MSRA-1110

An 80-year-old man presents with a 2-week history of profuse loose stools and severe abdominal pain over the past 2 days. He has lost his appetite and is only tolerating small amounts of fluid over the past 24 hours. On examination, his heart rate is 118 bpm, respiratory rate is 22 breaths/min, temperature 38.1ºC and blood pressure is 104/74 mmHg. Significant left iliac fossa tenderness is noted. The patient is urgently admitted, and a stool culture confirms Clostridium difficile infection and severe colitis without perforation on imaging. What is the most appropriate treatment for this patient?