A 65-year-old woman is hospitalized for acute diarrhea and abdominal cramping after completing a course of clindamycin for a dental infection. Laboratory tests confirm the presence of Clostridioides difficile toxin in her stool. Her medical history includes hypertension and chronic kidney disease. She has had two previous episodes of C. difficile-associated diarrhea (CDAD) in the past year, both treated with oral vancomycin. Which of the following treatments is most appropriate for this patient?
