Background:

Preoperative methicillin-resistant Staphylococcus aureus (MRSA) testing and decolonization has demonstrated success for arthroplasty patients in surgical site infections (SSIs) prevention. Spine surgery, however, has seen varied results.

Purpose:

The purpose of this study was to determine the impact of nasal MRSA testing and operative debridement rates on surgical site infection after primary lumbar fusion.

Study design/setting:

Retrospective cohort study/Consolidated medical enterprise PATIENT SAMPLE: Adult patients undergoing primary instrumented lumbar fusions from January 2015-December 2019 were reviewed.

Outcome measures:

The primary outcome was incision and drainage performed in the operating room within 90 days of surgery.

Methods:

MRSA testing <90-days before surgery, mupirocin prescription <30-days before surgery, perioperative antibiotics, and Elixhauser comorbidity index were collected for each subject. Bivariate analysis used Wilcoxon rank-sum testing and logistic regression modeling Multivariable logistic regression modeling assessed for associations with MRSA testing, intravenous vancomycin use, and I&D rate.

Results:

The study included 1,884 patients for analysis, with mean age of 63.1 (SE 0.3) and BMI 29.5 (SE 0.1). MRSA testing was performed in 755 patients (40.1%) and was more likely to be performed in patients with lower Elixhauser index scores (OR 0.98, 95% CI 0.96-0.99, p=0.021) on multivariable analysis. Vancomycin use increased significantly over time (OR 1.49/year, 95% CI 1.3-1.8, p<0.001) despite no change in mupirocin or I&D rates. MRSA testing, mupirocin prescriptions, perioperative parenteral vancomycin use, and intrawound vancomycin powder use had no impact on I&D rates. I&D risk was associated with higher BMI (OR 1.06, 95% CI 1.02-1.12, p=0.009) and higher number of blood product units transfused (OR 1.23, 95% CI 1.03-1.46, p=0.022).

Conclusions:

The present study demonstrates no impact on surgical I&D rates from the use of preoperative MRSA testing. Increased BMI and transfusions were associated with operative I&D rates for surgical site infection. As a result of the hospital directive, vancomycin use increased over time with no associated change in infection rates, underscoring the need for focused interventions and engagement with antibiotic stewardship programs.