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Year : 2018  |  Volume : 36  |  Issue : 3  |  Page : 357--363

Diagnostic accuracy of Xpert MTB/RIF assay in extrapulmonary tuberculosis

Sheetal Bankar1, Reena Set1, Disha Sharma1, Daksha Shah2, Jayanthi Shastri1 
1 Department of Microbiology, T.N. Medical College and B Y L Nair Ch. Hospital, Mumbai, Maharashtra, India
2 City TB Officer, Mumbai District Tuberculosis Control Society, Mumbai, Maharashtra, India

Correspondence Address:
Dr. Reena Set
Department of Microbiology, T.N. Medical College and B Y L Nair Ch. Hospital, Mumbai, Maharashtra
India

Introduction: The WHO endorsed Xpert Mycobacterium tuberculosis/rifampicin (MTB/RIF) assay, has been evaluated for pulmonary TB in a number of studies but very few have investigated it for extrapulmonary specimens. The present study evaluates the performance of Xpert MTB/RIF assay in the diagnosis of extrapulmonary TB (EPTB). Aim and Objectives: The aim of the study is to determine sensitivity and specificity of Xpert MTB/RIF assay for diagnosis of EPTB and RIF resistance in comparison to culture on Lowenstein–Jensen (LJ) medium and proportion method (PM), respectively. Materials and Methods: A total of 738 specimens from clinically suspected cases of EPTB were subjected to Ziehl–Neelsen staining, Xpert MTB/RIF assay and culture on LJ medium. PM was done on MTB isolates. Results: The sensitivity, specificity of Xpert MTB/RIF assay for diagnosis of EPTB were 84.91% (95% confidence interval [CI] 72.41%–93.25%) and 86.72% (95% CI 83.94%–89.17%) and for RIF resistance detection were 60.00% (95% CI 32.29%–83.66%) and 94.74% (95% CI 73.97%–99.87%), respectively. Among culture-positive cases, the sensitivity of Xpert MTB/RIF assay was 94.12% in smear positive and 80.56% in smear-negative cases. Xpert MTB/RIF showed maximum sensitivity of MTB detection from lymph node specimens (100% [95% CI 54.07%–100.00%]) and other body fluids (100% [95% CI 15.81%–100.00%]). Conclusion: The present study establishes Xpert MTB/RIF assay as a promising tool in the rapid diagnosis of EPTB and detection of RIF resistance.

How to cite this article:
Bankar S, Set R, Sharma D, Shah D, Shastri J. Diagnostic accuracy of Xpert MTB/RIF assay in extrapulmonary tuberculosis.Indian J Med Microbiol 2018;36:357-363

How to cite this URL:
Bankar S, Set R, Sharma D, Shah D, Shastri J. Diagnostic accuracy of Xpert MTB/RIF assay in extrapulmonary tuberculosis. Indian J Med Microbiol [serial online] 2018 [cited 2020 Aug 10 ];36:357-363
Available from: http://www.ijmm.org/article.asp?issn=0255-0857;year=2018;volume=36;issue=3;spage=357;epage=363;aulast=Bankar;type=0