A 68-year-old woman developed crampy abdominal pain with diarrhea after taking antibiotics for a dental procedure. She was treated for Clostridioides difficile infection (CDI) with oral vancomycin. Three weeks later, she developed similar symptoms and is treated for a relapse of CDI with vancomycin for 2 weeks. She now presents with her third episode of CDI 8 weeks after her initial infection. She is hemodynamically stable with minimal abdominal discomfort. She does not want to have surgery and would like to know other alternatives. What is the best next step in management?