Proximally dominant inflammation at colonoscopy predicts pan-colonic histological remission following oral vancomycin therapy in pediatric ulcerative colitis

Background Oral vancomycin therapy (OVT) induces histological remission in children with ulcerative colitis (UC) showing primary sclerosing cholangitis (PSC)-associated features (proximally dominant or patchy inflammation, backwash ileitis, or rectal sparing). However, predictors of response and optimal treatment duration remain unclear. Aim To evaluate segmental colonoscopy outcomes across various OVT durations. Methods Children with active UC receiving OVT for ≥3 months were retrospectively identified. Pre-post-OVT colonoscopies were available for 38 children, 4 had repeated examination after relapsing and re-commencing OVT, totaling 42 colonoscopy pairs. Results Pre-OVT colonoscopies showed 19 proximally dominant inflammation (more severe gradient proximal to hepatic flexure), 18 pancolitis with backwash ileitis or rectal sparing, 3 patchy colitis, and 2 distal colitis. Within 5.7 (IQR 3.5–7.5) months after OVT, follow-up colonoscopy showed mucosal healing (Mayo 0) in 27/42. Pan-colonic histological remission was achieved in 23/42, more frequently in proximally dominant colitis than in other UC types (aOR 7.50, 95% CI 1.22–46.3). Remission rate was higher after ≥4 months of therapy compared with shorter durations (aOR 7.12, 95% CI 1.14–44.7). Conclusions Over half of post‑OVT colonoscopies showed pan‑colonic histological remission, particularly in proximally dominant UC. Treating for ≥4 months further improved outcomes, helping identify which patients may benefit from OVT.