Suspected septic arthritis in an adult: immediate workup and initial management?

• A. Urgent joint aspiration with Gram stain, culture, cell count; imaging as needed; start IV antibiotics after aspiration and proceed to irrigation/debridement if purulent.
• B. Start IV antibiotics before aspiration.
• C. Observe and wait.
• D. Joint aspiration is unnecessary.

Answer: (A)

In suspected septic arthritis, action focuses on rapid confirmation of infection and immediate source control to prevent joint destruction. The key step is urgent aspiration of the affected joint to obtain synovial fluid for Gram stain, cell count, and culture. The fluid analysis typically shows a markedly elevated white blood cell count with neutrophil predominance, and cultures (and Gram stain) help identify the culprit organism so therapy can be targeted. Imaging, such as ultrasound, can help guide aspiration or assess the extent of effusion, but it should not delay drainage.

Once the sample is obtained, start intravenous antibiotics right away to cover the common pathogens (especially Staphylococcus aureus, including MRSA) and to begin treatment promptly. Tailor the regimen when culture results come back. If the fluid is purulent or there’s evidence of ongoing infection, proceed to irrigation and debridement for definitive source control.

Delaying drainage or waiting without action risks rapid joint damage and sepsis. Starting antibiotics before aspiration can reduce the diagnostic yield, so the preferred sequence is obtain synovial fluid first, then initiate empiric IV antibiotics, with escalation or de-escalation based on culture results.