Risk factors for small bowel bacterial overgrowth in cystic fibrosis

J Pediatr Gastroenterol Nutr. 2007 Feb;44(2):212-8. doi: 10.1097/MPG.0b013e31802c0ceb.


Objectives: The purpose of this study was to determine the prevalence of small bowel bacterial overgrowth in patients with pancreatic-insufficient cystic fibrosis (CF) compared with age-matched controls and to identify potential risk factors for small bowel bacterial overgrowth.

Patients and methods: Fifty patients, 25 pancreatic-insufficient CF study patients (mean age, 17 y) and 25 gastrointestinal clinic control patients (mean age, 15 y), completed a glucose-hydrogen breath test after an overnight fast. Study patients completed a quality-of-life questionnaire modified from the Cystic Fibrosis Questionnaire. The medical history of each patient was compared with breath test results. A positive breath test was defined as a fasting hydrogen > or =15 ppm or a rise of > or =10 ppm hydrogen over baseline during the test.

Results: The prevalence of positive breath tests was higher in the CF study group (56%) than in the control group (20%) (P = 0.02). The mean fasting hydrogen levels of patients in the study and control groups were 22 and 5 ppm (P = 0.0001). The mean questionnaire scores were not significantly different between breath test-positive and -negative study patients. The use of azithromycin was associated with an increased risk of a positive breath test. Use of laxatives and inhaled ipratropium was associated with a decreased risk of a positive breath test.

Conclusions: Patients with CF were more likely to have elevated fasting hydrogen levels compared with controls. This suggests a high prevalence of small bowel bacterial overgrowth in CF patients. Medications commonly used by CF patients may influence intestinal health.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Bacterial Infections / diagnosis
  • Bacterial Infections / microbiology*
  • Breath Tests
  • Child
  • Child, Preschool
  • Cystic Fibrosis / complications*
  • Female
  • Humans
  • Hydrogen / analysis
  • Intestinal Diseases / diagnosis
  • Intestinal Diseases / microbiology*
  • Intestine, Small / microbiology*
  • Male
  • Middle Aged
  • Prevalence
  • Quality of Life
  • Risk Factors


  • Hydrogen