Virulence Reversion in Staphylococcus aureus

Staphylococcus aureus is a Gram-positive opportunistic pathogen that imposes heavy burden on society. What sets this apart the sheer spectrum of infections it can cause, which range from benign skin and soft tissue to lethal endocarditis bacteraemia. The ability S. cause gamut conferred by its arsenal virulence factors are under control Accessory Gene Regulator (Agr) system. However, large proportion clinical isolates have inactivating mutations in important regulatory We previously showed that, contrary common dogma, not all these evolutionary ‘dead-ends’ fraction phase variants revert an Agr active state. Here we report some deficient haemolytic phenotype without repairing their collected series 30 negative primary patient samples order assess significance our previous findings existence variants. used avoid strains had undergone multiple clonal expansions before being tested for reversibility. assessed reversibility serially passaging screening phenotypic reversion haemolysis. show two reverted haemolysis one alpha haemolysin activity any genetic changes agr (and hla revertant). These results add further complexity phenomenon shutdown observed setting corroborate recent compensatory arising strains.