Microbiota Of Ulcerative Colitis Patients Research Articles

Characteristics of Mucosa-Associated Microbiota in Ulcerative Colitis Patients with 5-Aminosalicylic Acid Intolerance.

5-Aminosalicylic acid (5-ASA) is a first-line therapy for ulcerative colitis (UC). This study examined the mucosa-associated microbiota (MAM) in UC patients, distinguishing between those who were 5-ASA tolerant and intolerant. Brushing samples were collected from the sigmoid and ileal end of patients with UC during endoscopic procedures. The samples were profiled by using the Illumina MiSeq platform. The V3-V4 regions of the 16S rRNA gene (460 bp) were amplified by using tailed PCR. A total of 15 patients with 5-ASA intolerance, 38 patients with 5-ASA tolerance, and 19 healthy controls were recruited in this study. The α-diversity indices were remarkably different among the three groups in the ileum mucosa but not in the sigmoid colon. In the ileum mucosa, Alistipes, Ruminococcaceae, and Odoribacter were less abundant in the 5-ASA-intolerant group than in the control and 5-ASA-tolerant groups. On the contrary, Merdibacter, Brevundimonas, and Porphyromonas were more abundant in the 5-ASA-intolerant group than in other groups. The present study showed that the changes in MAM were characterized by a decrease in mucoprotective bacteria rather than an increase in harmful bacteria.

Taxonomic and phenotypic analysis of bifidobacteria isolated from IBD patients as potential probiotic strains

BackgroundInflammatory Bowel Diseases (IBD) are a major public health issue with unclear aetiology. Changes in the composition and functionality of the intestinal microbiota are associated with these pathologies, including the depletion of strict anaerobes such as Feacalibacterium prausnitzii. Less evidence is observed for depletion in other anaerobes, among which bifidobacteria. This study characterized the taxonomic and functional diversity of bifidobacteria isolated from the human intestinal microbiota in active and non-active IBD patients by a culturomics approach and evaluated if these bifidobacteria might be used as probiotics for gut health.ResultsA total of 341 bifidobacteria were isolated from the intestinal microbiota of IBD patients (52 Crohn’s disease and 26 ulcerative colitis patients), with a high proportion of Bifidobacterium dentium strains (28% of isolated bifidobacteria). In ulcerative colitis, the major species identified was B. dentium (39% of isolated bifidobacteria), in active and non-active ulcerative colitis. In Crohn’s disease, B. adolescentis was the major species isolated from non-active patients (40%), while similar amounts of B. dentium and B. adolescentis were found in active Crohn’s disease patients. The relative abundance of B. dentium was increased with age, both in Crohn’s disease and ulcerative colitis and active and non-active IBD patients. Antibacterial capacities of bifidobacteria isolated from non-active ulcerative colitis against Escherichia coli LF82 and Salmonella enterica ATCC 14028 were observed more often compared to strains isolated from active ulcerative colitis. Finally, B. longum were retained as strains with the highest probiotic potential as they were the major strains presenting exopolysaccharide synthesis, antibacterial activity, and anti-inflammatory capacities. Antimicrobial activity and EPS synthesis were further correlated to the presence of antimicrobial and EPS gene clusters by in silico analysis.ConclusionsDifferent bifidobacterial taxonomic profiles were identified in the microbiota of IBD patients. The most abundant species were B. dentium, mainly associated to the microbiota of ulcerative colitis patients and B. adolescentis, in the intestinal microbiota of Crohn’s disease patients. Additionally, the relative abundance of B. dentium significantly increased with age. Furthermore, this study evidenced that bifidobacteria with probiotic potential (antipathogenic activity, exopolysaccharide production and anti-inflammatory activity), especially B. longum strains, can be isolated from the intestinal microbiota of both active and non-active Crohn’s disease and ulcerative colitis patients.

A human milk oligosaccharide prevents intestinal inflammation in adulthood via modulating gut microbial metabolism.

