Osteomyelitis is most commonly caused by which organism?

Osteomyelitis is most commonly caused by which organism?

• A. Escherichia coli
• B. Staphylococcus aureus
• C. Pseudomonas aeruginosa
• D. Salmonella

Answer: (B)

Staphylococcus aureus is the most common cause of osteomyelitis because it is the most frequent organism encountered in bacteremia that seeds bone, and it has a combination of traits that let it establish bone infection quickly. It is a common skin commensal, so it readily enters the bloodstream after skin or soft-tissue infections and deposits in bone, especially in the metaphyseal regions with rich blood supply. Its virulence factors—adhesins to attach to bone, enzymes that break down tissue and spread, and the ability to form biofilms on implants or damaged bone—facilitate rapid invasion and persistence in bone tissue. While other organisms are important in certain contexts (for example, Salmonella in sickle cell disease, Pseudomonas in puncture wounds or hospital settings), Staphylococcus aureus remains the most frequent cause overall.

Staphylococcus aureus is the most common cause of osteomyelitis because it is the most frequent organism encountered in bacteremia that seeds bone, and it has a combination of traits that let it establish bone infection quickly. It is a common skin commensal, so it readily enters the bloodstream after skin or soft-tissue infections and deposits in bone, especially in the metaphyseal regions with rich blood supply. Its virulence factors—adhesins to attach to bone, enzymes that break down tissue and spread, and the ability to form biofilms on implants or damaged bone—facilitate rapid invasion and persistence in bone tissue. While other organisms are important in certain contexts (for example, Salmonella in sickle cell disease, Pseudomonas in puncture wounds or hospital settings), Staphylococcus aureus remains the most frequent cause overall.