Staph: It's deeper than you think

For decades it's been known that the primary site of staphylococcal colonization is the anterior nares. Now there is a new, interesting paper in the Journal of Hospital Infection that provides a better understanding of colonization. Nasal swabs were performed on 37 cadavers and 9 were found to have colonization with S. aureus. The noses were then surgically removed and tissue sections taken. An antibody stain against S. aureus was applied to visualize the site of colonization. There were two important findings: (1) colonization only occurred distally in the stratified squamous epithelium (i.e., there was no colonization of the more proximal ciliated mucosa; and (2) in 6/9 cadavers, staph organisms were visualized in the hair follicle shaft, and in 2 the bacteria were visualized deep in the follicle. The presence of S. aureus deep in the hair follicle may explain why some patients do not decolonize or recolonize after decolonization with mupirocin since the drug may not be able to penetrate that deeply.