The biochemical, microbiological and histological findings in native joint septic arthritis in adults

Abstract

Background Septic arthritis is an orthopaedic emergency with an incidence of 2 to 10 per 100 000 patients in the general population. Mortality rates between 3 and 29% can be expected. Local knowledge of microorganisms and antibiotic sensitivities will facilitate expedited and effective treatment. The aim of the study was to review and analyse the microbiological, histological and biochemical findings in patients taken to theatre for the purposes of treating a septic arthritis of native joints in adult patients at our institution. Methods A retrospective case series analysis was performed. We included only adult patients that were taken to theatre for treatment of a presumed septic joint. We excluded paediatric patients, joints distal to the elbow or ankle, and the spine. Preoperative blood tests and samples obtained intraoperatively for microbiological and histological testing were analysed. Inflammatory markers were compared against culture results. Bacteria trends and antibiotic sensitivities were assessed. Histological findings were analysed against positive cultures. Results In our study, 104 patients were taken to theatre for the treatment of presumed septic arthritis during the data collection period. Eighty-six (81%) were found to have septic arthritis based on cultures and/or histology. The knee was the most affected joint (67%). A regression analysis suggested that high erythrocyte sedimentation rate and high C-reactive protein levels were better predictors for septic arthritis compared to white cell count. Methicillin-sensitive Staphylococcus aureus (31%), Staphylococcus epidermidis (10%) and Enterobacter cloacae complex (8%) were the most common organisms identified. Multidrug-resistant organisms were cultured in 19% (9/48) cases, in the form of methicillin-resistant Staphylococcus aureus, Proteus mirabilis and Acinetobacter baumannii. Conclusion Septic arthritis remains a diagnostic challenge and organism and antibiotic patterns vary. We present a review and summary of all septic joints over a seven-year period at a tertiary level orthopaedic service.