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: Surgery
[{'content': 'Most Commmon cause of chronic osteomyelitis ? \nSelect and explain. \nA. Staphylococcus aureus, B. Streptococcus pyogenes, C. Mycobacterium tuberculosis, D. Staphylococcus epidermidis', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Staphylococcus aureus Chronic osteomyelitis is nearly always a sequel to acute osteomyelitis. Occasionally infection is subacute or chronic from the begining. As with acute osteomyelitis, the most common causative organism is staphylococcus areus.", 'role': 'assistant'}]