Small Intestine: Bacterial Overgrowth

Definition

• Excessive Bacteria Proliferation within the Small Intestine
• Also Known as Blind Loop Syndrome

Causes

• Stasis from Anatomic Abnormalities
  • Gastric Resection/Bypass
    • From Poor Afferent Limb Motility
    • Most Common After Antecolic Billroth II Reconstruction
  • Stricture
  • Diverticulosis
  • Blind Intestinal Loops
  • Reversed Segments
• Motility Disorders
  • Irritable Bowel Syndrome (IBS)
  • Intestinal Pseudo-Obstruction
  • Radiation Enteritis
  • Scleroderma
  • Narcotic Use
• Systemic/Metabolic Disorders
  • Diabetes
  • Pancreatic Insufficiency
  • Cirrhosis
  • Immunodeficiency/AIDS

Presentation

• Sx: Bloating, Flatulence, Abdominal Pain & Diarrhea
• Steatorrhea – From Bacterial Deconjugation of Bile
• Vitamin B12 Deficiency – Used by Bacteria
  • Results in Megaloblastic Anemia, Weakness & Ataxia

Diagnosis

• Carbohydrate Breath Test
  • Typically Preferred Test
  • Oral Carbohydrate Given Orally & Breath Tested Every 15 Minutes for 2 Hours
    • Uses Glucose, Lactulose or Xylose
  • Positive Findings:
    • Absolute Hydrogen Increase ≥ 20 ppm Over Baseline within 90 Minutes
    • Methane Level ≥ 10 ppm at Any Time
• Jejunal Aspirate
  • Requires Endoscopy to Obtain
  • Dx: Bacterial Concentration > 1,000 Colonies/mL

Treatment

• Initial Tx: ABX & Vitamin Replacement (Vitamin B12)
  • Goal of ABX to Reduce (Not Eradicate) Bacteria
  • First Choice: Rifaximin – Non-Absorbable Derivative of Rifamycin
  • Alternatives: Bactrim, Ciprofloxacin, Flagyl
  • Duration: 7-14 Days
• If Fails: Second Course of ABX
  • 40% Risk of Recurrence within 9 Months
  • Also Consider Trial of Elemental Diet (Medium-Chain Triglycerides More Easily Absorbed than Long-Chain)
• Surgical Management
  • Consider Surgery in the Setting of Past Bypass or Other Anatomical Causes
  • Goal of Surgery is to Address the Underlying Cause
  • Possible Interventions:
    • Shorten Afferent Limb
    • Small Bowel Resection
    • Stricturoplasty
    • Bypass