Final answer:
Osteomyelitis is an infection of the bone or bone marrow, primarily caused by bacteria like Staphylococcus aureus, affecting both children and adults, with children's long bones being more susceptible due to vascularization.
Step-by-step explanation:
Osteomyelitis is the medical term for the infection of bone or bone marrow. It is a serious condition that can be either acute or chronic. The infection most often affects children, impacting long bones such as the femur due to their extensive blood supply which can spread the infection from other areas.
In adults, it is usually caused by direct introduction of bacteria through trauma or surgery. The primary cause of osteomyelitis is Staphylococcus aureus (S. aureus), but other bacteria like M. tuberculosis and Pseudomonas aeruginosa can also be responsible depending on which bones are involved.