Patients with rheumatoid arthritis (RA) being treated with disease-modifying anti-rheumatic drugs (DMARDs) and biologics have a significantly increased risk for Staphylococcus aureus nasal colonization; therefore, decolonization protocols are advisable for patients in this population who are undergoing joint replacement surgery to decrease the risk for surgical infections, according to a study published in The Journal of Arthroplasty.
The aim of this study was to determine S aureus nasal carriage rates for patients with RA on biologic therapy, patients with RA on traditional DMARDs, and osteoarthritis. To detect a relative difference of 20% among groups with 80% power, 369 participants (mean age 66, 78% women) were enrolled from April 2017 to May 2018 in 3 equal groups of 123 based on an a priori power analysis. Participants answered questions to identify risk factors and administered their own nasal swab with sterile cotton swabs. Spa typing was used to further categorize S aureus positive swabs. After controlling for known risk factors, the association with S aureus nasal colonization between groups was evaluated using logistic regression. All statistical analysis was done using SAS software version 9.3.
RA patients on biologics had a 37% rate of S aureus colonization. Of the patients with RA, 70% (n=86) who were being treated with biologics were also on DMARDs. These participants had statistically significant increases in the rate of S aureus colonization compared with participants with RA on DMARDs only, or osteoarthritis (35%, 24%, and 20%, respectively; P =.01). After controlling for antibiotic use, diabetes, glucocorticoids, and recent hospitalization, participants with RA on biologics had a significantly increased risk of S aureus nasal colonization (odds ratio, 1.80; 95% CI, 1.00-3.22; P =.047).
Limitations include only utilizing nasal swabs, patient administered swabs, small group sizes, and other observational study-related risk factors.
Study investigators conclude, “Because nasal S aureus carriage may play a role in the pathogenesis of surgical infections, our results help explain the increase in surgical infections in RA patients on TNFis, and support the use of decolonization protocols in order to potentially decrease the increased risk of [periprosthetic joint infection] seen in patients with RA undergoing joint replacement surgery.”
One or more authors declare a conflict of interest. Please refer to the reference for a full list of authors’ disclosures.
Goodman SM, Nocon AA, Selemon NA, et al. Increased Staphylococcus aureus nasal carriage rates in rheumatoid arthritis patients on biologic therapy [published online January 17, 2019]. J Arthroplasty. doi:10.1016/j.arth.2019.01.025