A 25-year-old man comes to the emergency department in the afternoon due to the sudden onset of abdominal cramps, nausea, and 6 or 7 episodes of vomiting over the past 3 hours. He has had no diarrhea or fever. Yesterday, the patient went on a day-long hike in a nearby forest and had dinner at a Chinese restaurant with friends. Today, he reheated some of the leftover noodles and rice for lunch. None of his friends developed similar symptoms. The patient took amoxicillin 4 weeks ago for acute sinusitis but otherwise has no medical history. Temperature is 37.1 C (98.8 F), blood pressure is 110/80 mm Hg, and pulse is 90/min. The abdomen is soft and nontender with no organomegaly. Which of the following is the most likely cause of this patient's current condition?

Question

A 25-year-old man comes to the emergency department in the afternoon due to the sudden onset of abdominal cramps, nausea, and 6 or 7 episodes of vomiting over the past 3 hours.  He has had no diarrhea or fever.  Yesterday, the patient went on a day-long hike in a nearby forest and had dinner at a Chinese restaurant with friends.  Today, he reheated some of the leftover noodles and rice for lunch.  None of his friends developed similar symptoms.  The patient took amoxicillin 4 weeks ago for acute sinusitis but otherwise has no medical history.  Temperature is 37.1 C (98.8 F), blood pressure is 110/80 mm Hg, and pulse is 90/min.  The abdomen is soft and nontender with no organomegaly.  Which of the following is the most likely cause of this patient's current condition?

Quizplus · Accepted Answer

11ec25c8_d451_cc5f_bc81_556d84efd42a_MD0003_00 This patient had reheated rice and quickly developed abdominal cramps, nausea, and vomiting, suggesting a foodborne illness caused by Bacillus cereus enterotoxin. B cereus proliferates in starches (eg, rice) that have been reheated or left at room temperature for extended periods. Enterotoxins are generated in the contaminated food and rapidly cause vomiting after ingestion (usually within 1-6 hours). Diarrhea and fever may occur but are less common. Symptoms are usually self-limited and resolve completely within 24-48 hours. (Choice A) Bacterial invasion of the intestinal mucosa usually causes watery or inflammatory diarrhea (blood, mucus, fever), sometimes with systemic infection. Campylobacter jejuni, nontyphoidal salmonella, and Listeria monocytogenes all directly invade the intestinal mucosa. This patient had vomiting without diarrhea, making this pathologic mechanism unlikely. (Choice C) Colonization of the intestine with subsequent toxin production usually causes delayed symptoms (>1 day) and watery or inflammatory diarrhea. Clostridium difficile, Clostridium perfringens, and enterotoxigenic Escherichia coli all operate by this mechanism. This patient had vomiting without diarrhea shortly after consuming reheated rice, making a preformed toxin more likely. (Choice D) Giardia likely causes a blunting of microvilli, which results in watery, foul-smelling diarrhea. Infections may be foodborne but are more typically acquired from contaminated water. The incubation period is typically 7-14 days. This patient has no diarrhea, making this mechanism unlikely. (Choice E) Small intestine mucosal inflammation is likely to result in watery diarrhea due to disruptions in water reabsorption. This patient with vomiting alone is unlikely to have significant small intestine inflammation. Viral gastroenteritis usually causes a combination of vomiting and diarrhea. Educational objective: Bacillus cereus enterotoxin forms in starch products (eg, rice) that have been left at room temperatures for extended periods or reheated. Symptoms begin rapidly after ingestion, usually within 1-6 hours. Vomiting is the primary manifestation.

A 25-Year-Old Man Comes to the Emergency Department in the Afternoon