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.