Characterization of the gut microbiota in an Italian cohort of IBS patients. GUT MICROBIOTA COMPOSITION AND CHARACTERIZATION OF CULTIVABLE FUNGAL ISOLATES IN IBS PATIENTS

in Irritable Bowel Syndrome (IBS) studies conducted so far have been focused on gut microbial dysbiosis. Limited evidences showed a potential involvement of fungal communities in IBS.Here, the bacterial and fungal gut microbiota of a cohort of IBS patients have been characterized and compared with healthy subjects (HS). We performed a preliminary analysis on fecal samples by ARDRA profiles in order to evaluate dissimilarity of gut microbiota composition in IBS patients with that of health subjects (HS). Microbial profiles, using NGS, showed enrichment of bacterial species involved in gut inflammation, such as Enterobacteriaceae, Streptococcus, Fusobacteria, Gemella and Rothia, and a depletion of beneficial bacteria such as Roseburia and Faecalibacterium. In addition, by qPCR we observed an increase in the absolute abundance of Enterobacteriaceae and a decrease of Bifidobacterium in IBS vs HS. IBS microbial profiles differ also for constipation and not-constipation symptoms.Fungal cultivable analysis showed a higher abundance of isolates in IBS vs HS, with an enrichment of Candida albicans and C. parapsilosis. RAPD profile analysis of C. albicans and C. parapsilosis showed genotypical differences among IBS and HS isolates, with a clonal expansion of Candida isolates in IBS. Finally, we observed that IBS fungal isolates showed different phenotypical features from HS isolates. Our results confirmed the presence of an altered microbial community in IBS, with enrichment of bacterial taxa involved in inflammatory phenomena and reduction of anti-inflammatory microbes. By the fungal community counterpart, C. albicans and C. parapsilosis isolates from IBS are both phenotypically and genotypically different from isolates of HS, suggesting a different ability to gut adaptation. Finally, our results highlighted on one hand the importance of understanding the role of fungal dysbiosis in IBS pathophysiology, and on the other hand evaluating of microbial dysbiosis as responsible of intestinal fungal population overgrowth.