High risk of microscopic colitis after <i>Campylobacter concisus</i> infection: population-based cohort study.

Abstract

Microscopic colitis (MC) encompasses the two histopathological distinct entities of collagenous colitis (CC) and lymphocytic colitis (LC). In this Danish population-based cohort study, we examined the risk of MC following stool culture with <i>Campylobacter concisus</i>, <i>C. jejuni</i>, non-typhoidal <i>Salmonella</i> or a culture-negative stool test. We identified patients with a first-time positive stool culture with <i>C. concisus</i>, <i>C. jejuni</i>, non-typhoidal <i>Salmonella</i> or negative stool test, from 2009 through 2013 in North Denmark Region, Denmark, and matched each with 10 population comparisons. All subjects were followed up until 1 March 2018 using Systematised Nomenclature of Medicine codes from The Danish Pathology Register for incident diagnoses of CC and LC. We computed risk and adjusted HRs with 95% CIs for MC among patients and comparisons. We identified 962 patients with <i>C. concisus</i>, 1725 with <i>C. jejuni</i>, 446 with <i>Salmonella</i> and 11 825 patients with culture-negative stools. The MC risk and HR versus comparisons were high for patients with <i>C. concisus</i> (risk 6.2%, HR 32.4 (95% CI 18.9 to 55.6)), less for <i>C. jejuni</i> (risk 0.6%, HR 3.7 (95% CI 1.8 to 7.7)), low for <i>Salmonella</i> (risk 0.4%, HR 2.2 (95% CI 0.5 to 10.8)) and for patients with negative stool testing (risk 3.3%, HR 19.6 (95% CI 16.4 to 23.4)). After exclusion of the first year of follow-up, the HRs were 9.3 (95% CI 4.1 to 20.1), 2.2 (95% CI 0.9 to 5.4), 1.3 (95% CI 0.2 to 11.1) and 5.6 (95% CI 4.6 to 7.2), respectively. A high risk of MC was observed following <i>C. concisus</i> in stools. Further studies are needed to elucidate any underlying biological mechanisms.