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Difficulty: EasyGastroenterology and Hepatology

A 71-year-old resident of a long-term care facility is evaluated for a three-day history of frequent, watery bowel movements and mild abdominal cramping. The patient recently completed a 7-day course of oral ciprofloxacin for an uncomplicated urinary tract infection. Temperature is 37.7°C (99.9°F), blood pressure is 120/78 mmHg, and pulse is 90/min. Physical examination reveals mild, diffuse abdominal tenderness without rebound or guarding. Laboratory studies show a leukocyte count of 14,000/mm³. A stool nucleic acid amplification test is positive for Clostridioides difficile. Which of the following is the most appropriate pharmacotherapy for this patient?

  1. A
    Intravenous ceftriaxone
  2. B
    Intravenous vancomycin
  3. C
    Oral metronidazole
  4. Oral fidaxomicinAnswer
  5. E
    Oral rifaximin

Answer

Oral fidaxomicin
The correct option is oral fidaxomicin. The patient is presenting with a first episode of non-fulminant Clostridioides difficile infection (CDI), characterized by recent antibiotic use, watery diarrhea, and a positive stool toxin test without signs of shock or toxic megacolon. Current clinical guidelines recommend treating an initial episode of non-fulminant CDI with either oral fidaxomicin or oral vancomycin. Fidaxomicin is a macrocyclic antibiotic that is bactericidal against C. difficile, has minimal systemic absorption, and spares normal gut flora more effectively than vancomycin, leading to lower recurrence rates.

Step-by-Step Solution

1
Identify the underlying diagnosis from the clinical presentation and laboratory findings.
The patient has acute watery diarrhea, mild leukocytosis, and a positive stool test following a recent course of antibiotics, confirming an initial episode of Clostridioides difficile infection.
Establishing the correct infectious etiology is required before selecting targeted antimicrobial therapy.
2
Determine the severity of the infection to guide treatment selection.
The patient lacks hypotension, shock, ileus, or toxic megacolon, categorizing this as a non-fulminant episode.
Treatment guidelines differ significantly for non-fulminant versus fulminant Clostridioides difficile infection.
3
Select the most appropriate evidence-based pharmacotherapy for the determined severity.
Oral fidaxomicin (or oral vancomycin) is indicated as the first-line agent.
Current infectious disease guidelines prioritize these agents over older therapies due to higher initial cure rates and a reduced risk of disease recurrence.

Key Concept

The first-line treatment for an initial episode of non-fulminant Clostridioides difficile infection is oral fidaxomicin or oral vancomycin.
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Topics

Gastroenterology and Hepatology

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