Treatment of Small Intestinal Bacterial Overgrowth (SIBO)

Diagnostic Approach

The British Society of Gastroenterology recommends testing rather than empirical treatment to improve antibiotic stewardship and avoid treating patients who don't actually have SIBO 1
Combined hydrogen and methane breath testing is more accurate than hydrogen-only testing for identifying SIBO 1, 2
Glucose or lactulose breath tests should be used when available 1
Qualitative small bowel aspiration during upper endoscopy is an alternative when breath testing is unavailable 1

Rifaximin 550 mg twice daily for 1-2 weeks is the first-line treatment for proven SIBO, achieving 60-80% efficacy in eradicating bacterial overgrowth 1, 2
Rifaximin is preferred because it reduces systemic resistance risk 1, 2
Effective for both hydrogen-dominant and methane-dominant SIBO 1
Doxycycline, Ciprofloxacin, Amoxicillin-clavulanic acid, and Cefoxitin are equally effective alternatives 1, 2
Metronidazole should be avoided as first-line treatment due to documented lower efficacy 1, 2

For patients with recurrent SIBO, use one of the following strategies: cyclical antibiotics, low-dose long-term antibiotics, or recurrent short courses of antibiotics 1, 2
Patients with reversible causes typically need only one antibiotic course, while those with persistent underlying causes require ongoing management strategies 1

A low-FODMAP diet for 2-4 weeks reduces fermentable carbohydrates that feed bacterial overgrowth, although this citation is from a less preferred source 5
Adequate protein intake while reducing fat consumption minimizes steatorrhea, although this citation is from a less preferred source 5
Complex carbohydrates and fiber from non-cereal plant sources support gut motility, although this citation is from a less preferred source 5, 4

Monitor for nutritional deficiencies, including fat-soluble vitamins (A, D, E, K), vitamin B12, and iron 5
Vitamin D deficiency occurs in 20% of patients if bile acid sequestrants are needed 1
Consider bile salt sequestrants (cholestyramine or colesevelam) for persistent steatorrhea, starting at low doses and titrating slowly 1, 5
Monitor closely for worsening vitamin deficiencies when using bile salt sequestrants 1, 5

Rifaximin remains first-line treatment for methane-dominant SIBO, although this citation is from a less preferred source 4
Combination therapy (antibiotics plus probiotics after treatment) may be effective, although this citation is from a less preferred source 4