What diagnostic steps are used to diagnose septic arthritis due to gonorrhea?

• A. X-ray
• B. Serum CRP
• C. Joint aspiration and NAAT (gonorrhea)
• D. MRI

Answer: (C)

Diagnosing gonococcal septic arthritis relies on directly identifying Neisseria gonorrhoeae from the affected joint. The key step is joint aspiration to obtain synovial fluid for analysis, then testing that fluid with nucleic acid amplification tests for gonorrhea. This is the most reliable way because gonococcal arthritis can often be culture-negative and Gram stains may be unrevealing, whereas NAATs are highly sensitive for detecting the organism. In practice, clinicians also test mucosal sites (such as urine, throat, cervical, or rectal swabs) with NAAT, since gonorrhea commonly involves these sites and supports diagnosis when joint fluid results are inconclusive. Imaging like X-ray or MRI can document joint involvement and damage but does not establish the organism causing the arthritis, and CRP is a non-specific inflammatory marker rather than a diagnostic tool for gonorrhea.