This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S., Subject name: Medicine
A 62-year-old man presents to the emergency department because of new symptoms of fevers, chills, and malaise. His past medical history is significant for a prosthetic aortic valve replacement 5 years ago because of aortic stenosis from a bicuspid valve.On physical examination, the blood pressure is 130/85 mm Hg, heart rate is 88/min, and temperature 38.5degC. He has a 2/6 systolic ejection murmur heard best at the aortic region and a mechanical second heart sound, but no other abnormalities on examination. Blood cultures are most likely to grow which of the following? 
Select and explain. 
A. fungi, B. bartonella, C. diphtheroid, D. Staphylococcus epidermidis
D: Staphylococcus epidermidis
Answer: D: Staphylococcus epidermidis 
Explanation: S. epidermidis is still the most frequent early and late cause of endocarditis in patients with prosthetic heart valves. The other organisms are seen less frequently in late prosthetic valve endocarditis.