Staphylococcus aureus colonization before elective posterior spine surgery: is it associated with postoperative S. aureus infections?

OBJECTIVE: Evidence suggests that preoperative Staphylococcus aureus colonization predicts postoperative superficial surgical site infection (SSI). However, it is unclear how preoperative colonization is related to deep surgical site, organ space, and bloodstream infections after spine surgery. Therefore, the objective of this study was to investigate associations between preoperative S. aureus colonization and S. aureus infections following elective, instrumented posterior spine surgery. METHODS: The authors retrospectively analyzed international trial data from 3311 participants who underwent open, instrumented, multilevel posterior spine surgery from 2015 to 2019. Multivariate logistic regression was used to determine associations between preoperative S. aureus colonization and postoperative S. aureus infection. RESULTS: Thirty-five percent of participants (n = 1148) had preoperative S. aureus colonization in the nose or throat. Within 3 months after surgery, 68 of all participants (2%) developed S. aureus infections. Preoperative colonization was associated with greater odds of superficial SSI (OR 1.7, 95% CI 1.2-2.3; p = 0.004) and bloodstream infection (OR 1.8, 95% CI 1.1-4.2; p = 0.017). Other factors associated with postoperative infection included nasal (relative to throat) colonization (OR 1.03, 95% CI 1.01-1.1; p = 0.038), number of vertebrae fused (OR 1.2, 95% CI 1.1-1.2; p < 0.001), and BMI (OR 1.1, 95% CI 1.03-1.1; p < 0.001). Prophylactic decolonization was associated with lower odds of infection (OR 0.6, 95% CI 0.42-0.84; p = 0.003). Specifically, the odds were lower for participants treated with chlorhexidine wash (OR 0.4, 95% CI 0.25-0.64; p < 0.001), intranasal mupirocin (OR 0.13, 95% CI 0.02-0.98; p = 0.048), or both (OR 0.56, 95% CI 0.33-0.98; p = 0.041). CONCLUSIONS: Preoperative S. aureus colonization was associated with superficial SSI and bloodstream S. aureus infections after elective spine surgery. Prophylactic decolonization measures were associated with lower odds of postoperative infection. Future analysis should explore optimal decolonization regimens for at-risk individuals.