Molecular and epidemiologic predictors of Staphylococcus aureus colonization site in a population with limited nosocomial exposure

Background: The anterior naris has been considered the most consistent location of asymptomatic Staphylococcus aureus colonization. However, recent studies have shown that a substantial number of individuals, ranging from 7% to 32% of colonized individuals, are exclusive throat carriers. Most of these studies have been carried out in a health care setting, limiting their generalizability to nonhospitalized populations. Methods: To evaluate anatomic carriage sites of S aureus in individuals outside of a health care setting, we combined the results of 2 cross-sectional studies conducted in Iowa. Results: S aureus was carried by 103 of 340 individuals (30.3%), including 31 (30.1%) exclusive throat carriers, 44 (42.7%) exclusive nose carriers, and 28 (27.2%) colonized in both sites. Nonwhite race (adjusted odds ratio [OR], 4.91; 95% confidence interval [CI], 1.26-18.3) and younger age (>= 30 years: OR, 0.23; 95% CI, 0.10-0.54) were associated with increased odds of exclusive throat carriage, whereas nonwhite race (OR, 5.14; 95% CI, 1.62-16.3) and spring or summer sampling season (OR, 2.62; 95% CI, 1.32-5.18) were associated with increased odds of exclusive nasal carriage. Conclusions: These findings suggest that including a throat swab in addition to a nasal swab could play an important role in the success of surveillance programs, particularly among younger adults. Copyright (C) 2012 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.