Observational evidence suggests that human milk oligosaccharides (HMOs) promote the growth of commensal bacteria in early life and adulthood. However, the mechanisms by which HMOs benefit health through modulation of gut microbial homeostasis remain largely unknown. 2'-fucosyllactose (2'-FL) is the most abundant oligosaccharide in human milk and contributes to the essential health benefits associated with human milk consumption. Here, we investigated how 2'-FL prevents colitis in adulthood through its effects on the gut microbial community. We found that the gut microbiota from adult mice that consumed 2'-FL exhibited an increase in abundance of several health-associated genera, including Bifidobacterium and Lactobacillus. The 2'-FL-modulated gut microbial community exerted preventive effects on colitis in adult mice. By using Bifidobacterium infantis as a 2'-FL-consuming bacterial model, exploratory metabolomics revealed novel 2'-FL-enriched secretory metabolites by Bifidobacterium infantis, including pantothenol. Importantly, pantothenate significantly protected the intestinal barrier against oxidative stress and mitigated colitis in adult mice. Furthermore, microbial metabolic pathway analysis identified 26 dysregulated metabolic pathways in fecal microbiota from patients with ulcerative colitis, which were significantly regulated by 2'-FL treatment in adult mice, indicating that 2'-FL has the potential to rectify dysregulated microbial metabolism in colitis. These findings support the contribution of the 2'-FL-shaped gut microbial community and bacterial metabolite production to the protection of intestinal integrity and prevention of intestinal inflammation in adulthood.IMPORTANCEAt present, neither basic research nor clinical studies have revealed the exact biological functions or mechanisms of action of individual oligosaccharides during development or in adulthood. Thus, it remains largely unknown whether human milk oligosaccharides could serve as effective therapeutics for gastrointestinal-related diseases. Results from the present study uncover 2'-FL-driven alterations in bacterial metabolism and identify novel B. infantis-secreted metabolites following the consumption of 2'-FL, including pantothenol. This work further demonstrates a previously unrecognized role of pantothenate in significantly protecting the intestinal barrier against oxidative stress and mitigating colitis in adult mice. Remarkably, 2'-FL-enhanced bacterial metabolic pathways are found to be dysregulated in the fecal microbiota of ulcerative colitis patients. These novel metabolic pathways underlying the bioactivities of 2'-FL may lay a foundation for applying individual oligosaccharides for prophylactic intervention for diseases associated with impaired intestinal homeostasis.

Gut microbiota-based discovery of Houttuyniae Herba as a novel prebiotic of Bacteroides thetaiotaomicron with anti-colitis activity

Ulcerative colitis (UC) represents an inflammatory disease characterized by fluctuations in severity, posing substantial challenges in treatment. The gut microbiota plays a pivotal role in the pathogenesis of UC. This study sought to identify drugs specifically targeting the gut microbiota to mitigate UC. We initiated a meta-analysis on gut microbiota in UC patients to identify UC-associated bacterial strains. Subsequently, we screened 164 dietary herbal medicines in vitro to identify potential prebiotics for the UC-associated bacterium, Bacteroides thetaiotaomicron. The DSS-induced colitis mouse model was utilized to evaluate the anti-colitis efficacy of the identified dietary herbal medicine. Full-length 16 S rRNA amplicon sequencing was employed to observe changes in gut microbiota following dietary herbal medicine intervention. The relative abundance of Bacteroides was notably diminished in UC patients compared to their healthy counterparts. B. thetaiotaomicron exhibited an inverse relationship with UC symptoms, indicating its potential as an anti-colitis agent. In vitro assessments revealed that H. Herba significantly bolstered the proliferation of B. thetaiotaomicron. Further experiments showed that treating DSS-induced mice with an aqueous extract of H. Herba considerably alleviated colitis indicators such as weight loss, colon shortening, disease activity score (DAI), and systemic inflammation. Microbial analysis revealed B. thetaiotaomicron as the sole bacterium substantially augmented by H. Herba in vivo. Overall H. Herba emerges as a promising prebiotic for B. thetaiotaomicron, offering significant anti-colitis benefits. Employing a gut microbiota-centric approach proves valuable in the quest for drug discovery.This study provides a new paradigm for drug discovery that targets the gut microbiota to treat UC.

Reduced abundance of butyric acid-producing bacteria in the ileal mucosa-associated microbiota of ulcerative colitis patients.

