Potential of two nucleic acid amplification assays for quantifying mycobacterial load in respiratory and non-respiratory specimens: a prospective study

Alnimr, Amani; Hassan, Manal

doi:10.1016/j.diagmicrobio.2013.11.020

Cited by 11 publications

(14 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…ROC analysis revealed an area under the curve (AUC) of 0.85 (95%CI 0.82-0.87). Cut-off C T values of 27.7 and 31.8 yielded sensitivities of 85% (95%CI [83][84][85][86][87] and 95% (95%CI 94-96) and specificities of 67% (95%CI [66][67][68][69][70][71][72][73][74][75][76][77] and 35% (95%CI [30][31][32][33][34][35][36][37][38][39][40][41] for smear-positive samples. C O N C L U S I O N : Xpert C T values and smear status were strongly associated.…”

Section: S U M M a R Y S E T T I N Gmentioning

confidence: 99%

See 1 more Smart Citation

Diagnostic accuracy of the Xpert^® MTB/RIF cycle threshold level to predict smear positivity: a meta-analysis

Lange

Khan

Kalmambetova

et al. 2017

int j tuberc lung dis

View full text Add to dashboard Cite

show abstract

Section: S U M M a R Y S E T T I N Gmentioning

confidence: 99%

“…Search strategy for systematic reviewTable A.2 All studies potentially able to provide individual level patient data:[83][84][85][86][87][88][89][90][91][92] studies included in the descriptive systematic review on C T values, in grey studies contributing individual-level data to the meta-analysis…”

mentioning

confidence: 99%

Diagnostic accuracy of the Xpert^® MTB/RIF cycle threshold level to predict smear positivity: a meta-analysis

Lange

Khan

Kalmambetova

et al. 2017

int j tuberc lung dis

View full text Add to dashboard Cite

show abstract

“…While TB is diagnosed using a qualitative approach, with clinical decisions made on presence or absence of the pathogen, it also represents an example where pathogen quantification is desirable as a potential indicator to determine treatment efficacy and predict relapse. Quantification is currently applied in patient management by grading of smear positivity and there are a number of studies that have used more sophisticated culture based quantitative metrics such as CFU counting and time to positivity [ 9 , 10 ] as well a molecular based methods targeting RNA [ 11 , 12 ] and DNA using PCR [ 13 , 14 ] and, increasingly, qPCR using the Xpert MTB/RIF [ 15 – 18 ]. Where the quantitative capabilities of the Xpert MTB/RIF have been evaluated its value as a quantitative method is equivocal.…”

Section: Introductionmentioning

confidence: 99%

The use of digital PCR to improve the application of quantitative molecular diagnostic methods for tuberculosis

Devonshire¹,

O’Sullivan²,

Honeyborne

et al. 2016

BMC Infect Dis

View full text Add to dashboard Cite

BackgroundReal-time PCR (qPCR) based methods, such as the Xpert MTB/RIF, are increasingly being used to diagnose tuberculosis (TB). While qualitative methods are adequate for diagnosis, the therapeutic monitoring of TB patients requires quantitative methods currently performed using smear microscopy. The potential use of quantitative molecular measurements for therapeutic monitoring has been investigated but findings have been variable and inconclusive. The lack of an adequate reference method and reference materials is a barrier to understanding the source of such disagreement. Digital PCR (dPCR) offers the potential for an accurate method for quantification of specific DNA sequences in reference materials which can be used to evaluate quantitative molecular methods for TB treatment monitoring.MethodsTo assess a novel approach for the development of quality assurance materials we used dPCR to quantify specific DNA sequences in a range of prototype reference materials and evaluated accuracy between different laboratories and instruments. The materials were then also used to evaluate the quantitative performance of qPCR and Xpert MTB/RIF in eight clinical testing laboratories.ResultsdPCR was found to provide results in good agreement with the other methods tested and to be highly reproducible between laboratories without calibration even when using different instruments. When the reference materials were analysed with qPCR and Xpert MTB/RIF by clinical laboratories, all laboratories were able to correctly rank the reference materials according to concentration, however there was a marked difference in the measured magnitude.ConclusionsTB is a disease where the quantification of the pathogen could lead to better patient management and qPCR methods offer the potential to rapidly perform such analysis. However, our findings suggest that when precisely characterised materials are used to evaluate qPCR methods, the measurement result variation is too high to determine whether molecular quantification of Mycobacterium tuberculosis would provide a clinically useful readout. The methods described in this study provide a means by which the technical performance of quantitative molecular methods can be evaluated independently of clinical variability to improve accuracy of measurement results. These will assist in ultimately increasing the likelihood that such approaches could be used to improve patient management of TB.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-016-1696-7) contains supplementary material, which is available to authorized users.

