STUDY DESIGN: Case-control study.OBJECTIVES: To analyze the microbial flora in surgical spine infections and their antibiotic resistance patterns across time and determine the correlation between vancomycin application in the wound and vancomycin-resistant microbes.SUMMARY OF BACKGROUND DATA: Prior studies show a reduction in surgical site infections with intrawound vancomycin placement. No data are available on the potential negative effects of this intervention, in particular, whether there would be a resultant increase in vancomycin-resistant organisms or bacterial resistance profiles.METHODS: All culture-positive surgical site infections at a single institution were analyzed from 2007 to 2017. Each bacterium was assessed independently for resistance patterns. The two-tailed Fisher exact test was used to determine the correlation between vancomycin application and the presence of vancomycin-resistant bacteria, polymicrobial infections, or gram-negative bacterial infections.RESULTS: One hundred and eight bacteria were isolated from 113 surgical site infections from 2007 to 2017. The most common organisms were staphylococcus with varying resistance patterns and Escherichia coli. Vancomycin-resistant Enterococcus faecium was isolated in three infections. Out of the 4,878 surgical cases from 2011 to 2017, vancomycin was placed in 48.3%, and no vancomycin in 51.7%. There were 33 infections (1.4%) in the vancomycin group and 20 infections (0.8%) in the no-vancomycin group (chi2 = 0.0521). There was no correlation between vancomycin application in the wound and vancomycin-resistant microbes (chi2 = 0.2334) and polymicrobial infections (chi2 = 0.1328). There was an increased rate of gram-negative organisms in infections after vancomycin application in the wound versus no vancomycin (chi2 = 0.0254).CONCLUSIONS: Topical vancomycin within the surgical site is not correlated with vancomycin-resistant bacteria. However, there was an increased incidence of gram-negative organisms in infections after vancomycin application in the wound versus no vancomycin. Continued surveillance with prospectively collected randomized data is necessary to better understand bacterial evolution against current antimicrobial techniques.LEVEL OF EVIDENCE: Level III.
View details for DOI 10.1016/j.jspd.2019.01.005
View details for PubMedID 31495468