Compositional changes in the microbiota are associated with various inflammatory diseases, including ulcerative colitis (UC). Aim: This study aimed to investigate the mucosa-associated microbiota (MAM) in patients with UC and its difference related with disease activity and classification. Brush samples were collected from the terminal ileum and sigmoid colon during endoscopic procedures. The microbiota of samples was profiled using the Illumina MiSeq platform. The V3-V4 regions of the gene encoding 16S rRNA (460 bp) were amplified using PCR. Fifty UC patients and twenty healthy controls were enrolled. UC patients displayed significantly reduced α-diversity in both the ileum and sigmoid colon compared to controls. A difference in β-diversity in the unweighted analysis was observed between the two groups. The abundance of Lactobacillus and Veillonella was significantly higher and that of Butyricicoccus, Ruminococcus and Lachnospiraceae was significantly lower in the ileum of UC patients than in controls. The abundance of Odoribacter in the ileum was significantly lower in left-sided colitis and pancolitis patients than in proctitis patients and lower in patients with highly severe disease activity than with mild disease activity. The reduction in abundance of butyric acid-producing bacteria, especially Odoribacter, in ileal MAM may play an important role in the pathophysiology of UC.

Gluten Degradation by the Gut Microbiota of Ulcerative Colitis Patients.

Several studies have reported improved disease symptomatology in ulcerative colitis (UC) patients consuming a gluten free diet. This observation coupled with diversity depletion in the gut microbiota of UC patients led us to hypothesize that UC-associated enteric microbes differentially metabolize dietary gluten to produce immunogenic products that promote inflammation. Gluten concentration in stool was determined using gluten-specific ELISA, and gluten intake was assessed by food frequency questionnaire (FFQ) in UC (n = 12) and healthy controls (HC; n = 13). Gluten-metabolizing bacteria were isolated on minimal media supplemented with 1% gluten from UC and HC and identified by 16S rRNA profiling. Cell-free culture media from gluten metabolizing gut bacterial isolates was assessed for immunogenicity in vitro using HT29 colonocytes. Compared to HC, UC patients did not consume gluten differently (Mann-Whitney; p > 0.10) and exhibited equivalent levels of gluten in their feces (Mann-Whitney; p = 0.163). The profile of gluten-degrading bacteria isolated from UC stool was distinct (Chi-square; p ≤ 0.0001). Compared with Enterococcus isolates, products of gluten degradation by Bacillus strains induced higher IL8 and lower occludin (Mann-Whitney; p = 0.002 and p = 0.059, respectively) gene expression in colonocytes irrespective of whether they originated from UC or healthy gut. Members of HC and UC microbiota exhibit gluten-degrading ability, metabolites of which influence genes involved in inflammation and barrier function in enteric colonocyte cultures. Preliminary findings of this study warrant further investigations into the mechanisms by which gut microbiota contribute to UC pathogenesis through gluten degradation.

Composition and diverse differences of intestinal microbiota in ulcerative colitis patients

ObjectiveTo explore the composition of the intestinal microbiota in ulcerative colitis (UC) patients and to identify differences in the microbiota between patients with active disease and those in remission.MethodsBetween September 2020 and June 2021, we enrolled into our study, and collected stool samples from, patients with active UC or in remission and healthy control subjects. The diagnosis of UC was based on clinical, endoscopic, radiological, and histological findings. The composition of the intestinal microbiota was determined by sequencing of the 16S rRNA V3–V4 region and by bioinformatic methods. The functional composition of the intestinal microbiota was predicted using PICRUSt 2 (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) software.ResultsWe found that the intestinal flora was significantly less rich and diverse in UC patients than in healthy control subjects. Beta diversity analysis revealed notable differences in the intestinal flora compositions among the three groups, but there was no statistical difference in alpha diversity between UC patients with active disease and those in remission. At the phylum level, the relative abundances of Proteobacteria and Patescibacteria were significantly higher, and the relative abundances of Desulfobacterota and Verrucomicrobiota were lower, in UC patients with active disease than in the healthy control group. Higher levels of potential pathogens and lower levels of butyrate-producing bacteria were also detected in UC patients with active disease. Linear discriminant analysis Effect Size (LefSe) revealed that 71 bacterial taxa could serve as biomarkers, with 26 biomarkers at the genus level. In addition, network analysis showed that there was a positive correlation between Roseburia and Lachnospira. Functional predictions indicated that gene functions involving the metabolism of some substances, such as methane, lipopolysaccharide, geraniol, and ansamycins, were significantly different among the three groups.ConclusionThe richness and diversity of the intestinal microbiota differed significantly among the three groups. Richness describes the state of being rich in number of intestinal bacteria, whereas diversity is the number of different species of intestinal bacteria. Different bacterial taxa could be used as biomarkers, expanding our understanding of the relationship between the intestinal microbiota microenvironment and UC in the future.

Altered profiles of fecal bile acids correlate with gut microbiota and inflammatory responses in patients with ulcerative colitis.

