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. 2017 Apr;15(2):187-194.
doi: 10.5217/ir.2017.15.2.187. Epub 2017 Apr 27.

Evaluation of Xpert MTB/RIF assay performance in the diagnosis of abdominal tuberculosis

Suraj Kumar  1 , Sawan Bopanna  1 , Saurabh Kedia  1 , Pratap Mouli  1 , Rajan Dhingra  1 , Rajesh Padhan  1 , Mikashmi Kohli  2 , Jigyasa Chaubey  2 , Rohini Sharma  2 , Prasenjit Das  3 , S Dattagupta  3 , Govind Makharia  1 , S K Sharma  2 , Vineet Ahuja  1
Affiliations

Evaluation of Xpert MTB/RIF assay performance in the diagnosis of abdominal tuberculosis

Suraj Kumar et al. Intest Res. 2017 Apr.

Abstract

Background/aims: The use of genetic probes for the diagnosis of pulmonary tuberculosis (TB) has been well described. However, the role of these assays in the diagnosis of intestinal tuberculosis is unclear. We therefore assessed the diagnostic utility of the Xpert Mycobacterium tuberculosis/rifampicin (MTB/RIF) assay, and estimated the prevalence of multidrug-resistant (MDR) TB in the Indian population.

Methods: Of 99 patients recruited, 37 had intestinal TB; two control groups comprised 43 with Crohn's disease (CD) and 19 with irritable bowel syndrome. Colonoscopy was performed before starting any therapy; mucosal biopsies were subjected to histopathology, acid-fast bacilli staining, Lowenstein-Jensen culture, and nucleic acid amplification testing using the Xpert MTB/RIF assay. Patients were followed up for 6 months to confirm the diagnosis and response to therapy. A composite reference standard was used for diagnosis of TB and assessment of the diagnostic utility of the Xpert MTB/RIF assay.

Results: Of 37 intestinal TB patients, the Xpert MTB/RIF assay was positive in three of 37 (8.1%), but none had MDR-TB. The sensitivity, specificity, positive predictive value, and negative predictive value of the Xpert MTB/RIF assay was 8.1%, 100%, 100%, and, 64.2%, respectively.

Conclusions: The Xpert MTB/RIF assay has low sensitivity but high specificity for intestinal TB, and may be helpful in endemic tuberculosis areas, when clinicians are faced with difficulty differentiating TB and CD. Based on the Xpert MTB/RIF assay, the prevalence of intestinal MDR-TB is low in the Indian population.

Keywords: Crohn disease; Tuberculosis, multidrug-resistant; Xpert MTB/RIF assay.

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Conflict of interest statement

Conflict of interest: None.

Figures

Fig. 1
Fig. 1. Flow chart showing patient recruitment. TB, tuberculosis; ATT, antitubercular therapy; Misc, miscellaneous; ITB, intestinal tuberculosis.
See this image and copyright information in PMC

References

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