Review Question - QID 212953

This patient has a diagnosis of septic arthritis. The most likely etiology of septic arthritis in this age group is Neiserria gonorrhoeae which presents with a negative synovial fluid aspiration greater than 50% of the time.

Gonococcal septic arthritis is by far the most common cause of monoarthritis in young sexually active adults. Teenagers likely will not be forthcoming about their sexual history so one must be suspicious. It affects females to males at a ratio of 3:1. The difference may be because women usually have a more asymptomatic clinical picture and present more often with untreated genitourinary tract infections. There is a characteristic triad of clinical components: migratory polyarthralgia, dermatologic lesions usually presenting as macules and papules, and tenosynovitis often affecting multiple joints simultaneously (particularly wrists, fingers, ankles, and toes), as well as systemic inflammatory symptoms.

Rice et al. perform a review of gonococcal arthritis. They report that septic arthritis caused by N. gonorrhoeae may be monarticular or pauciarticuar and is more commonly associated with positive synovial fluid cultures and negative blood cultures. They recommend initial treatment with ceftriaxone or another advanced cephalosporin until signs of symptoms have improved.

Garcia-De La Torre et al. performed a review of gonococcal and nongonococcal arthritis. They report that exposure to sexual encounters should raise suspicion of this type of arthritis and even though a positive Gram stain of synovial fluid is present in less than 50% of these patients, simultaneous cultures of cervix, urethra, and rectus should be obtained to augment the positive result, especially searching for the presence of N. gonorrhoea.

Figure A is an AP pelvis radiograph with no visible pathology. Figure B is an ultrasound demonstrating a hip joint effusion. Illustration A is a labeled ultrasound indicating the effusion. Illustration B is a table detailing the characteristics of gonococcal vs. nongonococcal arthritis (Garcia-De La Torre et al.).

Incorrect Answers:
Answer 1: Gram-negative diplococci would be indicative of N. gonorrhoea; however, it is not the most likely finding of the joint fluid.
Answer 2: Gram-positive cocci in clusters would be indicative of Staphylococcus aureus infection which is not as likely in this age group.
Answer 3: Rheumatoid factor is useful in diagnosing juvenile rheumatoid arthritis. It is not found in joint fluid.
Answer 5: Presence of negatively birefringent crystals would be diagnostic of gout.