How useful are cultures and Gram stains in diagnosing gonococcal septic arthritis?
Unlike nongonococcal arthritis, the Gram stains of synovial fluid are positive in <25% in gonococcal arthritis. Cultures improve the diagnostic yield. Because urethritis is often asymptomatic, all patients should have a urine specimen as well as urethral/rectal/pharyngeal swabs sent for Gram stain, culture, and NAAT testing. Urethral smears and cultures are more useful in men (>90% sensitivity) than in women.
| Culture positivity in dGI | |
|---|---|
| Site | Isolation Rate |
| Genitourinary | 80% |
| Synovial fluid | 50% |
| Rectum | 20% |
| Pharynx | 10% |
| Blood | <30% |
| Skin | Rare |
