P922 Gut microbiome and mycobiome in inflammatory bowel disease patients with Clostridium difficile infection

Abstract

Abstract Background Clostridium difficile infection (CDI) is common in patients with inflammatory bowel disease (IBD) and has been reported as a risk factor for poor outcome. However, gut microbiome and mycobiome of IBD patients with CDI have been barely investigated. This study aimed to assess the gut microbiome and mycobiome in IBD patients with CDI. Methods We collected fecal samples from patients with IBD and concomitant CDI (IBD-CDI group, n=38), patients with IBD and no CDI (IBD-only group, n=91), and healthy subjects (HC, n=40). Patients characteristics including demographic data, disease severity, and medication history were collected. 16S rRNA sequencing, metagenomic sequencing, and untargeted metabolomic analysis were carried out in the samples. Results We found that the bacterial alpha diversity of the IBD-CDI group was lower than the IBD-only group and HC. And the bacterial and fungal beta diversity variations between IBD patients and HC were significant, regardless of CDI status. But the IBD-CDI group did not significantly cluster separately from the IBD-only group. Several bacterial taxa, including Ruminococcus gnavus, Clostridium innocuum, and Veillonella were overrepresented in the IBD-CDI group compared with IBD-only group and HC. Furthermore, IBD patients with CDI were distinguished from the IBD-only group and HC by several fungal taxa, including underrepresentation of Candida albicans, and overrepresentation of Saccharomyces cerevisiae, Eremothecium sinecaudum, Torulaspora delbrueckii, Grosmannia clavigera, and Eremothecium gossypii. The fungal-bacterial transkingdom network was altered in the IBD patients with CDI with a decreased network density. Notably, the relative abundance of Grosmannia clavigera was markedly higher in severe ulcerative colitis patients (defined by Truelove and Witts criteria and Mayo score). Besides, prior antibiotic exposure was associated with decreased biodiversity and increased dysbiosis. Functional differences in IBD patients with CDI include enrichment of branched-chain fatty acid biosynthesis, succinate fermentation to butanoate, peptidoglycan biosynthesis, and tetrahydrofolate biosynthesis. The metabolomic data indicated that the differential metabolites were predominantly involved in amino sugar and nucleotide sugar metabolism, fatty acid metabolism, porphyrin and chlorophyll metabolism, and neomycin, kanamycin and gentamicin biosynthesis. Conclusion IBD patients with CDI had pronounced microbial dysbiosis. Gut micro-ecological changes and interkingdom crosstalk in IBD patients with CDI might provide insight into the pathological process and potential strategies for diagnosis and treatment in this subset of patients.