P883 Faecal microbiota composition in adult, newly diagnosed, treatment-naïve IBD patients

Abstract

The intestine represents an interface where host tissues come in contact with microbiota in a balanced state of homeostasis. Mounting knowledge on gut microbiota led to many important findings associating the composition of bacterial taxa in the human gastrointestinal tract with many human disorders including the inflammatory bowel disease (IBD). ulcerative colitis (UC) and Crohn’s disease (CD) as the most prevalent forms of IBD are characterised by chronic relapsing inflammation affecting the intestinal mucosa and although the aetiology of both diseases is unknown, there is increasing evidence that intestinal microbial dysbiosis has a role in the pathogenesis. One of the main objectives of our study is to investigate the contribution of the faecal and intestinal microbiota composition to the disease specific phenotype. Faecal samples are being collected from adult, newly diagnosed, treatment-naïve IBD patients and controls with Irritable Bowel Syndrome (IBS) using OMNIgene. Gut collection system. The composition of gut microbiota from faeces was determined by amplification and sequencing of bacterial 16S rRNA gene using Illumina MiSeq. Raw sequencing files were processed using QIIME pipeline and Operational Taxonomic Units (OTUs) were assigned using the vsearch algorithm and PyNast alignment against the GreenGenes database (version 13_8, May 2013). Relative abundance proportions were analysed using two-way ANOVA with Bonferroni multiple comparisons test (significant if p < 0.05). Relative abundance data from 58 patients suggested that there were differences between groups already at the phylum level, namely there was a significant decrease of Bacteroidetes in CD group. Moreover, the statistical significance was observed between groups for Bacteroides (IBS>CD), Prevotella (CD < IBS < UC), Coprococcus (CD > UC) and Streptococcus (UC>CD>IBS) genera. Preliminary results of our study demonstrated clear differences in faecal bacterial populations between adult, newly diagnosed, treatment-naïve IBD and IBS patients.