Abstract
Background
Xpert™ MTB/Rif is a multiplex hemi-nested real-time PCR-based assay to detect presence of M. tuberculosis within 2 hours of sample collection. The present study aimed at assessing efficacy of Xpert™ MTB/Rif assay for diagnosing peritoneal tuberculosis.
Methods
Patients with exudative ascites, fluid negative for acid-fast bacilli on auramine O fluorescence staining and unyielding fluid cytology for malignant cells, were included. Ultrasound-guided omental biopsy samples were obtained in all. Xpert™ MTB/Rif assay on tissue samples was assessed against a composite “reference” standard for diagnosis of peritoneal tuberculosis, defined as presence of any of the three-culture showing M tuberculosis, granulomatous inflammation on histology or resolution of ascites with 2 months of antitubercular therapy.
Results
During January 2012–July 2013, 28 patients (age:43 ± 15 years; mean ± SD; male:20) were recruited. Serum ascitic albumin gradient was <1.1 in all except in four patients with underlying cirrhosis. Twenty-one of the 28 patients had peritoneal TB as diagnosed by composite reference standard (histology:18; culture:4; treatment response:3). Seven patients (25 %) had an alternative diagnosis (metastatic carcinoma 2, adenocarcinoma 2, mesothelioma 2, and systemic lupus erythematous 1). Xpert™ MTB/Rif assay was positive in 4/21 patients with peritoneal tuberculosis and in none of the 7 patients with alternative diagnosis. Thus, sensitivity, specificity, positive, and negative predictive values for tissue Xpert™ MTB/Rif assay in diagnosing peritoneal tuberculosis were 19 % (95 % C.I: 6 % to 42 %), 100 % (95 % C.I: 59 % to 100 %), 100 % (40 % to 100 %), and 29 % (95 % C.I: 13 % to 51 %), respectively.
Interpretation and conclusion
Tissue Xpert™ MTB/Rif assay was of limited use in diagnosing peritoneal tuberculosis.
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The study was performed in a manner to conform with the Helsinki Declaration of 1975, as revised in 2000 and 2008, concerning human and animal rights, and the authors followed the policy concerning informed consent as shown on Springer.com.
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CB, JSM, DB, SBS, SG, BR, AG, and CE declare that they have no competing interests.
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Bera, C., Michael, J.S., Burad, D. et al. Tissue Xpert™ MTB/Rif assay is of limited use in diagnosing peritoneal tuberculosis in patients with exudative ascites. Indian J Gastroenterol 34, 395–398 (2015). https://doi.org/10.1007/s12664-015-0599-7
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DOI: https://doi.org/10.1007/s12664-015-0599-7