A 57-year-old woman is brought to the emergency department because of crampy abdominal pain and foul-smelling, watery diarrhea. One week ago, she underwent treatment of cellulitis with clindamycin. Her temperature is 38.4°C (101.1°F). Abdominal examination shows mild tenderness in the left lower quadrant. Her leukocyte count is 12,800/mm3. An enzyme immunoassay is positive for glutamate dehydrogenase antigen and toxins A and B. Treatment is begun with a drug that inhibits the sigma subunit of the RNA polymerase. The patient was most likely treated with which of the following drugs?

Question

Quizplus · Accepted Answer

Eductional Objective: Fidaxomicin is a first-line treatment for nonsevere C. difficile infection (e.g., WBC count < 15,000 cells/mL), as seen in this patient. Fidaxomicin is a bactericidal antibiotic that acts through inhibition of the RNA polymerase sigma subunit. Based upon recent revisions to guidelines, oral fidaxomicin is now considered a first-line treatment for nonsevere C. difficile infection. Fidaxomicin is administered less frequently than oral vancomycin, the other first-line treatment option for this condition, because it is significantly more expensive; however, fidaxomicin has been shown to lower recurrence rates.
In contrast to previous recommendations, metronidazole is now considered a second-line therapy.

A 57-Year-Old Woman Is Brought to the Emergency Department Because