A 65-year-old man presents to the emergency department with a two-day history of fever, headache, altered mental status, and vomiting. His past medical history is significant for renal transplantation secondary to polycystic kidney disease, hypertension, and diabetes. He takes aspirin, insulin, nifedipine, cyclosporine, and prednisone. He has no known drug allergies. His temperature is 39.2C (102.5F), pulse is 102/min, respirations are 18/min, and blood pressure is 120/75 mm Hg. He is alert but confused. Fundoscopy does not show any abnormalities. His neck is stiff. Lungs are clear to auscultation. He has a normal S1 and S2 with a II/IV systolic ejection murmur heard best in the right infraclavicular area. Complete blood count shows a WBC count of 17,000/cm3 with neutrophilic leukocytosis. His blood is drawn and sent for culture. Lumbar puncture is performed and the results are pending. Which of the following is the most appropriate empiric antibiotic therapy for this patient?
A. Ceftriaxone
B. Ceftriaxone and vancomycin
C. Cefotaxime and ampicillin
D. Ceftriaxone, vancomycin, and ampicillin
E. Ceftazidime and vancomycin