BACKGROUNDGut microbiota and its metabolites may be involved in the pathogenesis of inflammatory bowel disease. Several clinical studies have recently shown that patients with ulcerative colitis (UC) have altered profiles of fecal bile acids (BAs). It was observed that BA receptors Takeda G-protein-coupled receptor 5 (TGR5) and vitamin D receptor (VDR) participate in intestinal inflammatory responses by regulating NF-ĸB signaling. We hypothesized that altered profiles of fecal BAs might be correlated with gut microbiota and inflammatory responses in patients with UC.AIMTo investigate the changes in fecal BAs and analyze the relationship of BAs with gut microbiota and inflammation in patients with UC.METHODSThe present study used 16S rDNA sequencing technology to detect the differences in the intestinal flora between UC patients and healthy controls (HCs). Fecal BAs were measured by targeted metabolomics approaches. Mucosal TGR5 and VDR expression was analyzed using immunohistochemistry, and serum inflammatory cytokine levels were detected by ELISA.RESULTSThirty-two UC patients and twenty-three HCs were enrolled in this study. It was found that the diversity of gut microbiota in UC patients was reduced compared with that in HCs. Firmicutes, Clostridium IV, Butyricicoccus, Clostridium XlVa, Faecalibacterium, and Roseburia were significantly decreased in patients with UC (P = 3.75E-05, P = 8.28E-07, P = 0.0002, P = 0.003, P = 0.0003, and P = 0.0004, respectively). Proteobacteria, Escherichia, Enterococcus, Klebsiella, and Streptococcus were significantly enriched in the UC group (P = 2.99E-09, P = 3.63E-05, P = 8.59E-05, P = 0.003, and P = 0.016, respectively). The concentrations of fecal secondary BAs, such as lithocholic acid, deoxycholic acid, glycodeoxycholic acid, glycolithocholic acid, and taurolithocholate, in UC patients were significantly lower than those in HCs (P = 8.1E-08, P = 1.2E-07, P = 3.5E-04, P = 1.9E-03, and P = 1.8E-02, respectively) and were positively correlated with Butyricicoccus, Roseburia, Clostridium IV, Faecalibacterium, and Clostridium XlVb (P < 0.01). The concentrations of primary BAs, such as taurocholic acid, cholic acid, taurochenodeoxycholate, and glycochenodeoxycholate, in UC patients were significantly higher than those in HCs (P = 5.3E-03, P = 4E-02, P = 0.042, and P = 0.045, respectively) and were positively related to Enterococcus, Klebsiella, Streptococcus, Lactobacillus, and pro-inflammatory cytokines (P < 0.01). The expression of TGR5 was significantly elevated in UC patients (0.019 ± 0.013 vs 0.006 ± 0.003, P = 0.0003). VDR expression in colonic mucosal specimens was significantly decreased in UC patients (0.011 ± 0.007 vs 0.016 ± 0.004, P = 0.033).CONCLUSIONFecal BA profiles are closely related to the gut microbiota and serum inflammatory cytokines. Dysregulation of the gut microbiota and altered constitution of fecal BAs may participate in regulating inflammatory responses via the BA receptors TGR5 and VDR.

Features of the gut microbiota in ulcerative colitis patients with depression: A pilot study.

Despite the establishment of the links between ulcerative colitis (UC) and depression, between UC and gut microbiota, few correlations between depression and gut microbiota have yet been demonstrated especially in ulcerative colitis patients. The objective of our study was therefore to determine whether the comorbidity of depressive disorder in ulcerative colitis patients correlate with alterations in the gut microbiota and to identify the specific microbiota signatures associated with depression.Between March 2017 and February 2018, 31 healthy volunteers, 31 UC patients without depression, and 31 UC patients with depression from Longhua Hospital were enrolled. Clinical data and fecal samples were collected for each patient. Fecal bacteria were identified using 16 s rRNA sequencing. We compared microbial composition among the 3 groups using bioinformatic analysis.Patients with UC with depression had higher disease severity (P < .05). The UC without depression group had moderate reduction of microbial abundance and uniformity compared to the control group. The UC with depression group had the lowest microbial abundance. With regard to the vital bacteria in the microbiota-gut-brain axis, patients with UC and depression had the lowest abundance of Firmicutes, Clostridia, and Clostridiales but the highest abundance of Proteobacteria, Gammaproteobacteria, and Bacilli.The presence of depression in UC patients presented significant differences in the composition of gut microbiota compared with UC patients without depression, with increased abundance of Firmicutes and reduced abundance of Proteobacteria.

