Impact of antibiotic pretreatment on cultures in children with osteomyelitis and septic arthritis: a retrospective review.

backgroundIn 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.

methodsWe 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.

resultsOverall, 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).

conclusionsCulture 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.