Background: In the management of pediatric osteomyelitis or septic arthritis, delay in treatment may affect outcome, while receipt of antibiotics prior to culture may affect culture results. We aimed to determine if pathogen identification decreased in cultures that were pretreated with antibiotics. Methods: We conducted a retrospective cohort study of 584 hospitalized children between 30 days and 18 years of age admitted to two tertiary children’s hospitals. Logistic regression assessed the effect of antibiotic duration on blood, bone, joint aspirate, and “other” culture positivity. Results: Overall, 42% of blood cultures, 70% of bone cultures, 39% of joint cultures, and 70% of “other” cultures were positive. Compared with children who did not receive antibiotics prior to culture, there were no significant differences in odds of a positive culture in children whose cultures were pretreated with antibiotics for any of the culture types [OR (95% CI) 0.90 (0.56–1.44) for blood cultures, 0.77 (0.25–2.34) for bone cultures, 0.71 (0.39–1.28) for joint cultures, 1.18 (0.58–2.41) “for other” cultures; all p > 0.05]. Furthermore, the duration (hours) of antibiotics in the pretreated cultures was also not a significant predictor of culture positivity (OR ranged from 0.99–1.00 for all cultures, p > 0.05). Conclusions: Culture positivity was not associated with antibiotic pretreatment in any of the samples, even for longer duration of antibiotics prior to culture, though the small sample size of subgroups is an important limitation. In pediatric patients hospitalized with osteomyelitis and/or septic arthritis, early initiation of antibiotics may not affect culture positivity.

This study sought to assess clinical characteristics and differences in outcomes between children with Methicillin-resistant Staphylococcus aureus (MRSA) and Methicillin-sensitive Staphylococcus aureus (MSSA) osteomyelitis or septic arthritis and whether initial antibiotic regimen affects patient outcomes. We analyzed records of children ages 15 days to 18 years admitted between 2009 and 2016 to two tertiary children’s hospitals who were diagnosed with an osteoarticular infection and had a microorganism identified. A total of 584 patients met inclusion criteria, of which 365 (62.5%) had a microbiological diagnosis. MSSA was the most common pathogen identified (45.5%), followed by MRSA (31.2%). Compared to MSSA, patients with MRSA had a higher initial C-reactive protein and longer hospitalization. Patients whose initial antibiotic regimens included vancomycin had a longer hospitalization than those initiated on clindamycin without vancomycin, even after removing sicker patients admitted to the pediatric intensive care unit. While MRSA was associated with increased severity of osteoarticular infections compared to MSSA, the incidence of MRSA has been declining at our institution. Patients with longer lengths of stay were more likely to be on vancomycin. Clindamycin should be considered in the initial antibiotic regimen for osteomyelitis and septic arthritis with ongoing surveillance of local microbiology and outcomes.