small intestinal bacterial overgrowth

Etiology

• blind loop syndrome
  • gastrectomy
  • Roux-en-Y gastric bypass
  • afferent loop dysfunction post-gastrojejunostomy
• hypochlorhydria
  • post-operative
  • atrophic gastritis, pernicious anemia
    • vitamin B12 deficiency
  • antacids
    • proton pump inhibitors
    • H2-receptor antagonists
  • vagotomy
• structural defects
  • diverticulosis of the small intestine
  • persistent small intestine dilation due to distal small intestine stricture
    • Crohn's disease
    • NSAIDs
    • postoperative complication
  • radiation enteropathy
• intestinal dysmotility syndromes
  • diabetes mellitus
  • scleroderma
  • intestinal pseudo-obstruction
  • autonomic neuropathy
  • amyloidosis
  • systemic myopathies
• short bowel syndrome
• surgical resection of ileocecal valve
• advanced age
• immunodeficiency
  • IgA deficiency
  • common variable immunodeficiency
• celiac disease
• pancreatic insufficiency
• biliary obstruction
• cirrhosis

Clinical manifestations

• diarrhea
• bloating
• flatulence
• weight loss

Laboratory

• hydrogen breath test
• 14C cholylglycine breath test
• serum vitamin B12 (vitamin B12 deficiency)
• serum folate is increased

Differential diagnosis

• celiac disease
  • serum vitamin B12 & serum folate low
• lactose intolerance
  • not associated with macrocytosis, a high serum folate & low serum vitamin B12
• pancreatic insufficiency
  • unless severe, unlikely to diminish vitamin B12 absorption
  • not comment regarding effect on serum folate

Management

• rifaximin 1st line
• trial of empiric antibiotics
  • Bactrim DS, tetracycline, metronidazole
  • ciprofloxacin, amoxicillin clavulanate

More general terms

• intestinal disease

More specific terms

• bacterial overgrowth syndrome

Additional terms

• blind loop syndrome; stagnant loop syndrome; stasis syndrome
• intestinal bacteria (flora)