctive tests but will not obviate the need for astute clinicians and comprehensive diagnostic algorithms.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-017-2236-9) contains supplementary material, which is available to authorized users.

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Using Xpert MTB/RIF

Cited by 17 publications

References 44 publications

Assessment of the GenoType MTBDRplus assay for rifampin and isoniazid resistance detection on sputum samples in Cote d'Ivoire

Assessment of the GenoType MTBDRplus assay for rifampin and isoniazid resistance detection on sputum samples in Cote d'Ivoire

The Point-of-Care Laboratory in Clinical Microbiology

Why being an expert – despite xpert –remains crucial for children in high TB burden settings

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