The most common etiologic agent of septic arthritis in adults younger than 30 years of age is:
Neisseria gonorrhoeae.
Staphylococcus aureus.
The correct answer and explanation is:
The correct answer is Neisseria gonorrhoeae.
Explanation:
Septic arthritis is a severe joint infection that is commonly caused by bacterial pathogens. In adults under the age of 30, Neisseria gonorrhoeae is the most common etiologic agent of septic arthritis. This is particularly true in sexually active individuals, as the bacterium is primarily transmitted through sexual contact.
Neisseria gonorrhoeae is a gram-negative bacterium that causes gonorrhea, a sexually transmitted infection. When it infects the joints, it can lead to a condition called gonococcal septic arthritis, which often affects multiple joints, including the knees, wrists, and ankles. It typically presents as an acute, painful, and swollen joint, often with fever. Gonococcal septic arthritis is more common in young adults, especially those with risk factors like multiple sexual partners or unprotected sex.
The pathogen is able to invade and replicate in synovial tissues, leading to inflammation, pain, and the potential for permanent joint damage if not treated promptly. The diagnosis is often confirmed by identifying Neisseria gonorrhoeae in joint fluid obtained via aspiration or through blood cultures.
While Staphylococcus aureus is the most common cause of septic arthritis in the general adult population, particularly in older individuals or those with chronic medical conditions, Neisseria gonorrhoeae remains the predominant cause in sexually active young adults. Staphylococcus aureus is a gram-positive bacterium that can also cause septic arthritis, but it is more commonly associated with trauma, surgery, or the presence of underlying conditions like diabetes or immunosuppression.
Effective treatment of gonococcal septic arthritis typically involves a combination of antibiotics, including third-generation cephalosporins like ceftriaxone. Prompt treatment is essential to prevent joint destruction and other complications.