Alteration of Fungal Microbiota After 5-ASA Treatment in UC Patients.

The effect of treatment regimens on fungal microbiota is unclear in ulcerative colitis (UC) patients. Here, we aimed to clarify the effect of 5-aminosalicylic acid (5-ASA) treatment on gut fungal microbiota in UC patients. Fifty-seven UC patients, including 20 treatment-naïve and 37 5-ASA-treated, were recruited into an exploration study. We compared the gut fungal profiles of these 2 groups of patients using ITS1-2 rDNA sequencing. Ten out of 20 treatment-naïve UC patients were followed up and enrolled for a validation study and underwent a 5-ASA treatment. We assessed the longitudinal differences of fungal microbiota in these patients before and after 5-ASA treatment. Results acquired from the validation study were accordant to those from the exploration study. Ascomycota was the dominant phylum in both noninflamed and inflamed mucosae. At the phylum level, Ascomycota decreased in inflamed mucosae before 5-ASA treatment. At the genus level, pathogens such as Scytalidium, Morchella, and Paecilomyces increased, and Humicola and Wickerhamomyces decreased in inflamed mucosae. After 5-ASA treatment, Ascomycota and Wickerhamomyces increased and Scytalidium, Fusarium, Morchella, and Paecilomyces decreased in both noninflamed and inflamed mucosae. Additionally, the balanced bacteria-fungi correlation was interrupted in inflamed mucosae, and 5-ASA treatment altered group-specific fungal microbiota and restored bacteria-fungi correlation in UC patients. Our results demonstrated that fungal diversity and composition were altered and the bacteria-fungi correlation was restored in inflamed mucosae after 5-ASA treatment.

Clinical Relevance of Sequencing Faecal Microbiota in Ulcerative Colitis Patients, Consanguineous and Non-Consanguineous Relatives

Clinical Relevance of Sequencing Faecal Microbiota in Ulcerative Colitis Patients, Consanguineous and Non-Consanguineous Relatives

The prevalence and transcriptional activity of the mucosal microbiota of ulcerative colitis patients

Active microbes likely have larger impact on gut health status compared to inactive or dormant microbes. We investigate the composition of active and total mucosal microbiota of treatment-naïve ulcerative colitis (UC) patients to determine the microbial picture at the start-up phase of disease, using both a 16S rRNA transcript and gene amplicon sequencing. DNA and RNA were isolated from the same mucosal colonic biopsies. Our aim was to identify active microbial members of the microbiota in early stages of disease and reveal which members are present, but do not act as major players. We demonstrated differences in active and total microbiota of UC patients when comparing inflamed to non-inflamed tissue. Several taxa, among them the Proteobacteria phyla and families therein, revealed lower transcriptional activity despite a high presence. The Bifidobacteriaceae family of the Actinobacteria phylum showed lower abundance in the active microbiota, although no difference in presence was detected. The most abundant microbiota members of the inflamed tissue in UC patients were not the most active. Knowledge of active members of microbiota in UC patients could enhance our understanding of disease etiology. The active microbial community composition did not deviate from the total when comparing UC patients to non-IBD controls.

Characterization of Intestinal Microbiota in Ulcerative Colitis Patients with and without Primary Sclerosing Cholangitis.

There is an unexplained association between ulcerative colitis [UC] and primary sclerosing cholangitis [PSC], with the intestinal microbiota implicated as an important factor. The study aim was to compare the structure of the intestinal microbiota of patients with UC with and without PSC. UC patients with PSC [PSC-UC] and without PSC [UC] were identified from biobanks at Oslo University Hospital, Foothills Hospital Calgary and Mount Sinai Hospital Toronto. Microbial DNA was extracted from colonic tissue and sequencing performed of the V4 region of the 16S rRNA gene on Illumina MiSeq. Sequences were assigned to operational taxonomic units [OTUs] using Quantitative Insights Into Microbial Ecology [QIIME]. Microbial alpha diversity, beta diversity, and relative abundance were compared between PSC-UC and UC phenotypes. In all, 31 PSC-UC patients and 56 UC patients were included. Principal coordinate analysis [PCoA] demonstrated that city of sample collection was the strongest determinant of taxonomic profile. In the Oslo cohort, Chao 1 index was modestly decreased in PSC-UC compared with UC [p = 0.04] but did not differ significantly in the Calgary cohort. No clustering by PSC phenotype was observed using beta diversity measures. For multiple microbial genera there were nominally significant differences between UC and PSC-UC, but results were not robust to false-discovery rate correction. No strong PSC-specific microbial associations in UC patients consistent across different cohorts were identified. Recruitment centre had a strong effect on microbial composition. Future studies should include larger cohorts to increase power and the ability to control for confounding factors.

