Duration of onset, body temperature and C-reactive protein can be used to predict the results of pus culture in children with acute osteomyelitis of long bones.

Background: With the application of PCR testing and Metagenomic Next-Generation Sequencing(mNGS), the detection rate of causative organisms in paediatric bone and joint infections has been greatly improved. The aim of our study is to identify some indicators that could be used to distinguish the culture results to optimize the use of PCR and mNGS.

Methods: In this study, a total of 117 cases of acute osteomyelitis of long bones in children who underwent pus culture were included. Patients were grouped as culture-negative (n:21) and culture-positive (n:96) groups according to the results of pus culture. Age, sex, duration of onset, maximum body temperature at onset, inflammatory indicators and D-dimer after admission were systematically collected for all patients and were compared for both groups. ROC curve (ROC) was used to evaluate the diagnostic efficiency of culture-negative. Logistic regression analysis was conducted to determine independent risk factors for culture-negative.

Results: There was no significant difference in age, sex and erythrocyte sedimentation rate between culture-negative group and culture-positive group (P > 0.05). The duration of onset was longer, and the temperature, white blood cells, neutrophils count, C-reactive protein and D-dimer were less elevated in culture-negative acute osteomyelitis (P < 0.05). Duration of onset, maximum body temperature at onset, white blood cell count, neutrophil count, C-reactive protein, and D-dimer have certain diagnostic efficacy in judging the efficacy of negative culture. Logistic regression analysis indicated that the duration of onset more than 6.5 days, the maximum body temperature at onset lower than 38.35℃ and C-reactive protein lower than 78.40 mg/L were independent risk factors for negative culture (P < 0.05).

Conclusions: Our study revealed that duration of onset more than 6.5 days, maximum body temperature at onset lower than 38.35℃ and C-reactive protein lower than 78.40 mg/L were independent risk factors for predicting negative culture. In children with this type of acute osteomyelitis, we recommend that the pus be tested by PCR or mNGS as a priority.