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Staphylococcus aureus in Patients with Rheumatoid Arthritis Under Conventional and Anti-Tumor Necrosis Factor-a Treatment
STEFANO BASSETTI, SARAH WASMER, PAUL HASLER, THOMAS VOGT, DANICA NOGARTH, RENO FREI, and ANDREAS F. WIDMER
ABSTRACT.
Objective. To compare the prevalence of nasal and oral Staphylococcus aureus in patients with rheumatoid arthritis (RA) with the prevalence in controls with other rheumatic diseases, and to determine predictors of S. aureus carriage and the influence of treatment with anti-tumor necrosis factor-a (anti-TNF-a) agents. Methods. Eighty-one patients with RA and 83 other control patients of 2 outpatient rheumatology clinics were cultured for nasal and oral carriage of S. aureus. Quantitative nasal cultures for S. aureus were performed from swabs of the anterior nares, the posterior pharynx, and the soft palate. Information on medications, medical conditions, and risk factors for S. aureus carriage was collected from all participants by a questionnaire and confirmed by chart review. Results. The S. aureus carriage rate (nasal and/or oral colonization) was 34.6% among RA patients and 32.5% among controls (p = 0.87). Being treated with an anti-TNF-a agent plus methotrexate (MTX) was the only independent predictor of S. aureus carriage (OR 3.24, 95% CI 1.16–9.05, p = 0.025). The S. aureus carriage rate among RA patients treated with an anti-TNF-a agent plus MTX was 60% (9/15) versus 23.1% (3/13) in RA patients treated with an anti-TNF-a agent only (p = 0.049). All S. aureus isolates were susceptible to oxacillin. Conclusion. The S. aureus carriage rate among patients with RA was not higher than among controls. Treatment with anti-TNF-a agents was not associated with an increased S. aureus carriage rate. However, treatment with an anti-TNF-a agent plus MTX may predispose patients to S. aureus carriage. (J Rheumatol 2005;32:2125-9) Key Indexing Terms:
STAPHYLOCOCCUS AUREUS From the Division of Infectious Diseases and Hospital Epidemiology, Microbiology Laboratory, University Hospital Basel, Basel; University Department of Rheumatology, Felix Platter-Spital, Basel; and Department of Rheumatology, Kantonsspital Aarau, Aarau, Switzerland. Dr. Bassetti was supported by grants from the University of Basel (Sonderprogramm zur Förderung des akademischen Nachwuchses) and from the Department of Internal Medicine (VFWAWF), University Hospital Basel, Basel, Switzerland. S. Bassetti, MD, Assistant Professor of Medicine, University of Basel, Senior Registrar; S. Wasmer, Med Pract, Resident, Division of Infectious Diseases and Hospital Epidemiology, University Hospital Basel; P. Hasler, MD, Professor of Medicine, University of Basel, Head of Rheumatology, Kantonsspital Aarau; T. Vogt, MD, Staff Physician, University Department of Rheumatology, Felix Platter-Spital; D. Nogarth, Laboratory Technician, Division of Infectious Diseases and Hospital Epidemiology, and Microbiology Laboratory, University Hospital Basel; R. Frei, MD, Head of Microbiology, University Hospital Basel; A.F. Widmer, MD, MS, Professor of Medicine, University of Basel, Head of Hospital Epidemiology, University Hospital Basel. Address reprint requests to Dr. S. Bassetti, Division of Infectious Diseases and Hospital Epidemiology, University Hospital Basel, CH-4031 Basel, Switzerland. E-mail: sbassetti@uhbs.ch Accepted for publication June 3, 2005. |