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. 2011 Jul;49(7):2540-5.
doi: 10.1128/JCM.02319-10. Epub 2011 May 18.

Xpert MTB/RIF: a new pillar in diagnosis of extrapulmonary tuberculosis?

Viral Vadwai  1 , Catharina Boehme, Pamela Nabeta, Anjali Shetty, David Alland, Camilla Rodrigues
Affiliations

Xpert MTB/RIF: a new pillar in diagnosis of extrapulmonary tuberculosis?

Viral Vadwai et al. J Clin Microbiol. 2011 Jul.

Abstract

Approximately 10 to 15% of tuberculosis (TB) cases in India are estimated to have extrapulmonary disease, and due to a lack of diagnostic means, they often remain untreated. The early detection of Mycobacterium tuberculosis and multidrug resistance is a priority in TB diagnosis to improve the successful treatment rate of TB and reduce transmission. The Xpert MTB/RIF (Xpert) test, recently endorsed by the World Health Organization for the detection of pulmonary TB, was evaluated to test its utility in 547 patients with suspected extrapulmonary tuberculosis. Five hundred forty-seven extrapulmonary specimens were split and processed simultaneously for both culture (solid and liquid) and Xpert testing. For culture, the sensitivity was low, 53% (150/283 specimens). Xpert sensitivity and specificity results were assessed in comparison to a composite reference standard made up of smear and culture results and clinical, radiological, and histological findings. The sensitivity of the Xpert assay was 81% (228/283 specimens) (64% [89/138] for smear-negative cases and 96% [139/145] for smear-positive cases), with a specificity of 99.6%. The sensitivity was found to be high for the majority of specimen types (63 to 100%) except for cerebrospinal fluid, the sensitivity of which was 29% (2/7 specimens). The Xpert test correctly identified 98% of phenotypic rifampin (RIF)-resistant cases and 94% of phenotypic RIF-susceptible cases. Sequencing of the 6 discrepant samples resolved 3 of them, resulting in an increased specificity of 98%. In conclusion, the results of this study suggest that the Xpert test also shows good potential for the diagnosis of extrapulmonary TB and that its ease of use makes it applicable for countries where TB is endemic.

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Figures

Fig. 1
Fig. 1
Flowchart explaining the patient flow in this study. CT, computed tomography; MRI, magnetic resonance imaging.
Fig. 2
Fig. 2
Forest plot giving details of the sensitivity of the Xpert test against the CRS for each kind of specimen.
See this image and copyright information in PMC

References

    1. Agarwal S. P., Chauhan L. S. 2005. Tuberculosis control in India. Directorate General of Health Services/Ministry of Health and Family Welfare, New Delhi, India
    1. Agresti A., Coull B. 1998. Approximate is better than “exact” for interval estimation of binomial proportions. Am. Stat. 52:119–126
    1. Alonzo T. A., Pepe M. S. 1999. Using a combination of reference tests to assess the accuracy of a new diagnostic test. Stat. Med. 18:2987–3003 - PubMed
    1. Banada P. P., et al. 18 August 2010. Containment of bioaerosol infection risk by the Xpert MTB/RIF assay and its applicability to point-of-care settings. J. Clin. Microbiol. doi:10.1128/JCM.01053-10 - DOI - PMC - PubMed
    1. Barnes P. F. 1997. Rapid diagnostic tests for tuberculosis: progress but no gold standard. Am. J. Respir. Crit. Care Med. 165:1497–1498 - PubMed

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