THE EFFECT OF INTRAWOUND VANCOMYCIN POWDER ON SURGICAL SITE INFECTIONS IN POSTERIOR INSTRUMENTED SPINAL ARTHRODESES

Abstract

Summary: We reviewed 371 consecutive patients from Oct. 2008 to Sept. 2011 who underwent posterior instrumented spinal arthrodesis and received intrawound vancomycin powder prior to closure and compared their acute, deep infection rate to 371 consecutive patients from Oct. 2008 to Apr. 2005 who underwent posterior spinal instrumented arthrodesis and did not receive intrawound vancomycin. We found the use of vancomycin powder decreased the acute, deep Staphylococcus infection rate from 2.05% to 0 (p=0.008). Vancomycin powder is an effective way to decrease acute, deep S. aureus infections following spine surgery. Introduction: Surgical site infection is a serious complication for patients undergoing instrumented spinal surgery. Staphylococcus aureus is the most common causative agent associated with post-op wound infections. Recent studies have reported a decreased infection rate with intrawound vancomycin use in spine surgeries. We sought to determine if intrawound vancomycin would decrease the rates of acute, deep S. aureus infections in our posterior instrumented spinal arthrodesis patients. Methods: This is a historical cohort study. All procedures were performed by a single surgeon. 371 consecutive patients undergoing posterior instrumented spinal arthrodesis received intrawound vancomycin in addition to standard antimicrobial prophylaxis beginning in Oct. 2008 through Sept. 2011 (Vanco cohort). We compared them to 371 consecutive patients from Oct. 2008 to Apr. 2005 who did not receive intrawound vancomyin (Historical cohort). We excluded any superficial infection (above the lumbosacral fascia) or any infection occurring after 90 days. Infection rates were analyzed with Fisher exact test. Results: We found 8 (2.4%) acute, deep infections in the Historical cohort: 1 Enterococcus and 7 (2.05%) Staphylococcus (6 of which were S. aureus). We found 4 (1.2%) acute, deep infections in the Vanco group, none of which were S. aureus. There were 2 E.coli, 1 Klebsiella oxytoca, and 1 anaerobic Streptococcus. The difference in total acute, deep infection rate between the Historical cohort and Vanco cohort was not significant (p= 0.262), but the decrease in Staphylococcus infection rate in the Vanco group was significant (p=0.008). Conclusion: Intrawound vancomycin powder has decreased the rate of acute, deep Staphylococcus infections in our posterior instrumented spinal fusion patient population from 2.05% to 0. Our Vanco cohort was significantly older but otherwise similar in terms of risk factors to the Historical cohort, though had fewer infections. This work is adding to the growing body of evidence in support of this effective adjuvant to standard antimicrobial prophylaxis.