Application value of tissue tuberculosis antigen combined with Xpert MTB/RIF detection in differential diagnosis of intestinal tuberculosis and Crohn’s disease

Abstract

Background: The purpose of this study was to evaluate the value of Xpert MTB/RIF detection and tuberculosis antigen detection of Mycobacterium tuberculosis (MTB) in intestinal tissues for differentiating intestinal tuberculosis (ITB) from Crohn’s disease (CD). Materials and Methods: A total of 110 patients who were clinically diagnosed with CD or ITB between January 2016 and March 2018 were initially enrolled in this study. The patients were monitored and their clinical, endoscopic and histopathological characteristics were followed up until their final diagnosis was clearly made. Several specimens of intestinal tissue from endoscopic biopsy or surgical excision were collected. One piece was used as paraffin specimen, and the other two pieces were used for MTB culture and Xpert MTB/RIF detection, respectively. Four antigens (38KDa protein, ESAT-6 protein, MPT64, Ag85 complex) of MTB in intestinal tissue were detected by immunohistochemistry. Results: A total of 42 cases of intestinal tuberculosis and 46 cases of CD were included in the experimental analysis. Perianal lesions and longitudinal ulcers were more common in CD patients (p < 0.05), while caseous granuloma and annular ulcers were more common in ITB patients (P < 0.05). The positive rate of M. tuberculosis detected by Xpert MTB/RIF in intestinal tissue samples of ITB patients was 33.33%, which was significantly higher compared to CD patients (p < 0.05) and compared to acid-fast staining smears (9.52%) (p < 0.05). The positive MPT64 expression rate in patients with intestinal tuberculosis was 40.48%, which was significantly higher than that observed in CD patients, which was 19.56% (X2=4.61, p<0.05). Conclusions: The detection of Xpert MTB/RIF in intestinal tissue was conducive to the quick and early diagnosis of intestinal tuberculosis. Xpert MTB/RIF and MPT64 antigen in intestinal tissues had certain value in the differential diagnosis of intestinal tuberculosis and Crohn’s disease. The combination of these two methods could improve detection sensitivity.