An Aspirin A Day Keeps Staphylococcus Aureus Away

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An Aspirin A Day Keeps Staphylococcus Aureus Away

(Journal of Clinical Investigation) -- In the July 15 issue of The

Journal of Clinical Investigation, Ambrose Cheung and colleagues at

Dartmouth School of Medicine in New Hampshire, USA, report that

salicylic acid (SAL), the major metabolite of aspirin, downregulates two

Staphylococcus aureus genes key to this organism's pathogenesis.

Over 100 years have passed since S. aureus was first described as the

organism responsible for causing sepsis and abscesses. Today it remains

a leading cause of serious infections such as endocarditis, pneumonia,

and septicemia and requires intensive antibiotic therapy, which is often

unsuccessful due to the rise of antibiotic resistant strains. Aspirin

has previously been shown to reduce the virulence of S. aureus in models

of endocarditis. In an earlier study, this same group found that while

administration of aspirin or its metabolite, SAL, was capable of

reducing the ability of S. aureus to attach to host cells, the effect

was significantly enhanced following SAL administration.

In this issue of the JCI, Cheung and colleagues extend these earlier

findings and report that treatment with SAL induced activation of the S.

aureus stress response gene sigB, resulting in downregulation of

regulons sarA and agr, which control the expression of the genes

encoding a-hemolysin and fibronectin. This downregulation resulted in

decreased ability of the bacteria to adhere to host cells, and reduced

S. aureus toxin-mediated hemolysis and thrombolysis of host cells.

" The establishing of a straightforward, unequivocal strategy to

downregulate staphylococcal virulence using a cheap, simple, relatively

non-toxic, resorbable compound such as SAL may be seen as major progress

in the development of intervening strategies in addition to

antimicrobial drugs " stated Professor Mathias Herrmann, Director of the

Department of Bacteriology and Hygiene at the University of Saarland,

Germany in his accompanying commentary. The report is the first

description of aspirin-mediated genetic effects against S. aureus and

represents an exciting new prospect for this widely used and established

drug.