Prevalence of<i>Staphylococcus aureus</i>Nasal Colonization in the United States, 2001–2002

TLDR

Staphylococcus aureus commonly causes disease, especially in colonized individuals, yet population‑based colonization estimates were previously unavailable. The study analyzed nasal swabs from 9,622 adults and children in the 2001–2002 NHANES, testing isolates for methicillin resistance, antimicrobial susceptibility, clonal type, toxin genes, and SCCmec elements. Nationally, 32.4 % of U.S.

Abstract

Staphylococcus aureus is a common cause of disease, particularly in colonized persons. Although methicillin-resistant S. aureus (MRSA) infection has become increasingly reported, population-based S. aureus and MRSA colonization estimates are lacking.Nasal samples for S. aureus culture and sociodemographic data were obtained from 9622 persons > or = 1 year old as part of the National Health and Nutrition Examination Survey, 2001-2002. After screening for oxacillin susceptibility, MRSA and selected methicillin-susceptible S. aureus isolates were tested for antimicrobial susceptibility, pulsed-field gel electrophoresis clonal type, toxin genes (e.g., for Panton-Valentine leukocidin [PVL]), and staphylococcal cassette chromosome mec (SCCmec) type I-IV genes.For 2001-2002, national S. aureus and MRSA colonization prevalence estimates were 32.4% (95% confidence interval [CI], 30.7%-34.1%) and 0.8% (95% CI, 0.4%-1.4%), respectively, and population estimates were 89.4 million persons (95% CI, 84.8-94.1 million persons) and 2.3 million persons (95% CI, 1.2-3.8 million persons), respectively. S. aureus colonization prevalence was highest in participants 6-11 years old. MRSA colonization was associated with age > or = 60 years and being female but not with recent health-care exposure. In unweighted analyses, the SCCmec type IV gene was more frequent in isolates from participants of younger age and of non-Hispanic black race/ethnicity; the PVL gene was present in 9 (2.4%) of 372 of isolates tested.Many persons in the United States are colonized with S. aureus; prevalence rates differ demographically. MRSA colonization prevalence, although low nationally in 2001-2002, may vary with demographic and organism characteristics.