Epidemiology and Management of Acute, Uncomplicated Septic Arthritis and Osteomyelitis: Spanish Multicenter Study.

Background: Acute osteoarticular infection (OAI) is a potentially severe disease. The aim of this study was to evaluate the etiology, clinical characteristics and therapeutic approach of OAI in children in Spain.

Methods: Medical records from children <14 years with OAI from 25 hospitals between 2008 and 2012 were reviewed. Confirmed osteomyelitis (OM) and septic arthritis (SA) required a positive bacterial isolate; otherwise, they were considered probable. Probable SA with <40,000 cells/mm in joint fluid was not included.

Results: A total of 641 children were evaluated. Two hundred and ninety-nine cases (46%) were OM, 232 (36%) SA, 77 (12%) osteoarthritis and 33 (5%) spondylodiscitis. Children with OM were older (63 vs. 43 months for SA; P < 0.001). Magnetic resonance imaging and bone scintigraphy had the highest yield for OM diagnosis (94%). Arthrocentesis was performed in 96% of SA. A microorganism was isolated in 246 patients (38%: 33% OM vs. 55% SA; P < 0.001): Staphylococcus aureus was the most common (63%), followed by Kingella kingae (15%) and Streptococcus pyogenes (9%). Ninety-five percent of children initially received IV antibiotics, mostly cefotaxime + cloxacillin (60%) or cloxacillin (40%). Total treatment duration was 38 (±31) days for OM and 28 (±16) days for SA (P < 0.0001). Twenty percent of children with OM (46% because of complications) and 53% with SA (95% initial arthrotomy) underwent surgery. Patients with SA were compared according to initial arthrotomy (n = 123) versus arthrocentesis (n = 109), and no clinical differences were observed, except for higher rate of hip SA in the former (50% vs. 9%; P < 0.001). Children with arthrocentesis had less sequelae [6.6% vs. 1%; P = 0.03, odds ratio = 0.58 (95% confidence interval: 0.45-0.76)], but not in the multivariate analysis.

Conclusions: This is the largest pediatric cohort of OAI in Spain. S. aureus was the most common isolate, although K. kingae was recovered in a high proportion of cases. Conservative management was applied in half of the patients. There was a low rate of sequelae, even with nonsurgical approaches.