- Small intestinal bacterial overgrowth (SIBO) and methane overgrowth may be separate entities, according to guidelines published by the American College of Gastroenterology.
- SIBO remains poorly understood.
Why this matters
- SIBO has been linked to a host of diseases.
- Reversible sequelae include malabsorption, micronutrient deficiencies.
- Treatment remains nonstandardized.
- Issued with Practice Parameters Committee of the American College of Gastroenterology.
- Includes suggestions for trial design.
- Defined as either:
- Duodenal/jejunal aspirate finding ≥103 colony-forming units/mL; or
- Breath test: after oral intake of glucose (75 g) or lactulose (10 g), subsequent rise in exhaled hydrogen of ≥20 parts per million above baseline within 90 minutes.
- When considering diagnosis, weigh risk factors, including previous treatments of other conditions.
- Authors recommend breath testing for patients with irritable bowel syndrome, suspected symptomatic motility disorders, or previous luminal abdominal surgery, but not for asymptomatic patients taking proton-pump inhibitors.
- Use glucose hydrogen or lactulose hydrogen.
- Sensitivity, specificity are low.
- If excessive methane on breath, authors propose new entity, intestinal methanogen overgrowth, recognizing archaea overgrowth.
- They recommend assessing methane via breath tests for symptomatic patients with constipation.
- As treatment, authors suggest antibiotics (e.g., rifaximin), ideally after objective diagnosis.
- Evidence is scarce regarding low-FODMAP diet, probiotics, intestinal microbiota transplant.
- All recommendations are conditional, with very low level of evidence.