PT - JOURNAL ARTICLE AU - Kathleen Machiels AU - Marie Joossens AU - João Sabino AU - Vicky De Preter AU - Ingrid Arijs AU - Venessa Eeckhaut AU - Vera Ballet AU - Karolien Claes AU - Filip Van Immerseel AU - Kristin Verbeke AU - Marc Ferrante AU - Jan Verhaegen AU - Paul Rutgeerts AU - Séverine Vermeire TI - A decrease of the butyrate-producing species <em>Roseburia hominis</em> and <em>Faecalibacterium prausnitzii</em> defines dysbiosis in patients with ulcerative colitis AID - 10.1136/gutjnl-2013-304833 DP - 2014 Aug 01 TA - Gut PG - 1275--1283 VI - 63 IP - 8 4099 - http://gut.bmj.com/content/63/8/1275.short 4100 - http://gut.bmj.com/content/63/8/1275.full SO - Gut2014 Aug 01; 63 AB - Objective Bacteria play an important role in the onset and perpetuation of intestinal inflammation in inflammatory bowel disease (IBD). Unlike in Crohn's disease (CD), in which dysbiosis has been better characterised, in ulcerative colitis (UC), only small cohorts have been studied and showed conflicting data. Therefore, we evaluated in a large cohort if the microbial signature described in CD is also present in UC, and if we could characterise predominant dysbiosis in UC. To assess the functional impact of dysbiosis, we quantified the bacterial metabolites. Design The predominant microbiota from 127 UC patients and 87 age and sex-matched controls was analysed using denaturing gradient gel electrophoresis (DGGE) analysis. Differences were quantitatively validated using real-time PCR. Metabolites were quantified using gas chromatography–mass spectrometry. Results Based on DGGE analysis, the microbial signature previously described in CD was not present in UC. Real-time PCR analysis revealed a lower abundance of Roseburia hominis (p&lt;0.0001) and Faecalibacterium prausnitzii (p&lt;0.0001) in UC patients compared to controls. Both species showed an inverse correlation with disease activity. Short-chain fatty acids (SCFA) were reduced in UC patients (p=0.014), but no direct correlation between SCFA and the identified bacteria was found. Conclusions The composition of the fecal microbiota of UC patients differs from that of healthy individuals: we found a reduction in R hominis and F prausnitzii, both well-known butyrate-producing bacteria of the Firmicutes phylum. These results underscore the importance of dysbiosis in IBD but suggest that different bacterial species contribute to the pathogenesis of UC and CD.