title: Unstable composition of the fecal microbiota in ulcerative colitis during clinical remission.
abstract: OBJECTIVE
  Studies have identified abnormal characteristics of the gut microbiota in patients with active IBD, but whether the changes are causal or secondary to inflammation remains uncertain. We investigated dynamics of fecal microbiota in ulcerative colitis (UC) during remission by genomic technology.
  
  
  METHODS
  Patients in clinical remission and on stable maintenance mesalazine therapy were recruited (N = 33). Fecal samples were collected at regular intervals over a period of 1 yr. Sixteen patients who remained in remission and eight healthy controls were included in the analysis. Variable V6 to V8 regions of the 16S rRNA gene in DNA extracts from fecal samples were amplified by polymerase chain reaction. Amplicons were separated by denaturant gradient gel electrophoresis, band profiles were compared by software, and similarity indices were calculated from densitometric curves.
  
  
  RESULTS
  Band profiles showed unique patterns with low similarity index between individuals, suggesting host specificity in the predominant microbiota. Within the same individual, profiles were stable in controls but varied notably over time in patients. In controls, the similarity index was remarkably stable (78 +/- 8% mean +/- SD) over a period of 24 months. However, patients showed a steady decline in similarity index versus the initial profile, dropping down to 42 +/- 24% at month 3 of follow-up and to 23 +/- 19% at month 12 (P < 0.001). Biodiversity of the dominant microbiota, as estimated by number of bands, was lower in patients (17 +/- 4) than controls (23 +/- 4, P < 0.01).
  
  
  CONCLUSIONS
  Molecular analysis of fecal bacteria in patients with inactive UC shows low biodiversity and temporal instability.
authors.affiliation: Digestive Disease Research Unit, University Hospital Vall d'Hebron, Ciberehd, Barcelona, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Martinez
authors.forename: Maria
authors.initials: M
authors.lastname: Antolin
authors.forename: Javier
authors.initials: J
authors.lastname: Santos
authors.forename: Antonio
authors.initials: A
authors.lastname: Torrejon
authors.forename: Francesc
authors.initials: F
authors.lastname: Casellas
authors.forename: Natalia
authors.initials: N
authors.lastname: Borruel
authors.forename: Francisco
authors.initials: F
authors.lastname: Guarner
authors.forename: Juan-R
authors.initials: JR
authors.lastname: Malagelada
mesh_terms: D000328:Adult; D003093:Colitis, Ulcerative / Q000382:microbiology*; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D005243:Feces / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012074:Remission Induction
chemical_list: D004269:DNA, Bacterial