Staphylococci: Colonizers and Pathogens of Human Skin

Rosanna Coates; Josephine Moran; Malcolm J Horsburgh

Disclosures

Future Microbiol. 2014;9(1):75-91. 

In This Article

Colonization & Persistence: The Role of Adhesins

A primary requirement for colonizing the skin surface is adherence to the flattened, cornified keratinocytes. Microbial adhesins specific for receptors on the skin minimize loss by mediating strong attachments to prevent detachment by sheer forces and ensuring reattachment before desquamation. It is unknown whether adhesion to the uppermost surface of the skin is sufficient for long-term skin survival or whether penetration and adhesion to deeper layers of the skin is necessary (Figure 1). Purported methods for sampling different layers of the skin include skin swab (topmost layer), skin scrape (upper layers) or skin punch biopsy (all skin layers). Zeeuwen et al. recently proposed that bacteria found at a depth of several cell layers represent the indigenous microbiome rather than those of superficial skin layers.[2] Their study used a tape-stripping method to remove superficial skin layers prior to taking swabs of the area, then 16S rDNA sequencing was performed to compare the microbiota with an area without tape-stripping. However, this method does not account for skin surface irregularities, which may result in parts of the superficial layers not being removed, while in an adjacent area, potentially removing many more layers at the same time, resulting in swabs not necessarily sampling equivalent layers. By contrast, Grice et al. reported that skin swab, scrape and punch samples shared 97.2% of operational taxonomic units, revealing few differences in the microbiome between skin depths.[24]

There is good evidence that adhesins contribute differentially during distinct stages of S. aureus nasal epithelium colonization. The nonproteinaceous adhesin wall teichoic acid is important during initial colonization,[25–28] (revealed by the inability of wall teichoic acid biosynthesis mutants to colonize[28]), whereas the microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) IsdA and ClfB were more important for colonization and persistence.[25,26] It is not known if equivalent adhesins are important for skin colonization across the staphylococci.

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