Patients with surgically treated culture-negative native joint septic arthritis have less severe disease and better outcomes

Background: Patients with culture-negative septic arthritis patients are often treated surgically but might be successfully managed medically. We compared clinical characteristics and outcomes in patients with culture negative and culture positive native joint monoarticular septic arthritis. Methods: This retrospective study included all patients age ≥18 years admitted to a single, tertiary-care hospital between 1998 and 2015 with native joint monoarticular SA and treated with antibiotics and surgery. Results: Of 306 patients, 85 had negative and 221 had positive cultures. Mean C-reactive protein (p <.01) and mean percentage of peripheral polymorphonuclear cells (p =.01) were higher in culture-positive patients who had higher intensive care unit admission rates (16.7% vs. 4.7%, respectively, [p <.01]), longer length of hospital stay (11.4 vs. 7.1 days, respectively, [p <.01]) and higher mortality rates within 30 days (0% vs. 5.5%, respectively,[p =.02]). Of culture-negative patients, 28.6% received an alternative diagnosis within one year. Logistic regression models showed that culture positive patients had an adjusted odds ratio for length of stay of 4.5 (2.69, 7.51), intensive care unit admission of 5.76 (1.31, 25.22), discharge to rehabilitation of 4.7 (2.28, 9.71) and an alternative diagnosis within one year of 0.05 (0.02, 0.15) compared to culture negative patients. Conclusion: Patients with culture-negative native joint septic arthritis had less severe disease, better outcomes and higher rates of alternative diagnosis within one year than patients with positive cultures.