Functional 13C-urea and glucose hydrogen/methane breath tests reveal significant association of small intestinal bacterial overgrowth in individuals with active Helicobacter pylori infection

Clin Biochem. 2017 Jan;50(1-2):46-49. doi: 10.1016/j.clinbiochem.2016.08.017. Epub 2016 Aug 30.


Objectives: Helicobacter pylori infection is considered to alter the bacterial flora in the upper gastrointestinal tract. This study aimed at investigating the presence of small intestinal bacterial overgrowth (SIBO) in patients with active H. pylori infection assessed by functional breath testing.

Design and methods: A total of 109 outpatients, who were referred for the H. pylori13C-urea breath test (13C-UBT) by general practitioners and specialists, were also tested for the presence of SIBO by the glucose hydrogen (H2)/methane (CH4) breath test (HMBT). A detailed anamnesis was carried out about the history of H. pylori infection, eradication therapies, proton pump inhibitor intake, and comorbidities.

Results: In total, 36/109 (33.0%) patients had a positive H. pylori13C-UBT, and 35/109 (32.1%) patients had a positive glucose HMBT, the latter being indicative of SIBO. Interestingly, individuals with a positive H. pylori13C-UBT were significantly more often associated with a positive glucose HMBT (p=0.002). Cohen's κ measuring agreement between the 13C-UBT and the glucose HMBT was 0.31 (confidence intervals: 0.12-0.50) (p=0.001). Altogether, 19 of 54 (35.2%) patients, who had completed up to four eradication therapies, were diagnosed with SIBO by HMBT.

Conclusions: H. pylori infection was found to be significantly associated with the presence of SIBO as determined by functional breath testing. In addition, SIBO rates appeared to have increased after completed eradication therapies. However, further longitudinal studies are warranted to fully elucidate the relationship and treatment modalities of coincident H. pylori infection and SIBO.

Keywords: Functional breath testing; Helicobacter pylori infection; Small intestinal bacterial overgrowth.

MeSH terms

  • Adult
  • Breath Tests
  • Female
  • Glucose / metabolism*
  • Helicobacter Infections / microbiology*
  • Helicobacter pylori / growth & development*
  • Humans
  • Intestine, Small / microbiology*
  • Male
  • Methane / metabolism*
  • Middle Aged
  • Urea / metabolism*


  • Urea
  • Glucose
  • Methane