Abnormal microbiota composition in the ileocolonic mucosa of Crohn's disease patients as revealed by polymerase chain reaction-denaturing gradient gel electrophoresis.
BACKGROUND
Bacteria might play a role in the pathogenesis of Crohn's disease (CD), and patients harbor a different type and density of gut microbiota compared with normal healthy subjects. Thus, the aim of this study was to compare the microbiota adhered to the mucosa of CD patients with that of healthy subjects.


METHODS
Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) of 16S rRNA gene fragments was used to identify the dominant bacterial species present in fresh biopsy samples obtained from the mucosa of 15 healthy and 19 CD subjects. Two patients suffering from ulcerative colitis and 1 suffering from ischemic colitis also were included.


RESULTS
Individuals were clustered in 2 groups according to their molecular fingerprint, which differentiated the majority of CD specimens (88.2%) from the majority of healthy/ulcerative colitis/ischemic colitis specimens (82.3%). In addition, the patient-to-patient variability in microbiota was greater within the CD cluster than in the healthy/ulcerative colitis cluster (P = 0.000). One hundred forty-one sequences were obtained from the PCR-DGGE bands that were grouped into 58 different phylotypes, 8 of which were novel. BLAST analysis revealed that 74.5% of the sequences were similar to those of bacteria that have never been cultivated. In CD samples, prevalence values for Clostridium spp Ruminococcus torques and Escherichia coli were significantly higher, whereas Faecalibacterium was more frequently found in healthy specimens. Opportunistic pathogenic gamma-proteobacteria were found occasionally, only in CD mucosal microbiota.


CONCLUSIONS
Microbiota attached to the ileocolonic mucosa of CD patients is distinguishable from that of healthy subjects. We postulate that individuals who are predisposed to CD are less able to regulate the microbial makeup of their intestines, which leads to an unstable microbial population.
Martinez-Medina
Margarita
M
Laboratory of Molecular Microbiology, Department of Biology, University of Girona, E-17071 Girona, Spain.
Aldeguer
Xavier
X
Gonzalez-Huix
Ferran
F
Acero
Doroteo
D
Garcia-Gil
L Jesús
LJ
D000328:Adult; D016022:Case-Control Studies; D016000:Cluster Analysis; D003424:Crohn Disease / Q000382:microbiology*; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods*; D005260:Female; D006801:Humans; D007079:Ileitis / Q000382:microbiology*; D007413:Intestinal Mucosa / Q000382:microbiology*; D008297:Male; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods*; D012336:RNA, Ribosomal, 16S / Q000032:analysis / Q000235:genetics; D017422:Sequence Analysis, DNA
D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S