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Key Features

  • Overgrowth of bacteria in normally sterile segments of small bowel; may result in malabsorption of fat with steatorrhea

  • Causes include

    • Gastric achlorhydria

    • Anatomic abnormalities of the small intestine with stagnation (afferent limb of Billroth II gastrojejunostomy, resection of ileocecal valve, small intestine diverticula, obstruction, blind loop)

    • Small intestine motility disorders (vagotomy, scleroderma, diabetic enteropathy, chronic intestinal pseudo-obstruction)

    • Gastrocolic or coloenteric fistula (Crohn disease, malignancy, surgical resection)

    • Miscellaneous disorders

Clinical Findings

  • Many patients are asymptomatic

  • Flatulence, weight loss, abdominal pain, diarrhea, and sometimes steatorrhea

  • May also be present in a subset of patients with irritable bowel syndrome

  • Advanced cases associated with deficiencies of iron or vitamins A, D, and B12

Diagnosis

  • Stool fecal fat: corroborates presence of steatorrhea

  • Small bowel CT or MR enterography or barium radiography: identifies mechanical factors predisposing to intestinal stasis

  • Small intestinal biopsy

    • Excludes other mucosal malabsorptive conditions (eg, celiac disease)

    • Detects intestinal inflammation

  • Aspirate and culture of proximal jejunal secretion

    • > 105 organisms/mL establishes the diagnosis

    • However, this test is not widely available

  • Noninvasive breath tests

    • Reported to have a sensitivity of 60–90% and specificity of 85% compared with jejunal cultures

    • Some studies confirm a high rate (up to 50%) of false-positive breath test results due to misinterpretation of bacterial fermentation

Treatment

  • Correct the anatomic defect when possible

  • Ciprofloxacin, 500 mg twice daily orally, norfloxacin, 400 mg twice daily orally, amoxicillin clavulanate, 875 mg twice daily orally, or combination of metronidazole, 250 mg three times daily orally, and trimethoprim-sulfamethoxazole 160/800 mg twice daily orally, or cephalexin, 250 mg four times daily orally, for 1–2 weeks

  • Rifaximin, 400 mg three times daily orally, is a nonabsorbable antibiotic that is effective and appears to have fewer side effects than systemic antibiotics

  • If symptoms recur off antibiotics, cyclic therapy (eg, 1 week of every 4) may be sufficient

  • Avoid continuous antibiotics to prevent bacterial antibiotic resistance

  • Octreotide in small doses may be of benefit

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