This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Skeletal infections, Subject name: Anatomy
The most common organism causing osteomyelitis is 
Select and explain. 
A. E, coli, B. Pseudomonas, C. Klebsiella, D. Staph aureus
D: Staph aureus
Answer: D: Staph aureus 
Explanation: The most common organism in osteomyelitis in intravenous drug users is staphylococcus aureus. Pseudomonas aeruoginosa an otherwise unusual cause of osteomyelitis, is the second most frequently observed microorganism Refer Maheshwari 6th/e p 168