Educational Attainment and Staphylococcus aureus Colonization in a Hispanic Border Community: Testing Fundamental Cause Theory

This study was carried out to evaluate hypotheses generated by fundamental cause theory regarding the socioeconomic status (SES) gradient in colonization with Staphylococcus aureus among Hispanic and non-Hispanic adults living in a border community. Participants (n = 613) recruited in naturally occurring small groups at public and private sites throughout Yuma County, AZ, completed a sociodemographic survey and swabbed their palms, noses, and throats to sample microbial flora. Positive S. aureus colonization among non-Hispanic white participants was nominally higher (39.0%; 95% confidence interval [CI] = 32.4 to 46.1%) than that in Hispanics (31.3%; 95% CI = 26.4 to 36.8%), but there was no education gradient for the sample overall (incidence rate ratio = 1.00; 95% CI = 0.90 to 1.12) or within each ethnic group separately. The education gradient between Hispanic and nonHispanic whites was statistically equivalent. Results were consistent when home ownership was used as the SES indicator. These data show that S. aureus colonization is not linked to two different SES indicators or Hispanic ethnicity. S. aureus colonization may be considered a less preventable health risk that is outside the influence of SES-based resources. IMPORTANCE Unlike some types of S. aureus infections, S. aureus colonization is not associated with ethnicity or educational attainment and thus may be outside the influence of socioeconomic status-based resources typically mobilized to avoid or mitigate preventable health risks. This assessment of a clinically silent risk that usually precedes infections may illustrate a boundary of fundamental cause theory.