Alcohol increases hemolysis by staphylococci

It was recently found that alcohols can confer hemolytic properties on certain species of yeast. Here, it is reported that alcohol can promote hemolysis by various species of staphylococci, including strains of Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus hominis. In order to study this novel phenomenon in S. aureus and S. epidermidis, strains that exhibit this phenomenon (e.g. S. aureus 8325-4, COL, SH1000, S. epidermidis), as compared with strains that exhibited little alcohol-enhanced hemolysis (e.g. S. aureus 8325-4 DeltaTRAP, RN6911) were examined. Both ethanol and n-butanol caused upregulation of the virulence regulator-RNAIII, with a concomitant increase in the production of alpha, beta and gamma-hemolysins in strain 8325-4. In S. aureus COL and SH1000, there was an increase in RNAIII but no change in transcription levels of alpha, beta and gamma hemolysins. Staphylococcus epidermidis stain sofi exhibited increased RNAIII and beta hemolysin production. Staphylococcus aureus mutant strains (8325-4 DeltaTRAP and RN6911) showed no change in the transcription level of the RNAIII regulator and the above hemolysins. Increased hemolysis in S. aureus COL, SH1000 and mutant strains may be caused by other hemolysins (not regulated by RNAIII) or through other mechanisms such as hyperoxidation or cytotoxic lipids.