Duration of antibiotic therapy and erythrocyte sedimentation rate predict blood culture results in children with acute osteomyelitis

Blood cultures are routinely performed for microbiological diagnostic purposes in acute hematogenous osteomyelitis (AHO); however, the blood culture positivity rate is less than 50%. This retrospective study aimed to identify indicators to distinguish blood culture outcomes in children with AHO from July 2017 to 2024. Patients were stratified based on the results of blood cultures. The age, sex, duration of symptoms, duration of antibiotic therapy before blood culture, location of the lesion, maximum temperature, and inflammatory indexes from admission were reviewed. The efficacy of each index in diagnosing negative blood cultures was also determined according to the receiver operator curves. Logistic regression analysis was used to determine the independent risk factors for blood culture negativity. Among 75 patients, 47 had negative and 28 had positive cultures. No significant differences were found in age, sex, symptom duration, or leukocyte count. However, maximum temperature, duration of antibiotic therapy before culture, neutrophil count, C-reactive protein, and erythrocyte sedimentation rate (ESR) showed significant differences. Logistic regression identified antibiotic therapy duration >2.5 days (OR = 6.383, 95% CI: 1.720-23.680) and ESR <41.5 mm/h (OR = 12.377, 95% CI: 2.042-75.015) as independent risk factors for negative cultures. AHO patients with either of these factors are more likely to have negative blood cultures. For such children, early invasive procedures to obtain pus or tissue for culture should be considered.