Small intestinal bacterial overgrowth in patients with irritable bowel syndrome

Gut. 2007 Jun;56(6):802-8. doi: 10.1136/gut.2006.108712. Epub 2006 Dec 5.

Abstract

Background: Small intestinal bacterial overgrowth (SIBO) has been proposed to be common in irritable bowel syndrome (IBS), with altered small-bowel motility as a possible predisposing factor.

Aim: To assess the prevalence of SIBO, by culture of small-bowel aspirate, and its correlation to symptoms and motility in IBS.

Methods: 162 patients with IBS who underwent small-bowel manometry and culture of jejunal aspirate were included. Cultures from 26 healthy subjects served as controls. Two definitions of altered flora were used: the standard definition of SIBO (>/=10(5) colonic bacteria/ml), and mildly increased counts of small-bowel bacteria (>/=95th centile in controls).

Results: SIBO (as per standard definition) was found in 4% of both patients and controls. Signs of enteric dysmotility were seen in 86% of patients with SIBO and in 39% of patients without SIBO (p = 0.02). Patients with SIBO had fewer phase III activities (activity fronts) than patients without SIBO (p = 0.08), but otherwise no differences in motility parameters were seen. Mildly increased bacterial counts (>/=5x10(3)/ml) were more common in patients with IBS than in controls (43% vs 12%; p = 0.002), but this was unrelated to small intestinal motility. No correlation between bacterial alterations and symptom pattern was observed.

Conclusions: The data do not support an important role for SIBO according to commonly used clinical definitions, in IBS. However, mildly increased counts of small-bowel bacteria seem to be more common in IBS, and needs further investigation. Motility alterations could not reliably predict altered small-bowel bacterial flora.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Anti-Bacterial Agents / therapeutic use
  • Bacteria / growth & development
  • Bacteria / isolation & purification*
  • Bacterial Infections / complications
  • Bacterial Infections / drug therapy
  • Breath Tests / methods
  • Constipation / microbiology
  • Constipation / physiopathology
  • Diarrhea / microbiology
  • Diarrhea / physiopathology
  • Female
  • Gastrointestinal Motility
  • Humans
  • Intestine, Small / microbiology*
  • Intestine, Small / physiopathology
  • Irritable Bowel Syndrome / drug therapy
  • Irritable Bowel Syndrome / microbiology*
  • Irritable Bowel Syndrome / physiopathology
  • Jejunum / microbiology
  • Male
  • Manometry / methods
  • Middle Aged
  • Treatment Outcome

Substances

  • Anti-Bacterial Agents