Staphylococcus aureus nasal colonization and colonization or infection at other body sites in patients on a burn trauma unit

Abstract

Objective: To determine whether Staphylococcus aureus isolates from the nares of patients on a burn trauma unit were related to isolates colonizing or infecting other body sites.

Design: Active surveillance for S. aureus, a case-control study, and pulsed-field gel electrophoresis of S. aureus isolates.

Setting: A burn trauma unit of a Midwestern university teaching hospital.

Patients: Patients admitted from February 1, 2002, through March 30, 2007, who had S. aureus isolated either from a nasal culture and from another body site (case patients) or from a nasal culture alone (control subjects).

Results: Nineteen patients met the case patient definition and had paired isolates from the nares and an additional site available for typing. Of the 19 case patients, 8 had infections, 7 of which were caused by methicillin-resistant S. aureus (5 USA100 strain and 2 USA300 strain). A total length of stay of more than 3 weeks (odds ratio [OR], 8.75 [95% confidence interval {CI}, 2.2-34.6]; P = .002), residence in a long-term care facility (OR, 9.4 [95% CI, 2.1-42.5]; P = .004), and diabetes (OR, 3.2 [95% CI, 1.0-10.0]; P = .05) were associated with the isolation of S. aureus from the nares and other sites. Seventeen case patients (89.5%) had closely related isolates obtained from culture of samples from the nares and from other sites.

Conclusions: Prolonged length of stay, diabetes, or residing in a long-term care facility increased the risk of having S. aureus at sites other than the nares. S. aureus isolates from other body sites usually were closely related to nasal isolates. Most case patients had colonized or infected wounds that could be a source of S. aureus for other patients.