title: Distinct microbial populations exist in the mucosa-associated microbiota of sub-groups of irritable bowel syndrome.
abstract: BACKGROUND
  There is increasing evidence to support a role for the gastrointestinal microbiota in the etiology of irritable bowel syndrome (IBS). Given the evidence of an inflammatory component to IBS, the mucosa-associated microbiota potentially play a key role in its pathogenesis. The objectives were to compare the mucosa-associated microbiota between patients with diarrhea predominant IBS (IBS-D), constipation predominant IBS (IBS-C) and controls using fluorescent in situ hybridization and to correlate specific bacteria groups with individual IBS symptoms.
  
  
  METHODS
  Forty-seven patients with IBS (27 IBS-D and 20 IBS-C) and 26 healthy controls were recruited to the study. Snap-frozen rectal biopsies were taken at colonoscopy and bacterial quantification performed by hybridizing frozen sections with bacterial-group specific oligonucleotide probes.
  
  
  RESULTS
  Patients with IBS had significantly greater numbers of total mucosa-associated bacteria per mm of rectal epithelium than controls [median 218 (IQR - 209) vs 128 (121) P = 0.007], and this was chiefly comprised of bacteroides IBS [69 (67) vs 14 (41) P = 0.001] and Eubacterium rectale-Clostridium coccoides [52 (58) vs 25 (35) P = 0.03]. Analysis of IBS sub-groups demonstrated that bifidobacteria were lower in the IBS-D group than in the IBS-C group and controls [24 (32) vs 54 (88) vs 32 (35) P = 0.011]. Finally, amongst patients with IBS, the maximum number of stools per day negatively correlated with the number of mucosa-associated bifidobacteria (P < 0.001) and lactobacilli (P = 0.002).
  
  
  CONCLUSIONS
  The mucosa-associated microbiota in patients with IBS is significantly different from healthy controls with increases in bacteroides and clostridia and a reduction in bifidobacteria in patients with IBS-D.
authors: Diet and Gastrointestinal Health, Nutritional Sciences Division, King's College London, London, UK. gareth.parkes@kcl.ac.uk
authors: G C
authors: GC
authors: Parkes
authors: N B
authors: NB
authors: Rayment
authors: B N
authors: BN
authors: Hudspith
authors: L
authors: L
authors: Petrovska
authors: M C
authors: MC
authors: Lomer
authors: J
authors: J
authors: Brostoff
authors: K
authors: K
authors: Whelan
authors: J D
authors: JD
authors: Sanderson
mesh_terms: D000328:Adult; D001419:Bacteria / Q000235:genetics; D001706:Biopsy; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000382:microbiology* / Q000473:pathology; D043183:Irritable Bowel Syndrome / Q000382:microbiology* / Q000473:pathology / Q000503:physiopathology; D008297:Male; D054892:Metagenome; D012007:Rectum / Q000033:anatomy & histology / Q000382:microbiology / Q000601:surgery