Longitudinal Case Series of Staphylococcus aureus Colonization and Infection in Two Cohorts of Rural Iowans.

OBJECTIVE: Examine the relationship between colonization with Staphylococcus aureus in the community and symptomatic infection in two cohorts of Iowans.

DESIGN: Case series within cohort study.

PARTICIPANTS: Rural Iowans selected from the Keokuk Rural Health Study, the Agricultural Health Study, and the Iowa Voter Registry.

METHODS: Longitudinal study within established cohorts evaluating documented S. aureus infections with samples available for molecular typing.

RESULTS: We examined this relationship in two cohorts of Iowans with a combined 11 incident cases of S. aureus SSTI, for which samples were available. Seven of the 11 individuals (63.6%) were colonized at baseline, in the nose (3/7, 42.9%), or in both the nose and throat (57.1%). All seven cases had matching sequence types between colonization and infection isolates.

CONCLUSIONS: Staphylococcus aureus causes millions of skin and soft tissue infections yearly. Although colonization with S. aureus is a frequent antecedent to infection, many studies investigating the link between colonization and infection have taken place in a clinical setting, particularly in urban hospitals. Our study has shown similar results in a rural community setting to those previously seen in clinics.