This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Orthopaedics
[{'content': 'Most common 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: Chronic osteomyelitis is nearly always a sequel to acute osteomyelitisOccasionally infection is subacute or chronic from the beginningAs with acute osteomyelitis, the most common causative organism is staphylococcus areus(Refer: Mohindra's Fundamentals of Ohopedics, 2nd edition, pg no. 283, 284)", 'role': 'assistant'}]