Intrawound application of vancomycin changes the responsible germ in elective spine surgery without significant effect on the rate of infection: a randomized prospective study

B. Mirzashahi, M. Chehrassan, S. M. J. Mortazavi

Surgical site infection (SSI) is a costly complication associated with spine surgery. The impact of intrawound vancomycin has not been strongly postulated to decrease the risk of surgical site infection. We designed study to determine whether intrawound vancomycin application reduces the risk of SSI in patients after spine surgery. A prospective randomized control trial study to evaluate the patients with elective spine surgery in a period of 15 month was designed. Patients were divided into two groups based on whether intrawound vancomycin was applied or not. The relative risk of SSI within postoperative 30 days was evaluated. Three hundred and eighty patients were included in this study: degenerative spine pathologies and tumor 80% (304), trauma 11% (42) and deformity 9% (34). Intrawound vancomycin was used in 51% of patients. Prevalence of SSI was 2.7% in the absence of vancomycin use versus 5.2% with intrawound vancomycin. In multivariable regression model, those with higher number of levels exposed, postoperative ICU admission and obesity and use of instrumentation more than two levels had higher risk of developing SSI. In the treatment group Acinetobacter and Pseudomonas aeruginosa (20%) were the most common pathogens. In control group, Staphylococcus aureus and Acinetobacter (40%) were the most common organisms. Intrawound application of vancomycin after elective spine surgery was not associated with reduced risk of SSI and return to OR associated with SSI in our patients. However, the use of intrawound vancomycin changed the responsible infection germ.