Inhibition of virulence of Staphylococcus aureus - a food borne pathogen - by squalene, a functional lipid

Increased resistance of Staphylococcus aureus - a pathogen responsible for hospital and food related infections - to several antibiotics has become a major concern. Staphyloxanthin, a carotenoid, is attributed to be the major virulent factor contributing to the pathogenicity of S. aureus. The present study investigated squalene for its ability to render S. aureus avirulent and consequent effect on staphyloxanthin. Squalene inhibited staphyloxanthin synthesis in S. aureus as confirmed by spectral profiling and HPLC analysis. It also reduced the haemolytic ability of the pathogen in a dose dependent manner (0.05-0.75 mM). Squalene pre-treatment increased the susceptibility of the pathogen to oxidants by 48% and reduced the neutrophil resistance by about 82%. Further, biofilm forming ability of S. aureus was also affected by squalene. This is the first evidence of the antivirulent effects of squalene, a functional lipid, and, provides an alternate approach for treating S. aureus infections.