INCREASED RISK OF SURGICAL SITE INFECTION AFTER SPINE SURGERY WITH VANCOMYCIN SURGICAL ANTIBIOTIC PROPHYLAXIS WHEN COMPARED TO CEFAZOLIN

Surgical site infection (SSI) after spine surgery has severe negative health and financial consequences. Surgical antibiotic prophylaxis (SAP) is a routinely used method to prevent SSIs in the spine patient population. The most commonly used antibiotic is cefazolin, with vancomycin often being substituted in the case of penicillin or cephalosporin allergy. Vancomycin as SAP has been associated with increased SSI in the joint replacement literature, but this is not yet well defined in the spinal surgery population. The purpose of this study is to determine whether vancomycin SAP compared to cefazolin SAP is associated with increased risk of SSI. A retrospective analysis was conducted on previously gathered data from a single-center randomized controlled trial on 552 patients, aged 16 years or older who underwent elective, multi-level open posterior spinal fusion surgery at the thoracic, thoracolumbar, or lumbar levels. Demographic and operative characteristics as well as post-operative outcomes were compared between the following groups: 1) noninfected-cefazolin, 2) noninfected-vancomycin, 3) infected-cefazolin, and 4) infected-vancomycin. The primary outcome measures were superficial and complicated (deep and organ/space) infections. Risk factors were then identified with statistical analysis using multivariate logistic regression. The following risk factors for SSI were identified in a logistic regression analysis: vancomycin (OR 2.498, 95% CI, 1.085–5.73, p=0.031), increasing operating time (OR 1.006, 95% CI, 1.001–1.010 p=0.010), weight (OR 1.020, 95% CI 1.006–1.034, p=0.005), revision procedure (OR 2.343, 95% CI 1.283–4.277, p=0.006), and depression (OR 2.366, 95% CI 1.284–4.360, p=0.006). In open posterior approach spinal fusion surgery, vancomycin SAP is associated with increased risk of infection compared to cefazolin SAP, and this increased risk is not necessarily a result of inadequate dose or timing of administration. Clinicians should ensure patients with a suspected beta-lactam allergy receive appropriate pre-operative investigation into the nature of their allergy in order to prevent unnecessary administration of vancomycin in those who can ultimately tolerate cefazolin.