Effectiveness and safety of oral vancomycin in non-primary sclerosing cholangitis paediatric inflammatory bowel disease

Objectives: Oral vancomycin (OV) has limited usage in paediatric inflammatory bowel disease (PIBD) with reported efficacy in primary sclerosing cholangitis (PSC-PIBD), acute severe colitis as part of quadruple-antibiotic regimen, and very early-onset IBD. This study evaluates OV effectiveness and safety as a single-agent in non-PSC PIBD. Methods: This single-centre retrospective study included patients on OV for active disease or steroid/topical therapy dependency. Exclusion criteria were PSC diagnosis, Clostridioides difficile infection, induction treatment started <3 weeks prior, and OV as part of quadruple-antibiotic regimen. Disease activity was assessed at baseline, 1-, 3-, 6- and 12-months. OV was started at 250/125 mg (≥30/<30 kg), three or four times daily, and tapered in responders after ≥1 month. Results: Thirty-one patients (16 males; median age 15.1 years, IQR:11.7–16.6) were included: 23 ulcerative colitis (UC), 4 IBD-unclassified (IBDU) and 4 Crohn's disease. OV dosing was 17.5 mg/kg/day (IQR: 15.3–21.6) for 4 months (IQR: 1–9). Clinical and biochemical remission was achieved or maintained in 17/31 (55%), with 15/17 reducing/stopping other treatments and two remaining on OV monotherapy. Conversely, 14/31 (45%) discontinued OV due to non-response (11/14) or intolerance (3/14), the majority (11/14) within 1 month. Responders had lower baseline clinical disease activity and platelet count (p < 0.05). At 1-month faecal calprotectin dropped from 686 to 60 μg/g in responders (p = 0.001) but remained high in nonresponders. No serious adverse events occurred. Conclusion: OV was rapidly effective in 55% of PIBD cases, enabling 48% to reduce or stop other treatments. It proved most beneficial in mildly active UC/IBDU as an induction strategy plus a maintenance option for some, with a role in others in treatment de-escalation.