Campylobacter concisusis prevalent in the gastrointestinal tract of patients with microscopic colitis

Objectives Microscopic colitis (MC) is potentially induced by an inflammatory reaction to a luminal gut factor. The emerging pathogenCampylobacter concisusis associated with prolonged diarrhoea and subsequently increased risk of MC. We aimed to examine the prevalence ofC. concisusin clinical samples from MC patients, analyse the subtypes collagenous colitis (CC) and lymphocytic colitis (LC), and characteriseC. concisusisolates from MC patients by genomic sequencing. Methods Mucosal biopsies were collected by sigmoidoscopy in 55 MC patients (CCn = 34, LCn = 21). Saliva and faecal samples were also collected. A two-step cultivation method and PCR establishedC. concisusprevalence. Biopsy and faecal isolates were sequenced for genomic analysis. Results Cultivation revealedC. concisusin saliva 55/55, faeces 14/55 and biopsies 69/436, which was confirmed by PCR in faeces 28/55 and biopsies 215/430. Interestingly, biopsy prevalence was higher in CC patients than in LC patients both by cultivation (50/270 vs.19/166,p = .058) and by PCR (175/270 vs. 40/160,p < .0001). Long disease duration also affected biopsy prevalence both by cultivation 30/244 (<2 years) vs. 39/192 (>2 years) (p = .025) and by PCR 103/239 (<2 years) vs. 112/191 (>2 years) (p = .002). Genomic analysis on sixty biopsy and twenty faecal isolates revealed division into two clusters/genomospecies and a high presence of various, putative virulence genes (zot, exotoxin 9 andhcp). Conclusions Campylobacter concisuswas prevalent in MC patients. Interestingly, the biopsy prevalence differed in biopsies from CC and LC patients and with regard to disease duration. Further studies are needed to elucidate this possible association.