A 75-year-old male with a history of recent hospitalization for pneumonia, treated with broad-spectrum antibiotics, presents with profuse watery diarrhea (10-15 times per day), abdominal cramping, and a low-grade fever. Stool toxin assay for Clostridioides difficile is positive. His creatinine is 1.8 mg/dL (baseline 1.0 mg/dL), and WBC count is 18,000/µL. What is the most appropriate initial treatment?
✓ Correct Answer: Option C
Given the patient's elevated WBC and rising creatinine, this is considered a severe C. difficile infection. Oral vancomycin is the preferred initial treatment for severe C. difficile infection. Oral metronidazole is less effective. IV vancomycin is not effective for C. difficile as it does not reach the colon.