title: Standard colonic lavage alters the natural state of mucosal-associated microbiota in the human colon.
abstract: OBJECTIVE
  Past studies of the human intestinal microbiota are potentially confounded by the common practice of using bowel-cleansing preparations. We examined if colonic lavage changes the natural state of enteric mucosal-adherent microbes in healthy human subjects.
  
  
  METHODS
  Twelve healthy individuals were divided into three groups; experimental group, control group one, and control group two. Subjects in the experimental group underwent an un-prepped flexible sigmoidoscopy with biopsies. Within two weeks, subjects were given a standard polyethylene glycol-based bowel cleansing preparation followed by a second flexible sigmoidoscopy. Subjects in control group one underwent two un-prepped flexible sigmoidoscopies within one week. Subjects in the second control group underwent an un-prepped flexible sigmoidoscopy followed by a second flexible sigmoidoscopy after a 24-hour clear liquid diet within one week. The mucosa-associated microbial communities from the two procedures in each subject were compared using 16S rRNA gene based terminal restriction fragment length polymorphism (T-RFLP), and library cloning and sequencing.
  
  
  RESULTS
  Clone library sequencing analysis showed that there were changes in the composition of the mucosa-associated microbiota in subjects after colonic lavage. These changes were not observed in our control groups. Standard bowel preparation altered the diversity of mucosa-associated microbiota. Taxonomic classification did not reveal significant changes at the phylum level, but there were differences observed at the genus level.
  
  
  CONCLUSIONS
  Standard bowel cleansing preparation altered the mucosal-adherent microbiota in all of our subjects, although the degree of change was variable. These findings underscore the importance of considering the confounding effects of bowel preparation when designing experiments exploring the gut microbiota.
authors.affiliation: Section of Gastroenterology, Department of Medicine, University of Chicago Medical Center, Chicago, Illinois, United States of America.
authors.forename: Laura
authors.initials: L
authors.lastname: Harrell
authors.forename: Yunwei
authors.initials: Y
authors.lastname: Wang
authors.forename: Dionysios
authors.initials: D
authors.lastname: Antonopoulos
authors.forename: Vincent
authors.initials: V
authors.lastname: Young
authors.forename: Lev
authors.initials: L
authors.lastname: Lichtenstein
authors.forename: Yong
authors.initials: Y
authors.lastname: Huang
authors.forename: Stephen
authors.initials: S
authors.lastname: Hanauer
authors.forename: Eugene
authors.initials: E
authors.lastname: Chang
mesh_terms: D000328:Adult; D003106:Colon / Q000382:microbiology*; D006801:Humans; D007413:Intestinal Mucosa / Q000382:microbiology*; D054892:Metagenome / Q000235:genetics; D008875:Middle Aged; D012150:Polymorphism, Restriction Fragment Length / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012812:Sigmoidoscopy
chemical_list: D012336:RNA, Ribosomal, 16S