The Impact of Vancomycin and Cefazolin as Standard Preoperative Antibiotic Prophylaxis on Surgical Site Infections Following Instrumented Spinal Fusion

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To assess whether administration of prophylactic vancomycin, in addition to cefazolin decreased revision surgeries for postoperative infection (SSI) as well as the need for revisions overall. SUMMARY OF BACKGROUND DATA: In 2010 our institution implemented an antibiotic prophylaxis regimen consisting of intravenous vancomycin and cefazolin that applied to all patients receiving surgical implants. The impact of this change in prophylactic antibiotic regimen on SSIs following instrumented spinal fusions remains unknown. METHODS: We conducted a prepost analysis evaluating the effect of the change in antibiotic prophylaxis on SSIs following instrumented spinal fusions. We collected data on all eligible patients over the course of 2005 to 2009 and 2011 to 2015. We used logistic regression techniques to evaluate unadjusted results for the prophylactic antibiotic protocol on all revision surgeries, as well as those for SSI, followed by sequential adjustments for sociodemographic factors and surgical characteristics. RESULTS: Revision surgeries performed for a diagnosis of infection were reduced from a rate of 4% (n = 57) in the period 2005 to 2009 to 2% (n = 44) over 2011 to 2015 (P < 0.001). At the same time, the incidence of revision surgeries for any cause was also reduced (14% in 2005-2009 vs. 9% in 2011-2015; P < 0.001). In adjusted analysis, the odds of a revision procedure for SSI were reduced by 50% following introduction of the protocol (OR 0.50; 95% CI 0.33, 0.76). No significant difference in the organisms responsible for SSI was identified between 2005 and 2009 and 2011 and 2015 (P = 0.22). CONCLUSION: This natural experiment has shown some utility for a preoperative prophylactic antibiotic regimen of vancomycin and cefazolin, including meaningful reductions in revision procedures performed for SSI. This is the first effort we are aware of to consider a uniform institutional protocol that employs the use of intravenous vancomycin and cefazolin as prophylactic agents. LEVEL OF EVIDENCE: 2.