Common Septic Arthritis exam questions for medical finals, OSCEs and MRCP PACES
What are common organisms causing septic arthritis?
- Staph aureus
- Neisseria gonorrhoeae (in the sexually active)
- Haemophilus (in children, but rare due to vaccination)
- The elderly and people with chronically inflamed joints are prone to infection with unusual organisms.
- Lyme disease (Borellia burgdorferi) can cause an inflammatory arthritis
What investigations should be done in suspected septic arthritis?
- Bloods (especially for WCC, CRP and ESR)
- Blood cultures
- Aspirate joint and
- Send the fluid for URGENT microscopy, culture and crystals
- Gram stain positive in only 50%, synovial fluid growth positive in 90%
- MUST be done prior to starting antibiotics
- Swabs from skin wounds and the throat, sputum and urine
- Joint X-ray (baseline)