Cytomegalovirus Infection Is Associated with Increased Disease Activity and Worse Long-Term Course in Ulcerative Colitis.

Background: Human cytomegalovirus (CMV) infection is frequently detected in patients with ulcerative colitis (UC), particularly in severe or refractory disease. Its impact on disease activity, long-term course, and clinical outcomes remains controversial. Methods: In this retrospective single-center cohort study conducted at the University Hospital Münster (Germany), adult UC patients undergoing colonoscopy between May 2002 and May 2024 were included. CMV status was determined by tissue-based PCR from colonic biopsies at baseline colonoscopy (BL). Patients with at least one follow-up colonoscopy (FU) were analyzed. Clinical and endoscopic disease activity (total Mayo score [tMayo], endoscopic Mayo score [eMayo]), remission rates, treatment exposure, and outcomes were compared between patients with CMV-positive and CMV-negative biopsies at BL and FU. Results: A total of 181 UC patients were included (63 CMV-positive, 118 CMV-negative biopsies). At BL, CMV-positive patients had significantly higher endoscopic disease activity (eMayo, Conclusions: Molecular detection of CMV in the intestinal mucosa is associated with increased mucosal inflammation and a less favorable long-term disease course in UC, but has no effect on hard outcome parameters such as colectomy. Antiviral therapy has no effect on clinical outcome parameters. These findings indicate that further studies are needed to clarify the pathophysiological influences of CMV infection on disease course in ulcerative colitis and its impact on the efficacy of advanced therapies.