What is the treatment for small intestinal bacterial overgrowth (SIBO)?

Treatment of Small Intestinal Bacterial Overgrowth (SIBO)

Rifaximin (550 mg twice daily for 1-2 weeks) is the first-line treatment for SIBO, effective in approximately 60-80% of patients with proven SIBO. 1

Diagnosis Before Treatment

• Combined hydrogen and methane breath testing is more effective at identifying SIBO than hydrogen testing alone 2, 1
• Glucose or lactulose breath tests are helpful non-invasive diagnostic tools, though they require further standardization 1
• Qualitative small bowel aspirate can help make the diagnosis when coordinated with local microbiology services 2, 1
• Testing rather than empirical treatment should be used whenever possible to help establish the cause for symptoms and support antibiotic stewardship 2

First-Line Antibiotic Treatment

• Rifaximin 550 mg twice daily for 1-2 weeks is the preferred first-line treatment as it is not absorbed from the GI tract, reducing risk of systemic resistance 2, 1
• Other equally effective antibiotics include:
  • Doxycycline 1
  • Ciprofloxacin (use with caution due to tendonitis risk with long-term use) 1
  • Amoxicillin-clavulanic acid 2, 1
  • Cefoxitin 2
• Metronidazole is less effective and should be considered a second-line option 2

Treatment Approaches for Recurrent SIBO

• For patients with reversible causes (e.g., immunosuppression during chemotherapy), usually one course of antibiotics is sufficient 2
• For recurrent SIBO, consider:
  • Low-dose, long-term antibiotics 2
  • Cyclical antibiotics 2
  • Recurrent short courses of antibiotics 2
  • Rotating antibiotics (particularly recommended for patients with systemic sclerosis) 2, 1

Management of Associated Symptoms

• Antidiarrheal medications like loperamide or diphenoxylate can be used for diarrhea associated with SIBO 1
• Bile acid sequestrants (cholestyramine or colesevelam) can manage bile salt malabsorption associated with SIBO 1
  • Start sequestrants at a low dose (e.g., ¼ sachet of cholestyramine) 2
  • Take at mealtimes, not on an empty stomach 2
  • Slowly increase dose over a few days to titrate to symptoms 2
  • Monitor for vitamin D deficiency (occurs in 20% of patients taking bile acid sequestrants) 2, 1
  • Check for deficiencies in fat-soluble vitamins (A, E, K) 2, 1

Dietary Considerations

• Consider a low-FODMAP diet for 2-4 weeks to reduce fermentable carbohydrates that feed bacterial overgrowth 3
• Ensure adequate protein intake while reducing fat consumption to minimize steatorrhea 3
• Consume complex carbohydrates and fiber from non-cereal plant sources to support gut motility 3
• Separate liquids from solids by avoiding drinking 15 minutes before or 30 minutes after eating 3

Pitfalls and Caveats

• Lack of response to empirical antibiotics may be due to resistant organisms, SIBO not being present, or concurrent disorders 2, 1
• Long-term use of metronidazole can cause peripheral neuropathy 1
• Long-term ciprofloxacin use can cause tendonitis and rupture 1
• Consider the risk of developing resistant organisms, including Clostridioides difficile 1
• Methane-producing organisms are particularly difficult to eradicate and often require more aggressive treatment approaches 4
• Discontinue probiotics during antimicrobial treatment as they may counteract therapeutic effects 4

Special Considerations for Specific Patient Populations

• For patients with systemic sclerosis, rotating antibiotics are specifically recommended 2, 1
• Use antibiotics cautiously in patients with preserved colon and short bowel syndrome 1
• Consider prokinetic agents after completing antimicrobial treatment to prevent recurrence 4