Virulence and antibiotic susceptibility of Staphylococcus aureus strains isolated from various origins.

We looked for links between the antibiotic susceptibility pattern of Staphylococcus aureus strains, their source and their virulence genes. Forty-four methicillin-sensitive and -resistant S. aureus strains from four antibiogroups were studied by SmaI macrorestriction and PCR detection of ea, eb, tst, lukS-PV and lukF-PV. Genes encoding virulence factors were most prevalent (i) in S. aureus strains originated from skin, (ii) in methicillin-sensitive, quinolone-resistant strains or in methicillin-sensitive multiresistant strains (EMSSA strains), and (iii) in strains with decreased susceptibility or resistance to fusidic acid. This is consistent with the hypothesis that S. aureus antibiotic resistance promoted by local antibiotic treatment also contributes to the emergence of virulence strains.