Risk of inflammatory bowel disease after Campylobacter jejuni and Campylobacter concisus infection: a population-based cohort study

Objectives: In this population-based cohort study, we aimed to examine the risk of IBD following a positive stool culture with Campylobacter jejuni or Campylobacter concisus, as well as following culture-negative stool testing. Materials and methods: Patients with a first-time positive stool culture with C. jejuni or C. concisus, as well as negative stool testing, from 2009 through 2013 in North Denmark Region, Denmark, were identified. Patients diagnosed with IBD during follow-up (to 1 March 2018) were identified using national registries. For each case, we selected ten population comparisons matched by age, gender, and calendar-time. Results: We identified 1693 patients with C. jejuni, 910 C. concisus-positive patients, and 11,383 patients with culture-negative stools. During the first year of follow-up C. jejuni-positive patients had higher risk of IBD (HR 2.2, 95% CI 1.3-3.7) compared to population comparisons, but not after exclusion of the first year (HR 1.1, 95% CI 0.5-2.3). Campylobacter concisus-positive patients and culture-negative patients had similar risk of IBD (HR 12.9, 95% CI 7.2-22.9 and HR 8.7, 95% CI 7.5-10.2), during the first year, which decreased to (HR 3.3, 95% CI 1.3-8.5 and HR 3.2, 95% CI 2.6-4.0) after exclusion of the first year. Conclusions: This study does not support exposure of C. jejuni or C. concisus infection as a causal trigger in subsequent development of IBD, since culture-negative patients had similar risk for IBD on long term follow-up. Additional studies including C. concisus exposures for an evaluation of the specific risk of IBD are needed.