A 28-year-old man comes to the emergency department due to cramping abdominal pain, nausea, anorexia, and multiple episodes of loose stools for the last 2 days. The patient is a medical student who returned from rural Indonesia a week ago after volunteering at a hospital for a month. Several days into his travel, he experienced watery diarrhea that spontaneously resolved within a few days. After his return, he had fever and sore throat for which his primary care physician prescribed amoxicillin, which he finished taking 2 days ago. The patient has no chronic medical conditions, takes no other medications, and has no known allergies. His older brother has ulcerative colitis and his mother has hypertension.
Temperature is 39 C (102.2 F), blood pressure is 94/45 mm Hg, and pulse is 112/min and regular. The abdomen is soft and diffusely tender with maximum tenderness in the right lower quadrant. There is no rebound tenderness or rigidity.
Laboratory results are as follows:
Which of the following is the most likely cause of this patient's condition?

Question

A 28-year-old man comes to the emergency department due to cramping abdominal pain, nausea, anorexia, and multiple episodes of loose stools for the last 2 days.  The patient is a medical student who returned from rural Indonesia a week ago after volunteering at a hospital for a month.  Several days into his travel, he experienced watery diarrhea that spontaneously resolved within a few days.  After his return, he had fever and sore throat for which his primary care physician prescribed amoxicillin, which he finished taking 2 days ago.  The patient has no chronic medical conditions, takes no other medications, and has no known allergies.  His older brother has ulcerative colitis and his mother has hypertension.
Temperature is 39 C (102.2 F), blood pressure is 94/45 mm Hg, and pulse is 112/min and regular.  The abdomen is soft and diffusely tender with maximum tenderness in the right lower quadrant.  There is no rebound tenderness or rigidity.
Laboratory results are as follows:
 Which of the following is the most likely cause of this patient's condition?

Quizplus · Accepted Answer

11ec193a_961f_b2a5_853d_1951fd3e7002_MD0002_00 This patient's presentation (loose stools, abdominal pain, and significant leukocytosis developing days after antibiotic therapy) is most consistent with a diagnosis of Clostridium difficile infection (CDI). C difficile can present in a variety of ways (Table), but it usually colonizes normal gut flora altered by antibiotic use. Symptoms typically start during antibiotic therapy or 5-10 days afterward. Penicillins, fluoroquinolones, and clindamycin are most commonly associated with CDI; however, virtually any antibiotic may be involved. Lower abdominal tenderness, nausea, anorexia, and diarrhea with mucus or occult blood are common presentations. Diagnosis is suggested by clinical findings and recent antibiotic use; C difficile stool studies can be confirmatory. If there is high clinical suspicion, empiric treatment with oral vancomycin or fidaxomicin can be considered when awaiting test results. Fulminant disease (eg, hypotension, ileus, megacolon) requires the addition of intravenous metronidazole to high dose-vancomycin. Patients who are refractory to treatment may need further evaluation with colonoscopy or sigmoidoscopy; however, extreme caution should be used in patients with fulminant colitis due to perforation risk. (Choice A) Appendicitis most commonly presents with right lower quadrant abdominal pain, anorexia, and nausea/vomiting. However, this patient has had multiple episodes of loose stools over the past 2 days, and his abdomen is soft and diffusely tender (without rebound tenderness, making peritonitis less likely). This presentation makes infectious diarrhea with colitis more likely than appendicitis. (Choice C) Endotoxin-producing Shigella usually presents with bloody, mucoid diarrhea; fever; and abdominal pain. It resolves spontaneously in most patients. This patient's current episode of diarrhea is more likely due to C difficile given the high degree of leukocytosis; lack of bloody, mucoid diarrhea; and timing of symptoms shortly after antibiotic use. (Choice D) The majority (~90%) of Entamoeba histolytica infections are asymptomatic, whereas symptomatic patients have bloody diarrhea with abdominal pain. Symptoms usually have a subacute onset over 1-3 weeks. (Choice E) Inflammatory bowel disease usually presents with the gradual onset of diarrhea after previous self-limited episodes of rectal bleeding/diarrhea. This patient's timing of symptoms following antibiotic use makes this less likely. Educational objective: Clostridium difficile infection usually presents with multiple episodes of watery diarrhea after recent antibiotic use. Diagnosis is confirmed by stool studies, and treatment involves oral vancomycin or fidaxomicin. Patients refractory to treatment may need further investigation with sigmoidoscopy or colonoscopy. __________

A 28-Year-Old Man Comes to the Emergency Department Due to Cramping