Risk Factors for Staphylococcus aureus Nasal Colonization in Joint Arthroplasty Patients

Background: Several studies have shown that Staphylococcus aureus (S aureus) nasal colonization is associated with surgical site infection and that preoperative decolonization can reduce infection rates. Up to 30% of joint arthroplasty patients have positive S aureus nasal swabs. Patient risk factors for colonization remain largely unknown. The aim of this study was to determine whether there is a specific patient population at increased risk of S aureus nasal colonization. Methods: This study is a retrospective review of 716 patients undergoing hip or knee arthroplasty beginning in 2011. All patients were screened preoperatively for nasal colonization. Univariate and multivariate analyses were used to assess risk factors for nasal colonization. Results: A total of 716 patients undergoing joint arthroplasty had preoperative nasal screening. One hundred twenty-five (17.50%) nasal swabs were positive for methicillin-susceptible S aureus (MSSA), 13 (1.80%) were positive for methicillin-resistant S aureus (MRSA), and 84 (11.70%) were positive for other organisms. In bivariate analysis, diabetes (P =.04), renal insufficiency (P =.03), and immunosuppression (P =.02) were predictors of nasal colonization with MSSA/MRSA. In multivariate analysis, immunosuppression (P =.04; odds ratio, 2.0; 95% confidence interval, 1.03-3.71) and renal insufficiency (P =.04; odds ratio, 2.5; 95% confidence interval, 1.01-6.18) were independent predictors of nasal colonization with MSSA/MRSA. Conclusion: Overall, 17.5% of patients undergoing primary hip or knee arthroplasty screened positive for S aureus. Diabetes, renal insufficiency, and immunosuppression are risk factors for such colonization. Given that these comorbidities are already known independent risk factors for periprosthetic joint infection, these patients should be particularly screened and when necessary, decolonized.