Predictive value of PCR applied to clinical samples for Mycobacterium tuberculosis detection.

1994 ◽  
Vol 32 (1) ◽  
pp. 273
Author(s):  
D Raoult
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Predictive Value ◽  
Clinical Samples

scholarly journals High-resolution melt curve analysis for rapid detection of rifampicin resistance in mycobacterium tuberculosis: A single-center study in Iran

2019 ◽  
Author(s):  
Samaneh Arefzadeh ◽  
Mohammad Javad Nasiri ◽  
Taher Azimi ◽  
Zahra Nikpor ◽  
Hossein Dabiri ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
High Resolution ◽  
Diagnostic Accuracy ◽  
Predictive Value ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Clinical Samples ◽  
High Resolution Melt ◽  
Cross Sectional ◽  
Risk Of Death

AbstractIntroductionTuberculosis (TB) remains a leading cause of death worldwide, especially in developing countries. Early detection of resistance is extremely important to reduce the risk of death. This study was aimed to compare the diagnostic accuracy of high resolution melting (HRM) analysis in comparison with Xpert MTB/RIF as well as conventional drug susceptibility testing (DST) for the detection of rifampicin (RIF) resistance in Mycobacterium tuberculosis in Iran.Materials and methodsA comparative cross-sectional study was carried out from April 2017 to September 2018. A total of 80 culture-positive clinical samples selected during the study period were analyzed for detection of RIF-resistant TB by conventional DST, Xpert MTB/RIF, and sequencing. Sensitivity and specificity of the HRM calculated according to DST as our gold standard test in this study.ResultsThe overall sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of HRM assay were found to be 100%, 89.33%, 38.46%, and 100% respectively.ConclusionsThe analysis has demonstrated that the diagnostic accuracy of HRM tests is insufficient to replace Xpert MTB/RIF and conventional DST. HRM test may be used in combination with culture due to the advantage of the time to result. Further work to improve molecular tests would benefit from standardized reference standards and the methodology.

DETECTING MYCOBACTERIUM TUBERCULOSIS RAPIDLY AND MYCOBACTERIUM TUBERCULOSIS STRAINS WITHOUT IS6110 SEQUENCE BY PCR ASSAY

2012 ◽  
pp. 15-19
Author(s):  
Thi Chau Anh Nguyen ◽  
Hoang Bach Nguyen ◽  
Hai Duong Huynh ◽  
Nu Xuan Thanh Le ◽  
Xuan Cuong Le ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
16S Rdna ◽  
False Negative ◽  
Clinical Samples ◽  
Tuberculosis Complex ◽  
Pcr Assay ◽  
Complex Objects ◽  
Method Performance ◽  
Gene Coding ◽  
16S Rdna Pcr

Background: The Nested IS6110 PCR is used for detecting tuberculosis, however IS6110 sequence is not present in the genome of all strains of M.tuberculosis, the result may be false negative. The gene coding 16S ribosome always contains a short sequence specific to M. tuberculosis complex. Objects: Performance of the 16S Real-time PCR to detect M. tuberculosis and combining to the nested IS6110 PCR to determine the rate of Mtb strains without IS6110 from clinical samples. Materials and method: Performance of 16S rDNA PCR by commercial kit of Viet A Inc. for all 480 samples, the samples which were positive with the 16S rDNA PCR were retested in IS6110 PCR assay by in-house kit. Results: The Realtime 16S rDNA PCR detected 258 cases (53.8%) of tuberculosis. There were 3 (1.2 %) M. tuberculosis strains which do not harbor IS6110 sequence in genome. Conclusion: The IS6110 nested PCR can be applied more widely than the 16S rDNA realtime PCR. In case of using IS6110 PCR assay, results may show a low proportion of false negative. Combining 16S rDNA PCR with the IS6110 based PCR allowed detection of deletion of IS6110 sequence in M. tuberculosis isolates.

scholarly journals Mutations in fbiD (Rv2983) as a Novel Determinant of Resistance to Pretomanid and Delamanid in Mycobacterium tuberculosis

