What is the likely etiologic agent in a septic joint in children?

• A. Pasturella multocida
• B. Eikinella corridens
• C. Staph aureus
• D. Strep pyogenes

Answer: (C)

In the context of septic arthritis in children, Staphylococcus aureus is a highly recognized etiologic agent. This bacterium is particularly significant due to its ability to cause a range of infections, including skin infections, pneumonia, and septic arthritis. In children, if a joint becomes infected, Staphylococcus aureus is often the predominant organism identified, attributed to its virulence and capacity to invade joint space, leading to inflammation and subsequent symptoms.

Staphylococcus aureus can cause both hematogenous spread—where the bacteria enter the bloodstream and localize in the joints—and direct inoculation if there is a breach in the skin, such as in trauma cases. Furthermore, it can affect joints in healthy children as well as those with underlying conditions, reinforcing its clinical relevance.

On the other hand, the other organisms listed, while they can cause infections, are less commonly associated with septic arthritis in the pediatric population or have distinct associations with other types of infections. For instance, Pasteurella multocida is primarily associated with animal bites, while Eikenella corrodens can result from human bites. Streptococcus pyogenes, although it can cause skin infections and throat infections, is not typically a leading cause of septic arthritis in children. Thus