Abstract: Objective To explore bacterial distribution and their relationship with serum procalcitonin (PCT), C-reactive protein (CRP), soluble myeloid cells trigger receptor-1 (sTREM-1) and soluble cluster of differentiation antigen 14 (sCD14) in patients with infection after fracture internal fixation. Method A total of 88 patients with infection and 88 patients without infection after fracture internal fixation in Nanjing Tongren Hospital Affiliated to Southeast University School of Medicine were retrospectively enrolled as infection group and control group between March 2021 and March 2024, respectively. The distribution of postoperative infection pathogens was statistically analyzed. The inflammatory indexes were compared among patients with different pathogens and between infection group and control group, and their diagnostic value in postoperative infection was analyzed. The risk factors of postoperative infection in patients with fracture internal fixation were analyzed by univariate and multivariate regression analysis. Result In the 88 patients with postoperative infection, including Gram-negative bacteria [53.41%, mainly on Escherichia coli (25.00%)] and Gram-positive bacteria [46.59%, mainly on Staphylococcus aureus (23.86%)]. Among the 88 patients with postoperative infection, there were 47 cases with Gram-negative bacteria infection (Gram-negative bacteria group) and 41 cases with Gram-positive bacteria infection (Gram-positive bacteria group). The levels of PCT, CRP, sTREM-1 and sCD14 in Gram-negative bacteria group were higher than those in Gram-positive bacteria group (P<0.05). Compared with control group, levels of PCT, CRP, sTREM-1 and sCD14 were higher in infection group (all P<0.05). The results of ROC curves analysis showed that AUC of PCT combined with CRP, sTREM-1 and sCD14 in the diagnosis of postoperative infection was 0.956, greater than that of single index (P<0.05). Univariate analysis showed that there were significant differences in incision type, invasive operation, diabetes mellitus, hypoproteinemia, postoperative use time of antibiotics, PCT, CRP, sTREM-1 and sCD14 between the two groups (P<0.05). Multivariate Logistic regression analysis showed that diabetes mellitus, hypoproteinemia, postoperative antibiotics use time >15d, PCT >101.13mg/L, CRP >72.61mg/L, sTREM-1 >190.37mg/ml and sCD14 >2.13μg/ml were all independent risk factors of postoperative infection in patients with fracture internal fixation (P<0.05). Conclusion The levels of serum PCT, CRP, sTREM-1 and sCD14 are increased in patients with infection after fracture internal fixation, and the incease of inflammatory factors in patients with Gram-negative bacteria infection is more significant than those with Gram-positive bacteria infection. The combined detection of serum PCT, CRP, sTREM-1 and sCD14 has higher diagnostic value in infection after fracture internal fixation.

Key words: Fracture internal fixation, Serum procalcitonin, C-reactive protein, Soluble myeloid cell trigger receptor-1, Soluble cluster of differentiation antigen 14, Postoperative infection