2020 ◽  
Vol 65 (1) ◽  
pp. e01948-20
Author(s):  
Dalin Rifat ◽  
Si-Yang Li ◽  
Thomas Ioerger ◽  
Keshav Shah ◽  
Jean-Philippe Lanoix ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Clinical Evidence ◽  
Clinical Samples ◽  
Loss Of Function ◽  
Wild Type ◽  
Content Type ◽  
Solid Media ◽  
High Level ◽  
Level Resistance

ABSTRACTThe nitroimidazole prodrugs delamanid and pretomanid comprise one of only two new antimicrobial classes approved to treat tuberculosis (TB) in 50 years. Prior in vitro studies suggest a relatively low barrier to nitroimidazole resistance in Mycobacterium tuberculosis, but clinical evidence is limited to date. We selected pretomanid-resistant M. tuberculosis mutants in two mouse models of TB using a range of pretomanid doses. The frequency of spontaneous resistance was approximately 10−5 CFU. Whole-genome sequencing of 161 resistant isolates from 47 mice revealed 99 unique mutations, of which 91% occurred in 1 of 5 genes previously associated with nitroimidazole activation and resistance, namely, fbiC (56%), fbiA (15%), ddn (12%), fgd (4%), and fbiB (4%). Nearly all mutations were unique to a single mouse and not previously identified. The remaining 9% of resistant mutants harbored mutations in Rv2983 (fbiD), a gene not previously associated with nitroimidazole resistance but recently shown to be a guanylyltransferase necessary for cofactor F420 synthesis. Most mutants exhibited high-level resistance to pretomanid and delamanid, although Rv2983 and fbiB mutants exhibited high-level pretomanid resistance but relatively small changes in delamanid susceptibility. Complementing an Rv2983 mutant with wild-type Rv2983 restored susceptibility to pretomanid and delamanid. By quantifying intracellular F420 and its precursor Fo in overexpressing and loss-of-function mutants, we provide further evidence that Rv2983 is necessary for F420 biosynthesis. Finally, Rv2983 mutants and other F420H2-deficient mutants displayed hypersusceptibility to some antibiotics and to concentrations of malachite green found in solid media used to isolate and propagate mycobacteria from clinical samples.

scholarly journals Microcolony detection in thin layer culture as an alternative method for rapid detection of Mycobacterium tuberculosis in clinical samples

2007 ◽  
Vol 38 (3) ◽  
pp. 421-423 ◽  
Author(s):  
Pedro Eduardo Almeida da Silva ◽  
Fernanda Wiesel ◽  
Maria Marta Santos Boffo ◽  
Andréa von Groll ◽  
Ivo Gomes de Mattos ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Thin Layer ◽  
Rapid Detection ◽  
Clinical Samples ◽  
Alternative Method

scholarly journals Evaluation of the efficacy of two methods for direct extraction of DNA from Mycobacterium tuberculosis sputum

2018 ◽  
Vol 12 (12) ◽  
pp. 1067-1072
Author(s):  
Victor Ndhlovu ◽  
Wilson Mandala ◽  
Derek Sloan ◽  
Mercy Kamdolozi ◽  
Maxine Caws ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Single Molecule ◽  
Disease Transmission ◽  
Extraction Efficiency ◽  
Ease Of Use ◽  
Clinical Samples ◽  
Direct Extraction ◽  
Significant Difference ◽  
Ctab Method ◽  
Dna Purity

