title: The relationship between faecal-associated and mucosal-associated microbiota in irritable bowel syndrome patients and healthy subjects.
abstract: BACKGROUND
  The faecal-associated microbiota is commonly seen as a surrogate of the mucosal-associated microbiota. However, previous studies indicate that they are different. Furthermore, analyses of the mucosal microbiota are commonly done after standard bowel cleansing, affecting the microbial composition.
  
  
  OBJECTIVE
  To compare the mucosal-associated microbiota, obtained from unprepared colon, with faecal-associated microbiota in healthy subjects and irritable bowel syndrome (IBS) patients.
  
  
  METHODS
  Faecal and mucosal biopsies were obtained from 33 IBS patients and 16 healthy controls. Of IBS patients, 49% belonged to the diarrhoea-predominant subgroup and 80% suffered from IBS symptoms during at least 5 years. Biopsies were collected from unprepared sigmoid colon and faecal samples a day before colonoscopy. Microbiota analyses were performed with a phylogenetic microarray and redundancy discriminant analysis.
  
  
  RESULTS
  The composition of the mucosal- and the faecal-associated microbiota in unprepared sigmoid colon differs significantly (P = 0.002). Clinical characteristics of IBS did not correlate with this difference. Bacteroidetes dominate the mucosal-associated microbiota. Firmicutes, Actinobacteria and Proteobacteria dominate the faecal-associated microbiota. Healthy subjects had a significantly higher (P < 0.005) abundance (1.9%) of the bacterial group uncultured Clostridiales I in the mucosal-associated microbiota than IBS patients (0.3%). Bacterial diversity was higher in faecal- compared with mucosal-associated microbiota in IBS patients (P < 0.005). No differences were found in healthy subjects.
  
  
  CONCLUSIONS
  Differences in the mucosal-associated microbiota between healthy individuals and IBS patients are minimal (one bacterial group) compared to differences in the faecal microbiota of both groups (53 bacterial groups). Microbial aberrations characterising IBS are more pronounced in the faeces than in the mucosa.
authors.affiliation: School of Health and Medical Sciences, Örebro University, Örebro, Sweden.
authors.forename: I
authors.initials: I
authors.lastname: Rangel
authors.affiliation: School of Health and Medical Sciences, Örebro University, Örebro, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Sundin
authors.affiliation: Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Fuentes
authors.affiliation: School of Health and Medical Sciences, Örebro University, Örebro, Sweden.
authors.forename: D
authors.initials: D
authors.lastname: Repsilber
authors.affiliation: Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands.|Departments of Bacteriology & Immunology and Veterinary Biosciences, University of Helsinki, Helsinki, Finland.
authors.forename: W M
authors.initials: WM
authors.lastname: de Vos
authors.affiliation: School of Health and Medical Sciences, Örebro University, Örebro, Sweden.
authors.forename: R J
authors.initials: RJ
authors.lastname: Brummer
mesh_terms: D000328:Adult; D001706:Biopsy; D003113:Colonoscopy; D003967:Diarrhea / Q000382:microbiology*; D005243:Feces / Q000382:microbiology*; D005260:Female; D006801:Humans; D007422:Intestines / Q000382:microbiology; D043183:Irritable Bowel Syndrome / Q000175:diagnosis / Q000382:microbiology*; D008297:Male; D064307:Microbiota; D008875:Middle Aged; D009092:Mucous Membrane / Q000382:microbiology; D010802:Phylogeny; D055815:Young Adult