Characteristics and outcomes of community-onset septic arthritis in adults.

BACKGROUND AND PURPOSE Failure to recognize and to appropriately treat septic arthritis results in substantial morbidity rates. This study compared the demographic characteristics, risk factors, and outcomes of patients with community-onset septic arthritis due to Gram-positive and Gram-negative bacteria. METHODS The medical charts of 51 adults with culture-proven community-onset septic arthritis treated at a tertiary medical center in northern Taiwan from January 1, 2004 through December 31, 2007 were retrospectively reviewed. The demographic data and clinical features were analyzed. RESULTS There were 39 patients with septic arthritis caused by Gram-positive cocci (76.4%) and 12 with septic arthritis caused by Gram-negative bacteria (23.6%). The most common pathogen was Staphylococcus aureus (n = 30; 58.9%). The most frequently involved joint was the knee (n = 33; 63.5%). By multivariate logistic regression analysis, age (odds ratio [OR], 1.07; 95% confidence interval [CI], 1.01-1.13; p = 0.024) and range of motion limitation (OR, 8.23; 95% CI, 1.14-59.49; p = 0.037) were independent predictive factors for septic arthritis caused by Gram-positive cocci. Diabetes mellitus with end-organ damage (OR, 0.03; 95% CI, 0.00-0.39; p = 0.007) and malignancy (OR, 0.04; 95% CI, 0.00-0.66; p = 0.025) were negative predictive factors for septic arthritis caused by Gram-positive cocci. There were no significant differences in outcomes for patients with Gram-positive and Gram-negative septic arthritis. CONCLUSIONS In adult patients with community-onset septic arthritis, older age and limited range of motion predict for Gram-positive cocci as the causative pathogen, while underlying diabetes mellitus with end-organ damage and malignancy predict for Gram-negative bacteria as the causative pathogen.