Comparison of Surgical Site Infection After Instrumented Spine Surgery in Patients With High Risk of Infection According to Different Antibiotic Prophylaxis Protocols: A Cohort Study of 132 Patients With a Minimum Follow-Up of 1 year.

Study design: Observational Study.

Objectives: Surgical site infections (SSIs) are one of the major complications in spine surgery. Numerous factors that increase the risk of SSI have been widely described. However, clinical guidelines on antibiotic prophylaxis are usually common for all patients. There are no specific guidelines for patients with a high risk of infection. The aim of this paper is to create a specific protocol for patients at high risk of SSI.

Methods: This is a three-cohort study using a prospective database. Risk patients are those who meet at least two of the following criteria: obesity, diabetes, reoperation and immunosuppression. Between October 2021 and April 2023, 132 patients were recruited.They were divided into three cohorts: cohort A, 46 patients, standard prophylaxis with cefazolin 2 g/8 h for 24 h; cohort B, 46 patients, cefazolin 2 g/8h and amikacin 500 mg/12 h for 24 h; cohort C, 40 patients, cefazolin 2 g/8h and amikacin 500 mg/12 h for 72 h.

Results: There was a significant decrease in the infection rate depending on the prophylaxis (23.9% in cohort A, 8.7% in cohort B, and 2.5% in cohort C). When logistic regression models were applied and cohorts B and C were compared with A, the following results were obtained: OR of 0.30 (CI: 0.08 - 0.97; P = 0.057) and 0.08 (IC: 0.00 - 0.45; P = 0.019), respectively.

Conclusions: Prophylaxis with prolonged double antibiotic therapy with cefazolin and amikacin is associated with a statistically significant decrease in the rate of SSI in patients with a high risk of infection.