title: Alterations in the colonic microbiota in response to osmotic diarrhea.
abstract: OBJECTIVE
  Diseases of the human gastrointestinal (GI) tract are often accompanied by diarrhea with profound alterations in the GI microbiota termed dysbiosis. Whether dysbiosis is due to the disease itself or to the accompanying diarrhea remains elusive. With this study we characterized the net effects of osmotic diarrhea on the composition of the GI microbiota in the absence of disease.
  
  
  METHODS
  We induced osmotic diarrhea in four healthy adults by oral administration of polyethylene glycol 4000 (PEG). Stool as well as mucosa specimens were collected before, during and after diarrhea and 16S rDNA-based microbial community profiling was used to assess the microbial community structure.
  
  
  RESULTS
  Stool and mucosal microbiotas were strikingly different, with Firmicutes dominating the mucosa and Bacteroidetes the stools. Osmotic diarrhea decreased phylotype richness and showed a strong tendency to equalize the otherwise individualized microbiotas on the mucosa. Moreover, diarrhea led to significant relative shifts in the phyla Bacteroidetes and Firmicutes and to a relative increase in the abundance of Proteobacteria on the mucosa, a phenomenon also noted in several inflammatory and diarrheal GI diseases.
  
  
  CONCLUSIONS
  Changes in microbial community structure induced by osmotic diarrhea are profound and show similarities to changes observed in other GI diseases including IBD. These effects so must be considered when specimens from diarrheal diseases (i.e. obtained by stratification of samples according to diarrheal status) or conditions wherein bowel preparations like PEG (i.e. specimens obtained during endoscopy) are used.
authors: Institute of Pathology, Medical University of Graz, Graz, Austria. gregor.gorkiewicz@medunigraz.at
authors: Gregor
authors: G
authors: Gorkiewicz
authors: Gerhard G
authors: GG
authors: Thallinger
authors: Slave
authors: S
authors: Trajanoski
authors: Stefan
authors: S
authors: Lackner
authors: Gernot
authors: G
authors: Stocker
authors: Thomas
authors: T
authors: Hinterleitner
authors: Christian
authors: C
authors: Gülly
authors: Christoph
authors: C
authors: Högenauer
mesh_terms: D000328:Adult; D003106:Colon / Q000382:microbiology*; D003967:Diarrhea / Q000139:chemically induced / Q000382:microbiology*; D005243:Feces / Q000382:microbiology; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects / Q000382:microbiology; D008297:Male; D054892:Metagenome / Q000235:genetics; D008875:Middle Aged; D009995:Osmosis / Q000187:drug effects; D011092:Polyethylene Glycols / Q000009:adverse effects
chemical_list: D011092:Polyethylene Glycols