Xpert MTB/RIF Test in Differential Diagnosis of Intestinal Tuberculosis and Crohn’s Disease
AIBD 2023
Background:
Tuberculosis (TB) remains a persistent global health challenge, affecting approximately 10 million individuals worldwide. In Latin America, TB continues to pose a significant burden, with Brazil ranking among the top 30 countries with the highest TB incidence. Of particular concern is extrapulmonary TB, comprising about 15% of all TB cases, with abdominal tuberculosis being a prevalent form. This abstract aims to highlight the pivotal role of the Xpert MTB/RIF test in the detection of intestinal TB (ITB) and disseminate this knowledge to IBD specialists.
Results:
Case 1: A 53-year-old female presented with chronic diarrhea and mucus over the past year. Physical examination revealed tenderness in the right lower quadrant. She had latent TB, a normal chest CT, and elevated fecal calprotectin levels (552 mcg/g). Colonoscopy identified a 25 mm ulcer near the ileocecal valve. An anatomopathological examination confirmed granulomatous colitis negative for mycobacterium tuberculosis (MT). The Xpert MTB/RIF test of the colonoscopy biopsies detected MT DNA. Case 2: A 56-year-old female patient had a history of spontaneous abdominal purulent drainage dating back to 2008. Subsequent imaging examinations revealed an enterocutaneous fistula, leading to a laparotomy with the creation of a sigmoid colostomy. Subsequent colonoscopy and imaging studies indicated the recurrence of an enterocutaneous fistula. Biopsies were negative for tuberculosis except those from the cutaneous fistula tract, which Xpert MTB/RIF test yielded a positive result. Case 3: A 69-year-old female complained of year-long abdominal pain and diarrhea. Initial colonoscopy revealed cecal ulcers with granulomas. Initially diagnosed as Crohn’s disease, remained years with sulfasalazine with a compromised quality of life. After a new colonoscopy, Xpert MTB/RIF revealed I-TB. Case 4: A 20-year-old female with three months of watery diarrhea, abdominal pain, and a 15 kg weight loss. Colonoscopy revealed serpiginous ulcers in the right colon negative for infective disorders. Infliximab was initiated after a Crohn’s disease diagnosis after a negative Tuberculin skin test (0 mm). Patient complicated with a pulmonary sepsis after the first dose. During hospitalization, colonoscopy was repeated with a positive Xpert MTB/RIF in the rectum and sigmoid (in a normal macroscopic area of colonoscopy). All four patients exhibited mucosal healing in subsequent colonoscopy following TB treatment.
Discussion:
Colonoscopy is an important exam for the differential diagnosis of ITB and Crohn’s disease (CD). ITB most frequently affects the ileocecal region and the ascending colon while the presence of aphthous erosions, cobblestone appearance, raised lesions and longitudinal ulcers in other sites are more suggestive of CD. Xpert-MTB/RIF test has been described in literature with a specificity of almost 100% although many experts to not know about this test.
Conclusions:
Diagnosing intestinal TB remains a challenge. Recent research suggests that GeneXpert-MTB/RIF can enhance the detection of intestinal TB. Therefore, combining these methods may enhance ITB detection capabilities. However, further validation is needed for this diagnostic approach in the context of intestinal TB.
