Abstract:

Objective: To evaluate the diagnostic value of rifampicin resistance real-time fluorescence quantitative nucleic acid amplification assay (GeneXpert MTB/RIF) in testing stool specimens for detecting intestinal tuberculosis. Methods: From January 2019 to December 2021, the stool samples of 538 patients with clinically suspected intestinal tuberculosis were collected from Beijing Chest Hospital, Capital Medical University. Fluorescent smear microscopy, BACTEC MGIT 960 liquid rapid growth culture, GeneXpert MTB/RIF detection were performed. At the same time, the whole blood T-cell spot test, enteroscopy and intestinal mucosal tissue pathology were performed to analyze the diagnostic efficacy of fecal samples in diagnosing intestinal tuberculosis by GeneXpert MTB/RIF. Results: Out of 538 patients suspected of intestinal tuberculosis, 189 were diagnosed as intestinal tuberculosis according to clinical diagnostic criteria, 349 were diagnosed as non intestinal tuberculosis (including ulcerative colitis, intestinal infection, gastrointestinal ulcer, malignant tumor, Crohn’s disease, etc.). With the clinical diagnostic criteria as the gold standard, the sensitivity and specificity of GeneXpert MTB/RIF test on stool samples were 77.2% (95%CI: 70.5%-82.9%) and 51.0% (95%CI: 45.6%-56.3%), respectively; The sensitivity and specificity of stool fluorescent smear microscopy were 23.3% (95%CI: 17.6%-30.1%) and 92.8% (95%CI: 89.5%-95.2%); The sensitivity and specificity of fecal liquid rapid growth culture were 29.1% (95%CI: 22.9%-36.2%) and 83.7% (95%CI: 79.3%-87.3%). Conclusion: In the diagnosis of intestinal tuberculosis, stool GeneXpert MTB/RIF test showed relatively high sensitivity for detecting Mycobacterium tuberculosis in clinical diagnosed patients who lack bacteriological diagnosis evidence, which could improve the diagnosis level of intestinal tuberculosis.

Key words: Tuberculosis, gastrointestinal, Feces, Molecular diagnostic techniques, Sensitivity and specificity