Introduction: Whole genome sequencing (WGS) has shown superiority over other bacterial typing methods and can be used to monitor disease transmission. The long culture period hinders use of WGS as a diagnostic tool for TB. The ideal situation would be to efficiently sequence directly from clinical specimens such as sputum. Attempts to sequence directly from Mtb clinical samples have achieved very low coverage (less than 0.7X). We compared DNA extraction methods for direct extraction from Mycobacterium tuberculosis positive sputum and assessed their suitability for Single Molecule Real Time sequencing. Methodology: We evaluated the extraction efficiency of the PrimeXtract kit and an in-house CTAB method by extracting DNA from Mtb sputum. We evaluated the methods on these parameters: ease of use, efficiency (quantity and purity) and the cost per extraction. Results: The PrimeXtract kit was able to isolate 5.93 µg/mL ± 0.94, (Mean ± SEM) concentration of DNA and a yield of 0.2975 µg ± 0.04723, (Mean ± SEM). Comparatively, the CTAB method isolated 1.88 µg/mL ± 0.38 DNA and a yield of 0.09 µg ± 0.02. Both concentration and yield from the kit were significantly (p = 0.0002) higher than those from CTAB. The PrimeXtract kit had a DNA purity ratio of 1.69 ± 0.09 compared to the CTAB’s 1.73 ± 0.14 and this difference was not statistically different. Conclusion: PrimeXtract kit has a superior extraction efficiency than the CTAB method on Mtb sputum in terms of DNA yield although no significant difference by DNA purity was seen.

scholarly journals Development and Performance verification of colloidal gold labeled SARS-CoV-2 antigen detection method for routine popular screening of COVID-19 with clinical samples in Poland and China

2021 ◽  
Author(s):  
Chuanxiang Guo ◽  
Li Yao ◽  
Fengling Chen ◽  
Chao Zhang ◽  
Wei Chen
Keyword(s):  
Predictive Value ◽  
Colloidal Gold ◽  
Detection Method ◽  
Age Distribution ◽  
Antigen Detection ◽  
Lateral Flow ◽  
Rapid Screening ◽  
Clinical Samples ◽  
Lateral Flow Strip ◽  
And Performance

In this research, we have constructed and optimized the colloidal gold labeled lateral flow strip (LFS) for rapid detection of antigen of SARS-CoV-2 and rapid screening of COVID-19. Based on the constructed and optimized colloidal gold lateral flow strip, the parameters of the LFS have been well evaluated with the clinical samples in the professional labs. The screening performance have also been evaluated from the aspects including the CT values, age distribution and onset of symptoms. Finally, based on the detection results of 420 clinical samples, the LFS can achieve the screening of COVID-19 with the positive percentage agreement (PPA, sensitivity), negative percent agreement (NPA, specificity), the positive predictive value (PPV) and the negative predictive value (NPV) of 96.8%, 100%, 100% and 96.6%, respectively, indicating the powerful potential for practical screening applications in pandemic control. Of great significance, this developed SARS-CoV-2 antigen detection method has also been successfully utilized for screening of delta-variant of SARS-CoV-2.

scholarly journals Rapid antibiotic-resistance predictions from genome sequence data for Staphylococcus aureus and Mycobacterium tuberculosis

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Phelim Bradley ◽  
N. Claire Gordon ◽  
Timothy M. Walker ◽  
Laura Dunn ◽  
Simon Heys ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Mycobacterium Tuberculosis ◽  
Sequence Data ◽  
Error Rates ◽  
Graph Representation ◽  
Clinical Samples ◽  
Resistant Bacteria ◽  
Independent Validation ◽  
Validation Set ◽  
Sensitivity Specificity

Abstract The rise of antibiotic-resistant bacteria has led to an urgent need for rapid detection of drug resistance in clinical samples, and improvements in global surveillance. Here we show how de Bruijn graph representation of bacterial diversity can be used to identify species and resistance profiles of clinical isolates. We implement this method for Staphylococcus aureus and Mycobacterium tuberculosis in a software package (‘Mykrobe predictor’) that takes raw sequence data as input, and generates a clinician-friendly report within 3 minutes on a laptop. For S. aureus, the error rates of our method are comparable to gold-standard phenotypic methods, with sensitivity/specificity of 99.1%/99.6% across 12 antibiotics (using an independent validation set, n=470). For M. tuberculosis, our method predicts resistance with sensitivity/specificity of 82.6%/98.5% (independent validation set, n=1,609); sensitivity is lower here, probably because of limited understanding of the underlying genetic mechanisms. We give evidence that minor alleles improve detection of extremely drug-resistant strains, and demonstrate feasibility of the use of emerging single-molecule nanopore sequencing techniques for these purposes.

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