A 45-year-old woman comes to the office due to a 6-month history of abdominal bloating, excessive flatulence, and watery diarrhea. Past medical history is significant for long-standing type 1 diabetes mellitus managed with insulin. Vital signs are normal. Abdominal examination shows no abnormalities. Jejunal aspirate is obtained during upper gastrointestinal endoscopy by placing a sterile catheter; culture of the aspirate reveals 10,000 colony-forming units/mL of Bacteroides species. Which of the following is the most likely cause of this patient's current symptoms?

Question

A 45-year-old woman comes to the office due to a 6-month history of abdominal bloating, excessive flatulence, and watery diarrhea.  Past medical history is significant for long-standing type 1 diabetes mellitus managed with insulin.  Vital signs are normal.  Abdominal examination shows no abnormalities.  Jejunal aspirate is obtained during upper gastrointestinal endoscopy by placing a sterile catheter; culture of the aspirate reveals >10,000 colony-forming units/mL of Bacteroides species.  Which of the following is the most likely cause of this patient's current symptoms?

Quizplus · Accepted Answer

11ec160b_3cc6_b7dc_9249_89584c344629_MD0001_00 This patient has small intestinal bacterial overgrowth (SIBO), which presents with excessive intestinal gas (ie, bloating, flatulence) and diarrhea. Diagnosis is sometimes confirmed by quantitative culture of jejunal fluid; normal small intestine bacterial load is <1,000 colony-forming unit/mL. SIBO is caused by excessive bacterial proliferation in the small intestine, resulting in mucosal injury and fermentation of dietary carbohydrates. In normal individuals, migrating motor complexes cause intestinal peristalsis, which clears bacteria and reduces the reflux of colonic organisms into the small bowel. Patients with impaired gut motility (eg, long-standing diabetes mellitus with autonomic neuropathy) are at increased risk for SIBO, as are patients with anatomic (eg, bowel adhesions, intestinal blind loops from surgery) or fibrotic (eg, scleroderma, prior radiotherapy) disruptions of intestinal flow. Other patient factors contributing to SIBO include the following: Pancreatobiliary dysfunction: Bile acids have a detergent effect that disrupts bacterial membranes and increases exposure of organisms in ingested food particles to residual acid and proteolytic enzymes, which further deter growth. Lack of these protective factors (eg, chronic pancreatitis) increases the risk for SIBO (Choices A and C). Reduced gastric acid: Residual gastric acid impairs bacterial growth in the proximal small bowel. Achlorhydria from either atrophic gastritis or chronic proton pump inhibitor therapy predisposes to SIBO (Choice B). Blind gut loops/pouches: Blind-ended gut segments (eg, Roux-en-Y gastric bypass surgery) provide a protected environment for bacterial proliferation. Impaired enteric immunity: Secretory IgA and innate inflammatory mechanisms inhibit bacterial growth in the small bowel. Immunodeficiency states increase the risk for SIBO. (Choice E) The ileocecal valve prevents the reflux of colonic flora into the small intestine; mechanical disruption (eg, surgical resection) or functional incompetence can increase the risk for SIBO. Spasm of the valve would not increase SIBO risk. Educational objective: Small intestinal bacterial overgrowth is caused by bacterial proliferation in the small intestine. In normal individuals, intestinal peristalsis clears bacteria and reduces the reflux of colonic organisms into the small bowel; however, patients with impaired gut motility have an increased risk for bacterial overgrowth. __________ References: Small intestinal bacterial overgrowth: a primary care review. (http://www.ncbi.nlm.nih.gov/pubmed/27916156)

A 45-Year-Old Woman Comes to the Office Due to a 6-Month