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: Pathology
Causative organism in acute bacterial endocarditis is - 
Select and explain. 
A. Staphylococcus aureus, B. Streptococcus viridans, C. Pneumococcus, D. Streptococcus pyogenes
A: Staphylococcus aureus
Answer: A: Staphylococcus aureus 
Explanation: Acute osteomyelitis may be : -

i. Primary (hematogenous):- Organisms reach the bone through the bloodstream.
ii. Secondary:- Organism gain energy directly through wound such as in compound fractures or surgical operation,

Hematogenous osteomyelitis is the commonest form of osteomyelitis and most common source of bone and joint infection is hematogenous.
it is caused most commonly by Staphylococcus aureus.
Other causative organisms are streptococcus, pneumococcus, and gram-negative bacilli.