Enteric opportunistic infections in patients with inflammatory bowel disease receiving biologic therapies: a retrospective cohort study.

BACKGROUND

Biologic therapy has improved outcomes in inflammatory bowel disease (IBD) but may predispose patients to enteric opportunistic infections. Asian data comparing infection risk across biologic classes remain scarce. We therefore assessed the incidence of Clostridioides difficile infection (CDI), Clostridium innocuum (CI) infection, and cytomegalovirus (CMV) colitis in IBD patients treated with Vedolizumab (VDZ), anti-tumor necrosis factor agents (anti-TNF), or Ustekinumab (UST).

METHODS

This single‑center, retrospective cohort study included IBD patients who initiated VDZ, anti‑TNF (infliximab or adalimumab) or UST at Chang Gung IBD Center between January 2017 and December 2024. Opportunistic infection was defined as: (i) toxin‑gene PCR-positive CDI, (ii) CI isolated in stool/colonic culture, or (iii) CMV‑positive immunohistochemistry on intestinal biopsy. Incidence rates were expressed per 100 patient‑years. Infection‑free survival was compared with Kaplan-Meier analysis and log‑rank testing. Multivariable logistic regression identified independent predictors of CDI.

RESULTS

A total of 614 patients (377 Crohn's disease; 237 ulcerative colitis) contributed 941 patient‑years of follow‑up. The incidences per 100 patient-years were 3.51 for CDI, 0.85 for CI, and 3.30 for CMV colitis. CDI and CI risks were comparable across VDZ, anti‑TNF and UST cohorts. CMV colitis was significantly more common with anti‑TNF therapy (5.9%) than with VDZ (3.4%) or UST (0.5%) (p = 0.020). Independent predictors of CDI were an acute IBD flare (odds ratio [OR] 3.64; 95% confidence interval 1.91-6.91), concurrent CMV colitis (OR 6.34; 95% confidence interval 2.03-19.8) and CI infection (OR 7.79; 95% confidence interval 1.40-43.3).

CONCLUSION

VDZ and UST were not associated with excess CDI, CI or CMV risk, whereas anti‑TNF therapy conferred a higher burden of CMV colitis. Heightened infection surveillance is warranted during acute flares and refractory disease courses.