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* = Presenting author

P754 IBD phenotypes differ in gut mycobiota composition

P. Drastich1, L. Bajer*1, K. Klimesova2, M. Kostovcik2, M. Kverka2, J. Brezina1, J. Spicak1

1Institute for Clinical and Experimental Medicine, Hepatogastroenterology, Prague, Czech Republic, 2Institute for Microbiology of the CAS, Prague, Czech Republic

Background

Inflammatory bowel disease (IBD) (Crohn’s disease [CD] and ulcerative colitis [UC]), is a chronic idiopathic disorder of gastrointestinal tract. Although its pathogenesis is not completely understood, the inflammation in IBD is a result of an aberrant immune response to commensal microbiota in genetically susceptible individuals. Because there is a marked association of CD with gut fungal microbiota (mycobiota) we analysed its composition in patients with CD, UC and in healthy controls.

Methods

We obtained stool samples from 9 CD patients, 7 UC patients, and 3 healthy controls, and extracted DNA using repeated bead-beating technique. Next, we analysed mycobiota composition by sequencing the internal transcribed spacer (ITS2) region of fungal DNA using Illumina MiSeq. The data were processed using standard Qiime pipeline, and the mycobiome alpha (Simpson’s evenness index) and beta diversity (binary Jaccard metrics) were calculated.

Figure 1.

Results

Number of detected fungal OTUs was not significantly different amongst groups (healthy controls = 4.7 ± 0.6, CD = 5.9 ± 3.1 and UC = 7.6 ± 2.5). Either form of IBD clearly increased mycobiome variability, as documented by an increase in alpha diversity in CD and UC. All healthy individuals have similar fungal communities, dominated by well adapted natural symbionts such as orders Saccharomycetales and Onygenales. In IBD, these communities were disrupted, and several other fungi were acquired from the environment. These major qualitative differences are well documented by tight clustering pattern of all 3 groups, as measured by binary Jaccard metrics. This was caused mainly by appearance of Davidiellaceae family and decrease in diversity within order Saccharomycetales in IBD patients.

Conclusion

These preliminary data show that gut mycobiota has significant pattern associated with health and disease. The high variability and presence of acquired fungi suggest that disrupted gut microbial ecology in IBD support transient fungal communities. Larger groups and more experiments are needed to confirm these interesting findings and to assess their medical relevance.