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Difficulty: MediumGastroenterology and Hepatology

A 22-year-old college student presents to the student health clinic complaining of severe abdominal cramping and bloody diarrhea for the past 2 days. He initially developed nausea and watery diarrhea 4 days ago after attending a campus cookout where he consumed a medium-rare hamburger. Over the last 48 hours, the diarrhea has become overtly bloody. His temperature is 37.1°C (98.8°F), blood pressure is 112/70 mmHg, and heart rate is 84/min. Physical examination reveals a non-distended abdomen with hyperactive bowel sounds and diffuse tenderness to palpation, but there is no guarding or rebound tenderness. Laboratory testing shows a hemoglobin level of 14.2 g/dL, a leukocyte count of 8,500/µL, and a platelet count of 210,000/µL. Serum creatinine is 0.9 mg/dL. Stool culture and Shiga toxin testing have been ordered. Which of the following is the most appropriate next step in management?

  1. Intravenous fluids and supportive careAnswer
  2. B
    Oral ciprofloxacin therapy
  3. C
    Intravenous piperacillin-tazobactam therapy
  4. D
    Oral trimethoprim-sulfamethoxazole therapy
  5. E
    Surgical consultation for exploratory laparotomy

Answer

Intravenous fluids and supportive care
This patient presents with acute, afebrile bloody diarrhea and severe abdominal cramps after consuming undercooked ground beef, a presentation highly suggestive of Shiga toxin-producing Escherichia coli (STEC) infection. The cornerstone of management for STEC enteritis is supportive care, particularly fluid and electrolyte replacement. Empiric antibiotic therapy is strictly contraindicated because it causes bacterial lysis and induces the expression of Shiga toxin genes, leading to massive systemic toxin release. This significantly elevates the risk of developing hemolytic uremic syndrome (HUS), a triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury.

Step-by-Step Solution

1
Analyze the clinical presentation and exposure history.
The patient has afebrile, acute bloody diarrhea and severe abdominal cramps following the consumption of undercooked ground beef.
This classic triad of symptoms and exposure history strongly suggests infection with Shiga toxin-producing Escherichia coli (STEC), such as E. coli O157:H7.
2
Evaluate the role of antimicrobial therapy in this specific infection.
Antibiotics are strictly contraindicated in suspected STEC infections.
Antibiotic administration causes bacterial cell lysis and increases the production and release of Shiga toxin, which substantially raises the risk of developing hemolytic uremic syndrome (HUS).
3
Determine the optimal immediate management strategy.
The patient should receive intravenous fluids and supportive care while awaiting stool study results.
Supportive care maintains hemodynamic stability and hydration without triggering dangerous toxin-mediated complications.

Key Concept

Management of suspected Shiga toxin-producing Escherichia coli (STEC) enteritis requires supportive care (hydration); empiric antibiotic therapy is contraindicated as it increases the risk of hemolytic uremic syndrome (HUS).
Estimated Time:1m 15s
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Topics

Gastroenterology and Hepatology

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