Predictors of S aureus Nasal Colonization in TJA Patients

Data from a study to be presented today indicate that diabetes, renal insufficiency, and immunosuppression are risk factors for Staphylococcus aureus (S aureus) nasal colonization in total joint arthroplasty (TJA) patients.

“Our study sought to determine if there is a specific patient population at increased risk of S aureus nasal colonization,” coauthor Calin S. Moucha, MD, said. “Through a retrospective chart review of 716 patients undergoing TJA at our institution, we found that the common comorbidities of diabetes, renal insufficiency, and immunosuppression are predictors of nasal colonization with S aureus. It is important to note that in some series these comorbidities also have an established association with higher rates of periprosthetic joint infection and other postoperative adverse outcomes.”

Dr. Moucha added, “Preoperative S aureus screening has not been universally adopted despite significant evidence that establishes S aureus nasal colonization is associated with surgical site infection and that preoperative decolonization can reduce infection rates. The results of our study may encourage arthroplasty surgeons who do not currently perform preoperative nasal colonization testing to at the very least screen patients who are at higher risk for colonization and thus postoperative infection.”

The study, “Risk Factors for Staphylococcus Aureus Nasal Colonization in Joint Replacement Patients,” will be presented today at 10:54 a.m. in room W315. The following is the study’s abstract:

Introduction: Several studies have shown that Staphylococcus aureus (S aureus) nasal colonization is associated with postoperative surgical site infection and that preoperative decolonization can reduce infection rates. Up to 30 percent of joint replacement patients have positive S aureus nasal swabs, and patient risk factors for colonization remain largely unknown. Many joint replacement patients continue to undergo surgery without being screened. The aim of this study was to determine if there is a specific patient population at increased risk of S aureus nasal colonization.

Methods: This study is a retrospective review of 716 consecutive patients undergoing hip or knee replacement surgery beginning in 2011. All patients were screened preoperatively for nasal colonization, and patients who screened positive for S aureus were treated with mupirocin. Univariate and multivariate statistical analyses were used to assess risk factors for nasal colonization.

Results: Overall, 125 (17.5%) nasal swabs were positive for methicillin susceptible S aureus (MSSA), 13 (1.8%) were positive for methicillin resistant S aureus (MRSA), 84 (11.7%) were positive for other organisms, and 494 (69%) were negative for colonization. In bivariate analysis, diabetes (P = 0.04), renal insufficiency (P = 0.03), and immunosuppression (P = 0.02) were predictors of nasal colonization with MSSA/MRSA, while smoking (P = 0.02) and immunosuppression (P = 0.001) were predictors of colonization with other bacteria.

In multivariate analysis, immunosuppression (P = 0.04, odds ratio (OR): 2.0, 95% confidence interval (CI): 1.03–3.71), and renal insufficiency (P = 0.04, OR: 2.5, 95% CI: 1.01–6.18) were independent predictors of nasal colonization with MSSA/MRSA, while smoking (P = 0.02, OR: 1.8, 95% CI: 1.10–2.88) and immunosuppression (P = 0.01, OR: 3.0, 95% CI: 1.45–5.86) were independent predictors of nasal colonization with other bacteria.

Discussion and Conclusion: Almost 20 percent of patients undergoing primary hip or knee replacement surgery 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 in particular should be screened and when necessary, decolonized.         

Dr. Moucha’s coauthors are Amanda Walsh, MD; Adam C. Fields, BA; James D. Dieterich, BA; Christine Carbonaro, PA-C; Dena L. McDonough, PA-C; Maureen Walsh, PA-C; Darwin D. Chen, MD; and Michael J. Bronson, MD.

Details of the authors’ disclosures as submitted to the Orthopaedic Disclosure Program can be found in the Final Program; the most current disclosure information may be accessed electronically at www.aaos.org/disclosure

Advertisements

Advertisement