Fungal Microbiota Composition in Inflammatory Bowel Disease Patients: Characterization in Different Phenotypes and Correlation With Clinical Activity and Disease Course.

Background: There is growing evidence of the role of the mycobiome in inflammatory bowel disease (IBD). Variations within phenotypes and activity and with prognosis have been poorly studied.

Methods: A total of 111 individuals were prospectively enrolled: 89 IBD patients (52 ulcerative colitis and 37 Crohn's disease [CD]) and 22 healthy individuals. Disease characteristics were collected and a fecal calprotectin >100 μg/mg was considered indicative of activity. A subset of patients was followed for 6 ± 2 years. Disease course was designated as either complicated or uncomplicated based on the need of intensified medication and/or surgery. ITS sequencing was performed targeting the ITS1 region.

Results: We found lower Ascomycota/Basidiomycota ratio in IBD. Patients showed a marked increase in Candida dublinensis and Ca albicans and were depleted of Aspergillus rubrobrunneus and Penicillium brevicompactum (P ≤ .001) Saccharomyces was predominant in total colitis and Penicillium in proctitis. Several Penicillium species were depleted in total colitis vs proctitis. Ileal CD patients were enriched in Debaromyces hansenii and depleted of Ca tropicalis (P ≤ .001). Ca albicans was overrepresented in inflammatory (B1) vs fibrostenosing (B2) CD. Ca dublinensis was more abundant in active patients and correlated positively with fecal calprotectin and neutrophil gelatinase-associated lipocalin, while S pastorianus correlated inversely with activity. Ca sake was associated with complicated disease and increased abundance of Cryptococcus carnescens with the need for surgery in CD.

Conclusions: This study shows important differences in the mycobiome in IBD and within phenotypes. Selected fungal species were associated with complicated disease and the need of surgery in CD. This work adds to our understanding of the role of fungi in IBD, with potential clinical implications.