Unstable composition of the fecal microbiota in ulcerative colitis during clinical remission.
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.
Martinez
Cristina
C
Digestive Disease Research Unit, University Hospital Vall d'Hebron, Ciberehd, Barcelona, Spain.
Antolin
Maria
M
Santos
Javier
J
Torrejon
Antonio
A
Casellas
Francesc
F
Borruel
Natalia
N
Guarner
Francisco
F
Malagelada
Juan-R
JR
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
D004269:DNA, Bacterial