Phenol-soluble modulin

Phenol-soluble modulins (PSM) are a family of protein toxins that are soluble in phenols, that are produced by CA-MRSA, and which are thought to be a possible cause of severe infections.

PSM toxins are encoded by the genome meaning, unlike virulence genes encoded on mobile genetic elements, all species of Staphylococcus carry these genes. Although PSM toxins are produced in all methicillin-resistant Staphylococcus aureus strains, the more virulent CA-MRSA strains are typically associated with higher production. Genetic analysis demonstrated that the PSM-alpha protein, product of the psm-alpha gene cluster, was associated with enhanced virulence and enhanced destruction of white blood cells, presumably the key to the higher infectivity. However, expression of the psm-alpha genes appeared to vary, dependent upon unknown factors specific to each particular infection.

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