Effect of Antibiotic Administration Before Joint Aspiration on Synovial Fluid White Blood Cell Count in Native Joint Septic Arthritis

Abstract

Background. This study was performed to assess the impact of preaspiration antibiotics on synovial fluid analysis and timing of operative treatment in native-joint septic arthritis. Methods. We performed a retrospective record review of adult patients from an urban level 1 trauma center with native joint septic arthritis in 2015–2019, identified by means of codes from the International Classification of Diseases (Ninth Revision and Tenth Revision). Univariate and multivariate analyses were performed to determine whether antibiotics were associated with lower synovial fluid white blood cell counts (WBCs), the percentage of polymorphonuclear neutrophil (PMNs), and rate of culture positivity. Secondary analysis included time elapsed from aspiration to surgery. Results. Of the 126 patients with septic joints included, nearly two-thirds (n = 80 [63.5%]) received antibiotics before joint aspiration. The synovial fluid WBC count, percentage of PMNs, and rate of culture positivity were significantly lower in patients who received preaspiration antibiotics than in those who did not (mean WBC count, 51 379.1/μL [standard deviation, 52 576.3/μL] vs 92 162.7/μL [59 330.6/μL], respectively [P