title: Changes in the Abundance of Faecalibacterium prausnitzii Phylogroups I and II in the Intestinal Mucosa of Inflammatory Bowel Disease and Patients with Colorectal Cancer.
abstract: BACKGROUND
  Faecalibacterium prausnitzii comprises 2 phylogroups, whose abundance in healthy and diseased gut and in conjunction with Escherichia coli has not yet been studied. This work aims to determine the contribution of F. prausnitzii phylogroups I and II in intestinal disease and to assess their potential diagnostic usefulness as biomarkers for gut diseases.
  
  
  METHODS
  Total F. prausnitzii, its phylogroups, and E. coli loads were determined by quantitative polymerase chain reaction targeting the 16S rRNA gene on biopsies from 31 healthy controls (H), 45 patients with Crohn's disease (CD), 25 patients with ulcerative colitis, 10 patients with irritable bowel syndrome, and 20 patients with colorectal cancer. Data were normalized to total bacterial counts and analyzed according to patients' disease location and clinical characteristics.
  
  
  RESULTS
  Lower levels of both total F. prausnitzii and phylogroup I were found in subjects with CD, ulcerative colitis, and colorectal cancer (P < 0.001) compared with H subjects. Phylogroup I load was a better biomarker than total F. prausnitzii to discriminate subjects with gut disorders from H. Phylogroup II depletion was observed only in patients with CD (P < 0.001) and can be potentially applied to differentiate ulcerative pancolitis from colonic CD. No statistically significant correlation between E. coli and any of the 2 F. prausnitzii phylogroups was found in any group of patients or by inflammatory bowel disease location. Phylogroup I was lower in active patients with CD, whereas those CD with intestinal resection showed a reduction in phylogroup II. Treatments with mesalazine and immunosuppressants did not result in the recovery of F. prausnitzii phylogroups abundance.
  
  
  CONCLUSIONS
  F. prausnitzii phylogroup I was depleted in CD, ulcerative colitis, and colorectal cancer, whereas phylogroup II was specifically reduced in CD. Quantification of F. prausnitzii phylogroups and E. coli may help to identify gut disorders and to classify inflammatory bowel disease location.
authors.affiliation: *Department of Biology, Laboratory of Molecular Microbiology, Universitat de Girona, Girona, Spain; †Department of Gastroenterology, Hospital Dr. Josep Trueta, Girona, Spain; ‡Department of Gastroenterology, Hospital Santa Caterina, Salt, Girona, Spain; and §Gut Health Unit, Microbial Ecology Group, Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, United Kingdom.
authors.forename: Mireia
authors.initials: M
authors.lastname: Lopez-Siles
authors.forename: Margarita
authors.initials: M
authors.lastname: Martinez-Medina
authors.forename: Romà
authors.initials: R
authors.lastname: Surís-Valls
authors.forename: Xavier
authors.initials: X
authors.lastname: Aldeguer
authors.forename: Miriam
authors.initials: M
authors.lastname: Sabat-Mir
authors.forename: Sylvia H
authors.initials: SH
authors.lastname: Duncan
authors.forename: Harry J
authors.initials: HJ
authors.lastname: Flint
authors.forename: L Jesús
authors.initials: LJ
authors.lastname: Garcia-Gil
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D005260:Female; D005500:Follow-Up Studies; D006094:Gram-Positive Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D016908:Gram-Positive Bacterial Infections / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics / Q000382:microbiology*; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics / Q000382:microbiology*; D007413:Intestinal Mucosa / Q000382:microbiology*; D008297:Male; D008875:Middle Aged; D010802:Phylogeny; D015995:Prevalence; D011379:Prognosis; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S