Campylobacter spp. infection and subsequent clinical outcomes in patients with inflammatory bowel disease

Campylobacter species (spp) infection has been linked to the development of inflammatory bowel disease (IBD), but its impact on the clinical course of patients with established IBD remains unclear.

We conducted a single-centre retrospective cohort study including all stool samples positive for Campylobacter spp. between 2010 and 2024. Patients aged ≥14 years with IBD and microbiologically confirmed Campylobacter infection were included. Infected patients were matched 1:2 with uninfected IBD controls using propensity score matching. The primary outcome was a composite adverse clinical course within 12 months, defined as IBD-related hospitalization, treatment intensification, surgery, or death.

Among 2,662 stool cultures positive for Campylobacter spp., 43 corresponded to patients with IBD ≥14 years (20 CD, 23 UC); one UC patient with prior colectomy was excluded, yielding 42 infected IBD patients. Campylobacter-positive stool cultures were more commonly identified among patients with IBD than in the general population (1.656% vs. 0.576%; RR 2.87, 95% CI 2.13-3.87; p<0.0001). However, this comparison was descriptive and cannot establish a true increased infection risk. After matching, 126 patients were analyzed. In an exploratory Cox proportional hazards model performed in the matched IBD cohort and stratified by IBD subtype, Campylobacter spp. infection was associated with shorter time to the primary composite endpoint (HR 4.49, 95% CI 1.90-10.61; p<0.001). Subgroup analyses in CD and UC showed directionally consistent findings but were limited by small event numbers and wide confidence intervals. In CD, Campylobacter infection was associated with a higher frequency of flare (25.0% vs. 5.0%; p=0.036) and treatment intensification (35% vs. 7.5%; p=0.012). In UC, infection was associated with increased risk of flare (31.8% vs. 9.1%; p=0.033), while differences in hospital admission and treatment intensification did not reach statistical significance.

In this single-centre retrospective matched cohort study, microbiologically confirmed Campylobacter spp. infection in patients with established IBD was associated with subsequent IBD flare and need for treatment escalation within the first 12 months. Given the retrospective design, limited event numbers, residual confounding, and potential ascertainment bias, these findings should be considered exploratory.