Why the bacterium S.Aureus just gets up your nose?

In a new study, researchers from the School of Biochemistry and Immunology and the Department of Microbiology at Trinity College Dublin have shown that a protein located on the bacterial surface called clumping factor B (ClfB) has high affinity for the skin protein loricrin.

Staphylococcus aureus (S. Aureus) is a major human pathogen, with the potential to cause severe invasive diseases.

It is a major cause for concern in hospitals and healthcare facilities, where many infections are caused by strains resistant to commonly used antibiotics [MRSA], the study said.

The bacterium S. Aureus persistently colonises about 20 per cent of the human population by binding to skin-like cells within the nasal cavity.

Being colonised predisposes an individual towards becoming infected so it is vital that we understand the mechanisms involved. ClfB was previously shown to promote S. Aureus colonisation in a human nasal colonisation volunteer study.

The study, published in the Open Access journal PLOS Pathogens, identifies the mechanism by which ClfB facilitates S. Aureus nasal colonisation.

Purified ClfB bound loricrin with high affinity and this interaction was shown to be crucial for successful colonization of the nose in a mouse model.

It showed that soluble loricrin could reduce binding of S. aureus to human nasal skin cells and that nasal administration of loricrin reduced S. Aureus colonization of mice.

Rachel McLoughlin, the study's corresponding author and Lecturer at the School of Biochemistry and Immunology at Trinity College Dublin concludes, "Loricrin is a major determinant of S. Aureus nasal colonization."

This discovery opens new avenues for developing therapeutic strategies to reduce the burden of nasal carriage and consequently infections with this bacterium.