Background: The study aims to use five common pathogenic bacteria in Fracture-related infection (FRI) to establish a simple and fast multiplex qPCR method for initially clinical FRI detection. Methods: A total of 66 patients with FRI and 24 noninfectious volunteers were enrolled. Results from tissue culture and multiplex qPCR were analyzed and compared. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), Youden Index and area under the ROC curve (AUC) of the two methods were calculated respectively. Results: For 66 FRI cases, tissue culture detected 63 cases (95.5%) and multiplex qPCR detected 56 cases (84.8%). Among the 24 control cases, 12.5% and 16.7% were detected positive by tissue culture and multiplex qPCR, respectively. The sensitivity and specificity of multiplex qPCR were 84.8% and 66.7%, while those of tissue culture were 95.4% and 87.5%, respectively. To 51 cases within the detection profile, five common pathogens of FRI, the sensitivity and specificity of PCR changed to 92.2% and 90.9%, respectively. Conclusion: The advantage of multiplex qPCR is short processing time (< 5h) and simple steps. The multiplex qPCR may provide a complemental method for clinical FRI detection due to the simplicity and rapidity.

Objectives: This study compared the results of bacterial culture from operation versus sinus tract samples in patients with fracturerelated infection (FRI), and examined the ability of bacterial culture in sinus tract to identify pathogenic bacteria. Methods: A retrospective analysis of 53 patients with FRI from June 2016 to June 2021 was done. Common infection sites were femur, tibiofibular, hip joint, and ankle. Samples collected in sinus tract and during the operation were sent for bacterial culture. Results were summarized and compared, respectively, with pathogenic bacteria. Results: In sinus tract bacterial culture, bacteria were found in 75.6% of culture samples. The top 3 bacteria presented were: Staphylococcus aureus (32.26%), Staphylococcus epidermis (12.90%), and Pseudomonas aeruginosa (8.06%). Bacterial culture from the sinus tract matched the result of intraoperative samples 67.30% of the time, while 51.50% matched the pathogenic bacteria. Conclusion: Bacterial culture of sinus tract samples is not recommended as the basis for identifying pathogenic bacteria. Stopping antibiotic 2 weeks before operation, taking multiple samples at different sites, and sending multiple samples for bacterial culture are good ways to improve pathogen detection rate.