Natural history of Staphylococcus aureus nasal carriage and its relationship to exit-site infection

To study the natural history of nasal carriage of Staphylococcus aureus (SA) and its impact on exit-site infection (ESI).

A teaching hospital single-center study.

A prospective cohort study in prevalent continuous ambulatory peritoneal dialysis (CAPD) patients.

153 patients (76 male, 77 female; mean age 46 years) with a mean duration of CAPD of 2.4 years.

Nasal swabs were taken at approximately 2-month intervals over the mean period of follow-up of 22.6 months and cultured for SA.

An average of 69% of patients received systemic antibiotics for therapy of ESI, peritonitis, and other infections during the period of the study, but none received local nasal antibiotics. Four groups of patients were identified according to their nasal carriage history: chronic, intermittent, occasional, and noncarriers. The intermittent and chronic carriers had significantly higher SA ESI than the occasional and noncarrier groups. The intermittent group also had the highest percentage of non-SA ES infections.

Although this study shows that only half of our CAPD patients with nasal carriage were at risk of developing ESI, we recommend that patients with a positive nasal swab at the start of CAPD therapy should be treated with nasal antibiotics or local antibiotics at the exit site.