Multicenter evaluation of the acid-fast bacillus smear, mycobacterial culture, Xpert MTB/RIF assay, and adenosine deaminase for the diagnosis of tuberculous peritonitis in China.

Background: The aim of this study was to assess the validity of GeneXpert MTB/RIF (Xpert) and adenosine deaminase (ADA) in the diagnosis of tuberculous peritonitis (TBP).
Methods: The laboratory results of peritoneal effusion (PE) specimens from patients with symptoms suggestive of TBP, attending three TB specialized hospitals between January 2016 and December 2018, were included retrospectively. Clinically diagnosed TBP was set as the gold standard to evaluate the performance of these methods.
Results: In total, 191 individuals presenting with symptoms suggestive of TBP were included for analysis. The sensitivities of MGIT culture and Xpert were 17.2% and 18.3%, respectively. In addition, the TBP cases (69.8±6.0U/l) had higher amounts of ADA in their PE samples than the non-TBP cases (12.6±1.6U/l; p<0.01). Using a threshold of 31.5U/l to differentiate the TBP group from non-TBP group, the ADA assay provided a sensitivity of 89.6% and a specificity of 92.1%. The mean ADA concentration was significantly higher in bacteria-positive cases than in bacteria-negative cases (p<0.01).
Conclusions: In conclusion, the study data demonstrate the high sensitivity and specificity of the ADA test for the early diagnosis of TBP. In addition, the ADA concentration is directly correlated with the mycobacterial load.
(Copyright © 2019 The Author(s). Published by Elsevier Ltd.. All rights reserved.)