Changes in the Prevalence of Nasal Colonization with Staphylococcus aureus in the United States, 2001–2004

BackgroundStaphylococcus aureus is a common cause of infection, particularly in persons colonized by this organism. Virulent strains of methicillin-resistant S. aureus (MRSA) have emerged in the general community MethodsA nationally representative survey of nasal colonization with S. aureus was conducted from 2001 through 2004 as part of the National Health and Nutrition Examination Survey. MRSA isolates were identified by the oxacillin disk-diffusion method. The pulsed-field gel electrophoresis (PFGE) type was determined for all MRSA isolates. A t statistic was used to compare the prevalence of colonization across biennia and across population subgroups. Cofactors independently associated with colonization were determined with backward stepwise logistic modeling ResultsThe prevalence of colonization with S. aureus decreased from 32.4% in 2001–2002 to 28.6% in 2003–2004 (P