SIBO is a pathologically excessive growth of bacteria in the small intestine.

Etiology

• Structural abnormalities
  • Postsurgical complications, e.g.:
    • Short bowel syndrome
    • Blind loop syndrome: bacterial overgrowth in the bypassed intestinal segment (blind loop), e.g., due to gastrectomy
    • Adhesions
• Motility disorders
  • Irritable bowel syndrome (IBS)
  • Paralytic ileus, e.g., due to opiate use
  • Systemic disorders, e.g., diabetic autonomic neuropathy, systemic sclerosis, amyloidosis
• Biochemical abnormalities
  • Achlorhydria, e.g., due to atrophic gastritis
  • Chronic pancreatitis
• Immune disorders
  • Common variable immunodeficiency
  • Selective IgA deficiency
  • HIV

Pathophysiology

• The following result from bacterial overgrowth.
  • ↑ Deconjugation of the bile acids
  • ↑ Production of folate
  • ↓ absorption of vitamin B12, fat-soluble vitamins, zinc, and iron

Clinical features

• Bloating, flatulence
• Chronic watery diarrhea
• Severe: steatorrhea, vitamin deficiencies

Diagnostics

Treatment

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