Clinical characteristics and risk factors of blood stream infections after orthopedic surgery

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To analyze the clinical characteristics, risk factors, and drug resistance of pathogenic bacteria in patients with blood stream infections (BSI) after orthopedic surgery, so as to provide reference and basis for clinical diagnosis and treatment. A retrospective analysis was made on the clinical data of 6 348 orthopedic patients admitted for surgery between January 2017 and December 2019. There were 3 598 males and 2 750 females. Their age ranged from 18 to 98 years, with an average of 66 years. The data of patients were collected, and the risk factors of BSI were analyzed by univariate analysis and logistic regression analysis. The distribution of BSI pathogenic bacteria, the results of drug sensitivity test, the incidence of BSI in patients after orthopedic surgery in different years, and the common sites of BSI secondary infection were summarized. BSI occurred in 106 (1.67%) of 6 348 patients after orthopedic surgery. There were 71 cases (66.98%) of secondary infection. The mortality of postoperative BSI patients was 1.89%, and the difference was significant when compared with that of non-postoperative BSI patients (0.24%) ( χ 2=5.313, P=0.021). The incidences of BSI in 2017, 2018, and 2019 were 1.18%, 1.53%, and 2.17%, respectively, showing an increasing trend year by year (trend χ 2=6.610, P=0.037). Statistical analysis showed that the independent risk factors for BSI after orthopedic surgery ( P<0.05) included the trauma, length of hospital stay≥14 days, emergency surgery, postoperative leukocyte counting<4×10 9/L, level of hemoglobin≤90 g/L, albumin≤30 g/L, the time of indwelling ureter>24 hours, use of deep vein catheter insertion, and merging other site infection. Blood culture showed 56 strains (52.83%) of Gram-positive bacteria, 47 strains (44.34%) of Gram-negative bacteria, and 3 strains (2.83%) of fungi. The top three pathogenic bacteria were coagulase negative Staphylococci (CNS; 36 strains, 33.96%), Escherichia coli (16 strains, 15.09%), and Staphylococcus aureus (15 strains, 14.15%). The detection rates of extended-spectum β-lactamases producing strains of Escherichia coli and Klebsiella pneumoniae were 56.25% (9/16) and 44.44% (4/9), respectively. The detection rates of methicillin-resistant strains in Staphylococcus aureus and CNS were 46.67% (7/15) and 72.22% (26/36), respectively. Postoperative BSI in orthopedic patients is caused by multiple factors. Preventive measures should be taken according to related risk factors and perioperative risk assessment should be strengthened. Staphylococcus and Escherichia coli are the most common pathogenic bacteria in BSI after orthopedic surgery. The infection rate and drug-resistant bacteria are increasing year by year. Therefore, drug resistance monitoring should be strengthened.