This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
A patient with a prosthetic hea valve develops endocarditis eight months after Valve replacement. Most likely organisms responsible is 
Select and explain. 
A. Staphylococcus aureus, B. Streptococcus Viridians, C. Salmonella faecalis, D. HACEK Group
A: Staphylococcus aureus
Answer: A: Staphylococcus aureus 
Explanation: Ref Harrison 19 th ed pg 816 Prosthetic valve endocarditis (PVE) arising within 2 months of valve surgery is generally nosocomial, the result of intraoperative contami- nation of the prosthesis or a bacteremic postoperative complication. This nosocomial origin is reflected in the primary microbial causes: S. aureus, CoNS, facultative gram-negative bacilli, diphtheroids, and fungi. The poals of entry and organisms causing cases beginning >12 months after surgery are similar to those in community-acquired NVE. PVE due to CoNS that presents 2-12 months after surgery often represents delayed-onset nosocomial infection. Regardless of the time of onset after surgery, at least 68-85% of CoNS strains that cause PVE are resistant to methicillin.