A 70-year-old woman was recently treated for pneumonia with antibiotics. After 1 week on antibiotics, she started developing severe diarrhea of 6–7 loose, watery stools per day. The diarrhea has been present for 3 days. She also has a decreased appetite, feels nauseous, and has not been drinking a lot of fluids. She feels very weak and dizzy. She lives alone, so she called 911 and was brought to the emergency department. She is diagnosed with diarrhea, presumptive Clostridium difficile.