This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
[{'content': 'Most common cause of aificial hea valve infection? \nSelect and explain. \nA. Staphylococcus aureus, B. Streptococcus mutans, C. Staph epidermidis, D. Pneumococcus', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., Staph epidermidis Most common cause of prosthetic valve endocarditis upto 12 months is coagulase - negative staphylococci (staph. epidermidis). Most common causes of infective endocarditis In native wall - Staphylococcus aureus. In early prosthetic valve (up to 12 months after valve surgery) - Staphylococcus epidermidis (coagulase negative staphylococcus). In late prosthetic valve (more than 12 months after valve surgery) - streptococcus viridans. In IV drug abusers - Staphylococcus aureus. In patients with intravenous catheter - coagulase negative staphylococci. After dental procedure (tooth extraction) - streptococcus mutans.", 'role': 'assistant'}]