title: The intestinal mucus layer from patients with inflammatory bowel disease harbors high numbers of bacteria compared with controls.
abstract: OBJECTIVE
  Whether the bacterial flora contributes to the pathogenesis of inflammatory bowel disease (IBD) by increased penetration in mucus, increased adherence to epithelial cells, or invasion of the epithelium is unknown. We therefore studied the spatial distribution of bacteria in the mucosa of rectal biopsy specimens from patients with IBD and from controls.
  
  
  METHODS
  Rectal biopsy specimens from 19 patients with IBD and from 14 controls were studied by using nonradioactive ribosomal RNA in situ hybridization. Total mucosal surface length examined for each patient was measured, and the number of bacteria visualized was estimated semiquantitatively.
  
  
  RESULTS
  No bacteria were observed in biopsy specimens from 10 controls (71%) and 6 IBD patients (32%) (P = 0.04; odds ratio, 5.42; 95% confidence interval, 1.23-23.9). IBD rectal specimens contained significantly more bacteria than control samples (P = 0.004). Bacteria were localized within the mucus layer but did not adhere to the epithelial cells and were not present within the lamina propria. There was no correlation between the numbers of bacteria present and either the degree of inflammation or the use of anti-inflammatory agents or sulfasalazine compounds.
  
  
  CONCLUSIONS
  The intestinal mucus in IBD patients is less protective against the endogenous microflora than in controls, resulting in increased association of luminal bacteria with the mucus layer.
authors.affiliation: Department of Medical Microbiology, Academic Medical Centre, Amsterdam, The Netherlands. cschultsz@amc.uva.nl
authors.forename: C
authors.initials: C
authors.lastname: Schultsz
authors.forename: F M
authors.initials: FM
authors.lastname: Van Den Berg
authors.forename: F W
authors.initials: FW
authors.lastname: Ten Kate
authors.forename: G N
authors.initials: GN
authors.lastname: Tytgat
authors.forename: J
authors.initials: J
authors.lastname: Dankert
mesh_terms: D001419:Bacteria / Q000302:isolation & purification*; D001706:Biopsy; D003106:Colon / Q000382:microbiology / Q000473:pathology; D015169:Colony Count, Microbial; D006801:Humans; D007082:Ileum / Q000382:microbiology / Q000473:pathology; D017403:In Situ Hybridization; D015212:Inflammatory Bowel Diseases / Q000378:metabolism / Q000382:microbiology* / Q000473:pathology; D007413:Intestinal Mucosa / Q000378:metabolism*; D009077:Mucins / Q000378:metabolism; D009093:Mucus / Q000378:metabolism / Q000382:microbiology*; D012007:Rectum / Q000382:microbiology / Q000473:pathology; D012016:Reference Values; D013194:Staining and Labeling
chemical_list: D009077:Mucins