van Zyl-Smit, RN;
Binder, A;
Meldau, R;
Mishra, H;
Semple, PL;
Theron, G;
Peter, J;
... Dheda, K; + view all
(2011)
Comparison of Quantitative Techniques including Xpert MTB/RIF to Evaluate Mycobacterial Burden.
PLOS ONE
, 6
(12)
, Article e28815. 10.1371/journal.pone.0028815.
![[thumbnail of 1369881.pdf]](https://discovery.ucl.ac.uk/style/images/fileicons/application_pdf.png) Preview |
PDF
1369881.pdf Download (563kB) |
Abstract
Introduction: Accurate quantification of mycobacterial load is important for the evaluation of patient infectiousness, disease severity and monitoring treatment response in human and in-vitro laboratory models of disease. We hypothesized that newer techniques would perform as well as solid media culture to quantify mycobacterial burden in laboratory specimens. Methods: We compared the turn-around-time, detection-threshold, dynamic range, reproducibility, relative discriminative ability, of 4 mycobacterial load determination techniques: automated liquid culture (BACTEC-MGIT-960), [3H]-uracil incorporation assays, luciferase-reporter construct bioluminescence, and quantitative PCR(Xpert -MTB/RIF) using serial dilutions of Mycobacterium bovis and Mycobacterium tuberculosis H37RV. Mycobacterial colony-forming-units(CFU) using 7H10-Middlebrook solid media served as the reference standard. Results: All 4 assays correlated well with the reference standard, however, bioluminescence and uracil assays had a detection threshold ≥1×103 organisms. By contrast, BACTEC-MGIT-960 liquid culture, although only providing results in days, was user-friendly, had the lowest detection threshold (<10 organisms), the greatest discriminative ability (1 vs. 10 organisms; p = 0.02), and the best reproducibility (coefficient of variance of 2% vs. 38% compared to uracil incorporation; p = 0.02). Xpert-MTB/RIF correlated well with mycobacterial load, had a rapid turn-around-time (<2 hours), was user friendly, but had a detection limit of ~100 organisms. Conclusions: Choosing a technique to quantify mycobacterial burden for laboratory or clinical research depends on availability of resources and the question being addressed. Automated liquid culture has good discriminative ability and low detection threshold but results are only obtained in days. Xpert MTB/RIF provides rapid quantification of mycobacterial burden, but has a poorer discrimination and detection threshold.
| Type: | Article |
|---|---|
| Title: | Comparison of Quantitative Techniques including Xpert MTB/RIF to Evaluate Mycobacterial Burden |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1371/journal.pone.0028815 |
| Publisher version: | http://dx.doi.org/10.1371/journal.pone.0028815 |
| Language: | English |
| Additional information: | © 2011 van Zyl-Smit et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. RVZS is supported in part by a Fogarty International Clinical Research Scholars/Fellows Support Centre National Institutes of Health grant R24TW007988. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. No additional external funding was received for this study. |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1369881 |
Archive Staff Only
 |
View Item |
