Septic arthritis in adults

Abstract

Septic arthritis (SA) is a medical emergency with mortality of around 15%. Presentation is usually monoarticular but in more than 10% SA affects two or more joints. Symptoms include rapid-onset joint inflammation with systemic inflammatory responses but fever and leucocytosis may be absent at presentation. Treatment according to British Society of Rheumatology/British Orthopaedic Association (BSR/BOA) guidelines should be commenced if there is a suspicion of SA. At-risk patients include those with primary joint disease, previous SA, recent intra-articular surgery, exogenous sources of infection (leg ulceration, respiratory and urinary tract), and immunosupression because of medical disorders, intravenous drug use or therapy including tumour necrosis factor (TNF) inhibitors. Synovial fluid should be examined for organisms and crystals with repeat aspiration as required. Most SA results from haematogenous spread-sources of infection should be sought and blood and appropriate cultures taken prior to antibiotic treatment. Causative organisms include staphylococcus (including meticillin-resistant Staphylococcus aureus, MRSA), streptococcus, and Gram-negative organisms (in elderly patients), but no organism is identified in 43%, often after antibiotic use before diagnosis. Antibiotics should be prescribed according to local protocols, but BSR/BOA guidelines suggest initial intravenous and subsequent oral therapy. Medical treatment may be as effective as surgical in uncomplicated native SA, and can be cost-effective, but orthopaedic advice should be sought if necessary and always in cases of infected joint prostheses. In addition to high mortality, around 40% of survivors following SA develop limitation of joint function. Guidelines provide physicians with treatment advice aiming to limit mortality and morbidity and assist future research.