Lack of correlation between nasal cultures positive for Staphylococcus aureus and the development of S. aureus exit-site infections: results unaffected by routine mupirocin treatment of nasal S. aureus carriage.

Whether nasal carriage of Staphylococcus aureus is associated with an increased risk of S. aureus exit-site infection remains controversial. We performed nasal cultures prior to peritoneal dialysis catheter placement in all of our patients beginning in September 1990. We also performed nasal cultures on a cohort of patients already on peritoneal dialysis. Patients with positive cultures received a prescription for a ten-day course of intranasal mupirocin. Exit-site and nasal cultures were performed on every subsequent office visit until the end of the study in April 1993. The initial visit and three widely-spaced subsequent visits were chosen for data analysis. There were 68 patients entered into the study. Data from a total of 272 visits were analyzed. The patients ranged in age from 18-80 years. There were 27 diabetics. We found no correlation between initial positive nasal cultures and the subsequent development of a S. aureus exit-site infection. All identified nasal carriers were treated with mupirocin. However, the subsequent development of a S. aureus exit-site infection could not be correlated to a prior S. aureus carrier state or lack thereof.