Nasal Carriage ofStaphylococcus aureus

Abstract

The study conducted by von Eiff and colleagues (Jan. 4 issue)¹ might give readers the impression that a bacterial nose swab was merely a blind sample from the vestibulum nasi. The authors do not provide a precise description of the method used to obtain bacterial swabs from the nose. A colleague and I found that the bacterial spectrum differs considerably between the vestibulum nasi and the cavitas nasi; for example, Staphylococcus aureus was present in the cavitas nasi but not in the vestibulum nasi in 22 percent of 412 patients (P=0.001).² This finding indicates that disinfection of the vestibule alone may not prevent colonization of the nasal cavity by S. aureus. The fact that the bacterial populations differ is not surprising, because the linings of the vestibule and cavity differ and constitute dissimilar microenvironments. There is also evidence of a genetically determined affinity between the nasal mucosa cells and certain bacteria such as S. aureus. ³ From our experience, nasal swabs should always be obtained through a nasal speculum with the help of a head mirror so as to obtain representative microbial samples from both the vestibule and the cavity.