The role of microaerophilic colonic mucosal bacteria in de novo paediatric inflammatory bowel disease

Abstract

Introduction species can initiate animal colitis similar to human ulcerative colitis (UC). has been linked to paediatric Crohn's disease (CD). Microaerophilic organisms such as and may be involved in the initiation of IBD. Methods Paediatric patients undergoing colonoscopy were recruited to two groups: those with a new diagnosis of IBD at their first presentation and controls with a macroscopically normal colon and no evidence of IBD on biopsy. All subjects were free from systemic antibiotics, steroids and immunosuppression for 3 months. 24 IBD patients and 26 controls were studied. The IBD cohort comprised 12 (50%) CD, 8 (33.3%) UC and 4 (16.7%) IBD unspecified (IBD-U) patients. 15 (62.5%) of the IBD and 20 (77.8%) of the control groups were male with median ages of 12.4 and 11.0 years, respectively. 5–6 Colonic mucosal biopsies were taken: in controls largely from the sigmoid/rectum and in IBD from the most distal inflamed site. 3 biopsies were stored at −80°C for subsequent DNA extraction and PCR. 1–2 biopsies were used for culture. 5 selective plates were used alongside blood agar. Cultures were incubated in microaerophilic conditions (Anoxomat) at 37°C. Plates were reviewed twice weekly for up to 1 month. Isolates deemed Gram-negative and microaerophilic underwent PCR of the 16S rRNA gene for phylogenetic identification. Results No were cultured. 3 spp. were isolated: from a subject with CD, and from controls. was isolated from 13 subjects: 8 controls and 5 IBD. All biopsies were positive for bacterial DNA with universal primers. Nested PCR for genus was positive in 5 (10%) subjects, comprising 3 (12.5%) IBD and 2 (7.7%) controls. PCR for genus was positive in 38 (76%) subjects, comprising 19 (79.2%) IBD and 19 (73.1%) controls. Nested PCR for was positive in 25 (50%) subjects, comprising 14 (58.3%) IBD (8/12 CD, 3/8 UC and 3/4 IBD-U) and 11 (42.3%) controls. In response to frequent isolation of the organism, PCR for was positive in 48 (96%) subjects, comprising 23 (95.8%) IBD and 25 (96.2%) controls. Conclusion spp. and are commonly identified in the paediatric colon. appears more prevalent in CD although this was not significant. spp. are uncommon. PCR and culture methodology have revealed no significant distinction between the microaerophilic microbiota of paediatric IBD versus controls. It is unlikely that these organisms have a role in the initiation of paediatric IBD. [ABSTRACT FROM PUBLISHER]