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
[{'content': 'A patient with a prosthetic hea valve develops endocarditis eight months after Valve replacement. Most likely organisms responsible is \nSelect and explain. \nA. Staphylococcus aureus, B. Streptococcus Viridians, C. Salmonella faecalis, D. HACEK Group', 'role': 'user'}, {'content': 'Answer: A \nExplanation: 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.', 'role': 'assistant'}]