Small-Intestinal Bacterial Overgrowth is Associated With Concurrent Intestinal Inflammation But Not With Systemic Inflammation in Crohn's Disease Patients

J Clin Gastroenterol. 2018 Jul;52(6):530-536. doi: 10.1097/MCG.0000000000000803.


Goals: We studied the prevalence and predictors of small-intestinal bacterial overgrowth (SIBO) in Crohn's disease (CD) outpatients and the relationship between SIBO and intestinal and/or systemic inflammation.

Background: The relationship of SIBO with systemic and intestinal inflammation in CD patients is unclear.

Study: In this cross-sectional study, conducted between June, 2013 and January, 2015, 92 CD patients and 97 controls with nonchronic gastrointestinal complaints were assessed for the presence of SIBO using the H2/CH4 glucose breath test. Multivariate logistic regression was performed to investigate the potential association between SIBO and demographic, disease-related data, systemic markers of inflammation (C-reactive protein, and erythrocyte sedimentation rate), and biomarker of intestinal inflammation [fecal calprotectin concentration (FCC)].

Results: The SIBO rate was significantly higher in CD patients than in controls (32.6% vs. 12.4%, respectively, P=0.0008). Patients with and without SIBO were comparable with regard to demographics, systemic inflammatory biomarkers, and disease characteristics, except for the stricturing phenotype being more common in SIBO-positive CD patients (43.3% vs. 19.3%, P=0.015). Notably, FCC was significantly higher in SIBO-positive patients (median of 485.8 vs.132.7 μg/g; P=0.004). Patients presenting increased FCC and stricturing disease had an odds of 9.43 (95% confidence interval, 3.04-11.31; P<0.0001) and 3.83 (95% confidence interval, 1.54-6.75; P=0.025) respectively, for SIBO diagnosis.

Conclusions: In CD patients, SIBO is a highly prevalent condition. Stricturing phenotype and increased FCC were strongly and independently associated with the presence of SIBO. SIBO diagnostic work-up followed by directed treatment is recommended in CD patients who present stricturing disease, especially in those with concurrent intestinal inflammation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Biomarkers / blood
  • Blind Loop Syndrome / blood
  • Blind Loop Syndrome / diagnosis
  • Blind Loop Syndrome / epidemiology*
  • Blind Loop Syndrome / microbiology
  • Blood Sedimentation
  • Brazil / epidemiology
  • C-Reactive Protein / analysis
  • Case-Control Studies
  • Crohn Disease / blood*
  • Crohn Disease / diagnosis
  • Crohn Disease / epidemiology*
  • Crohn Disease / microbiology
  • Cross-Sectional Studies
  • Feces / chemistry
  • Female
  • Gastrointestinal Microbiome*
  • Humans
  • Inflammation Mediators / blood
  • Intestine, Small / microbiology*
  • Leukocyte L1 Antigen Complex / analysis
  • Male
  • Middle Aged
  • Phenotype
  • Prevalence
  • Prospective Studies
  • Risk Assessment
  • Risk Factors
  • Young Adult


  • Biomarkers
  • Inflammation Mediators
  • Leukocyte L1 Antigen Complex
  • C-Reactive Protein