A 55-year-old man comes to the emergency department due to a 3-day history of abdominal cramps and diarrhea. He has had 5-7 watery stools a day, including at night. Three weeks ago, the patient was hospitalized for a perforated peptic ulcer that was complicated by peritonitis; he received antibiotics and underwent abdominal washout and distal gastrectomy. The initial postoperative course was uncomplicated. Temperature is 38.3 C (100.9 F), blood pressure is 116/74 mm Hg, and pulse is 96/min. Abdominal examination shows mild distension and diffuse tenderness. Bowel sounds are normal. The surgical wounds are clean, intact, and without discharge. Which of the following is the most likely cause of this patient's diarrhea?

Question

A 55-year-old man comes to the emergency department due to a 3-day history of abdominal cramps and diarrhea.  He has had 5-7 watery stools a day, including at night.  Three weeks ago, the patient was hospitalized for a perforated peptic ulcer that was complicated by peritonitis; he received antibiotics and underwent abdominal washout and distal gastrectomy.  The initial postoperative course was uncomplicated.  Temperature is 38.3 C (100.9 F), blood pressure is 116/74 mm Hg, and pulse is 96/min.  Abdominal examination shows mild distension and diffuse tenderness.  Bowel sounds are normal.  The surgical wounds are clean, intact, and without discharge.  Which of the following is the most likely cause of this patient's diarrhea?

Quizplus · Accepted Answer

Explanation: This patient who recently received antibiotics during hospitalization for a perforated peptic ulcer now has a low-grade fever, abdominal cramping and tenderness, and profuse watery diarrhea, most likely due to Clostridioides difficileinfection (CDI). Profuse watery diarrhea (≥3 loose stools/24 hr) is the hallmark symptom of CDI, which is suspected when major risk factors (eg, recent antibiotic use, recent hospitalization) are present. C difficile is a spore-forming, gram-positive, anaerobic bacterium transmitted via the fecal-oral route. After being ingested, the hardy, antibiotic-resistant spores germinate in the colon to become fully functional bacilli. Typically, normal colonic flora (eg, Bacteroides) suppresses the overgrowth of C difficile bacilli, but antibiotics can disrupt the normal colonic flora, leading to unchecked C difficileproliferation. Pathology is mediated by the release of C difficile exotoxins (ie, toxin A, toxin B) that cause inflammation and mucosal injury. (Choice A) Some distal gastrectomy procedures (eg, Billroth II) create a blind loop of small intestine that can experience bacterial overgrowth, especially if partial obstruction (eg, due to intraabdominal adhesion) subsequently develops. Small intestinal bacterial overgrowth can cause abdominal discomfort and watery diarrhea; however, the abdomen is usually normal (vs diffusely tender) on examination, and fever is unexpected. Billroth II (Choice B) Colonic ischemia may occur if a perforated ulcer leads to peritonitis, hemodynamic instability, and hypoperfusion of the mesenteric vasculature. Although acute colonic ischemia can cause abdominal cramping and diarrhea, the diarrhea is typically bloody (vs watery), and symptoms usually occur within hours of the hypoperfusion episode (vs 3 weeks later). (Choice D) Pyloric sphincter bypass or resection (eg, distal gastrectomy) may result in rapid emptying of gastric contents (hyperosmolar chyme) into the small intestine. The resulting fluid shifts (intravascular → intraluminal) can cause dumping syndrome presenting with abdominal cramps and diarrhea. However, symptoms typically occur shortly after meals, not during the night, and include vasomotor manifestations (eg, diaphoresis, palpitations). (Choice E) Injury to the vagus nerve during gastric surgery (eg, distal gastrectomy) can result in gastroparesis. The resulting delayed gastric emptying can cause abdominal pain and distension, but early satiety, nausea, and vomiting are commonly also present. Fever is unexpected. Educational objective: Clostridioides difficile is transmitted via the fecal-oral route. Ingested spores germinate in the colon to become fully functional bacilli and may proliferate unchecked when the normal colonic flora is disrupted (eg, antibiotic use). Profuse watery diarrhea (≥3 loose stools/24 hr) is the hallmark of C difficile infection. References: Clostridioides difficile biology: sporulation, germination, and corresponding therapies for C. difficile infection. (http://www.ncbi.nlm.nih.gov/pubmed/29473021)

A 55-Year-Old Man Comes to the Emergency Department Due to a 3-Day