Patchy distribution of mucosal lesions in ileal Crohn's disease is not linked to differences in the dominant mucosa-associated bacteria: a study using fluorescence in situ hybridization and temporal temperature gradient gel electrophoresis.
BACKGROUND
The mucosa-associated bacteria (MAB) are suspected of being involved in the pathogenesis of Crohn's disease. We analyzed and compared the MAB in noninflamed and inflamed ileal mucosa of Crohn's disease patients (n = 22).


METHODS
Tissue samples from the inflamed ileal mucosa and from the adjacent noninflamed ileal mucosa were taken from surgical resection specimens. The MAB were investigated using fluorescence in situ hybridization with 7 group-specific probes and temporal temperature gradient gel electrophoresis (TTGE).


RESULTS
Samples from both noninflamed and inflamed mucosa were obtained from 15 patients. The distribution of the bacterial populations was not different between noninflamed and inflamed mucosa. The Bacteroidetes phylum was dominant and accounted for 29% of MAB (0%-74%) in noninflamed tissues and 32% (0%-70%) in inflamed areas. The gamma Proteobacteria represented 12% (0%-70%) of MAB both in noninflamed and inflamed areas. The Clostridium coccoides group (Firmicutes phylum) represented 15% of MAB in noninflamed tissues versus 7% in inflamed areas. For most of the patients the similarity index between TTGE paired profiles was very high.


CONCLUSIONS
The dominant MAB do not differ between noninflamed and inflamed ileal mucosa in Crohn's disease. This argues against a localized dysbiosis to explain the patchy distribution of mucosal lesions.
Vasquez
Nadia
N
Laboratoire de Biologie EA 3199, CNAM, 2 rue Conté 75003 Paris, France.
Mangin
Irène
I
Lepage
Patricia
P
Seksik
Philippe
P
Duong
Jean-Paul
JP
Blum
Stéphanie
S
Schiffrin
Eduardo
E
Suau
Antonia
A
Allez
Matthieu
M
Vernier
Gwenola
G
Tréton
Xavier
X
Doré
Joël
J
Marteau
Philippe
P
Pochart
Philippe
P
D000328:Adult; D001419:Bacteria / Q000235:genetics* / Q000302:isolation & purification*; D001706:Biopsy; D015169:Colony Count, Microbial; D003424:Crohn Disease / Q000188:drug therapy / Q000382:microbiology* / Q000473:pathology; D004269:DNA, Bacterial / Q000032:analysis*; D004311:Double-Blind Method; D004586:Electrophoresis / Q000379:methods; D005260:Female; D006801:Humans; D007082:Ileum / Q000382:microbiology* / Q000473:pathology; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D007413:Intestinal Mucosa / Q000382:microbiology* / Q000473:pathology; D007778:Lactobacillus; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D019936:Probiotics / Q000627:therapeutic use; D013696:Temperature
D004269:DNA, Bacterial