P568. Alterations of Intestinal Microbiota in Ulcerative Colitis Patients Treated with Sequential Antibiotic Combination and Faecal Microbiota Transplantation

P568. Alterations of Intestinal Microbiota in Ulcerative Colitis Patients Treated with Sequential Antibiotic Combination and Faecal Microbiota Transplantation

Determination of the discriminant score of intestinal microbiota as a biomarker of disease activity in patients with ulcerative colitis

BackgroundIn recent years, the gut microbiota has been found to provide an important link to the development of inflammatory bowel diseases (IBD) like ulcerative colitis (UC). Accordingly, inter-individual variation in the gut microbial community may be linked to inter-individual variation in the risk of IBD or other diseases. Further, the Terminal Restriction Fragment Length Polymorphism (T-RFLP) is a molecular biology technique for profiling bacterial species in faecal samples. This study was to evaluate a biomarker based on intestinal microbiota.MethodsThe study subjects were 69 patients with UC together with 80 relatives as controls. Twenty-three patients had active UC (group I) and 46 had quiescent UC (group II). The later included 17 patients with mild inflammation in the large intestine (group IIa), 29 without inflammation (group IIb). The patients’ relatives were consanguineous (group III, n = 47), and non-consanguineous (group IV, n = 33). Faecal samples were obtained from all subjects for the investigation of intestinal microbiota by applying the T-RFLP method. The Discriminant analysis of operational-taxonomic-unit (OTU) on T-RFLP fingerprints was performed. The Canonical Discriminant Function Coefficient (Df) for each OTU was calculated. The individual OTUs were multiplied by the Df value, and the sum was termed the Discriminant Score (Ds).ResultsThe Ds decreased thus: group I > group IIa > group IIb > group III > group IV. Significant difference was calculated for group I vs group IV (P < 0.01), group I vs group IIb (P < 0.05), group I vs group III (P < 0.01), group IIa vs IV (P < 0.01), group IIb vs group IV (P < 0.01), group III vs group IV (P < 0.01), indicating a strong association between gut microbial species and the development of UC.ConclusionsIn this study, the Ds related to UC, or otherwise absence of UC in the five groups. Potentially, Ds may become a clinically relevant biomarker of disease activity in UC. To our knowledge, this is the first application of the Ds to the study of microbiota in UC patients, consanguineous and non-consanguineous relatives.Trial registrationClinical trial No: UMIN 000004123.

Gram-negative bacteria account for main differences between faecal microbiota from patients with ulcerative colitis and healthy controls

Detailed knowledge about the composition of the intestinal microbiota may be critical to unravel the pathogenesis of ulcerative colitis (UC), a human chronic inflammatory bowel disease, since the intestinal microbes are expected to influence some of the key mechanisms involved in the inflammatory process of the gut mucosa. The aim of this study was to investigate the faecal microbiota in patients either with UC in remission (n=6) or with active disease (n=6), and in healthy controls (n=6). The composition of Gram-negative bacteria and Gram-positive bacteria was examined. Antigenic structures of Gram-negative bacteria such as lipopolysaccharides have been related to the inflammatory responses and pathogenesis of inflammatory bowel disease. Dice cluster analysis and principal component analysis of faecal microbiota profiles obtained by denaturing gradient gel electrophoresis and quantitative PCR, respectively, revealed that the composition of faecal bacteria from UC patients with active disease differed from the healthy controls and that this difference should be ascribed to Gram-negative bacteria. The analysis did not show any clear grouping of UC patients in remission. Even with the relatively low number of subjects in each group, we were able to detect a statistically significant underrepresentation of Lactobacillus spp. and Akkermansia muciniphila in UC patients with clinically active disease compared to the healthy controls. In line with previous communications, we have shown that the microbiota in UC patients with active disease differ from that in healthy controls. Our findings indicate that alterations in the composition of the Gram-negative bacterial population, as well as reduced numbers of lactobacilli and A. muciniphila may play a role in UC.