show abstract

“…In the past decades, several methods have been developed for TB diagnosis, including tuberculin skin test (TST), sputum smear and culture test, and nucleic acid amplification test [ 3 – 6 ]. Despite the use of these tests, it is still difficult to diagnose TB quickly and accurately in clinical practice [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

Identification of Novel RD1 Antigens and Their Combinations for Diagnosis of Sputum Smear−/Culture+ TB Patients

Liu¹,

Qie²,

et al. 2016

BioMed Research International

View full text Add to dashboard Cite

Rapid and accurate diagnosis of pulmonary tuberculosis (PTB) is an unresolved problem worldwide, especially for sputum smear− (S−) cases. In this study, five antigen genes including Rv3871, Rv3874, Rv3875, Rv3876, and Rv3879 were cloned from Mycobacterium tuberculosis (Mtb) RD1 and overexpressed to generate antigen fragments. These antigens and their combinations were investigated for PTB serodiagnosis. 298 serum samples were collected from active PTB patients, including 117 sputum smear+ (S+) and sputum culture+ (C+) cases, 101 S−/C+ cases, and 80 S−/C− cases. The serum IgG levels of the five antigens were measured by ELISA. Based on IgG levels, the sensitivity/specificity of Rv3871, Rv3874, Rv3875, Rv3876, and Rv3879 for PTB detection was 81.21%/74.74%, 63.09%/94.78%, 32.21%/87.37%, 62.42%/85.26%, and 83.56%/83.16%, respectively. Furthermore, the optimal result for PTB diagnosis was achieved by combining antigens Rv3871, Rv3876, and Rv3879. In addition, the IgG levels of Rv3871, Rv3876, and Rv3879 were found to be higher in S−/C+ PTB patients than in other PTB populations. More importantly, combination of the three antigens demonstrated superior diagnostic performance for both S−/C+ and S−/C− PTB. In conclusion, the combination of Rv3871, Rv3876, and Rv3879 induced higher IgG response in sputum S−/C+ PTB patients and represents a promising biomarker combination for diagnosing of PTB.

show abstract

Potential of two nucleic acid amplification assays for quantifying mycobacterial load in respiratory and non-respiratory specimens: a prospective study

Cited by 11 publications

References 17 publications

Diagnostic accuracy of the Xpert^® MTB/RIF cycle threshold level to predict smear positivity: a meta-analysis

Diagnostic accuracy of the Xpert^® MTB/RIF cycle threshold level to predict smear positivity: a meta-analysis

The use of digital PCR to improve the application of quantitative molecular diagnostic methods for tuberculosis

Identification of Novel RD1 Antigens and Their Combinations for Diagnosis of Sputum Smear−/Culture+ TB Patients

Contact Info

Product

Resources

About

Potential of two nucleic acid amplification assays for quantifying mycobacterial load in respiratory and non-respiratory specimens: a prospective study

Cited by 11 publications

References 17 publications

Diagnostic accuracy of the Xpert® MTB/RIF cycle threshold level to predict smear positivity: a meta-analysis

Diagnostic accuracy of the Xpert® MTB/RIF cycle threshold level to predict smear positivity: a meta-analysis

The use of digital PCR to improve the application of quantitative molecular diagnostic methods for tuberculosis

Identification of Novel RD1 Antigens and Their Combinations for Diagnosis of Sputum Smear−/Culture+ TB Patients

Contact Info

Product

Resources

About

Diagnostic accuracy of the Xpert^® MTB/RIF cycle threshold level to predict smear positivity: a meta-analysis

Diagnostic accuracy of the Xpert^® MTB/RIF cycle threshold level to predict smear positivity: a meta-analysis