Hemolytic action of staphylococcal alpha-hemolysin on human erythrocytes in a Na plus-and K plus-containing suspending fluid

Alpha-Toxin Contributes to Biofilm Formation among Staphylococcus aureus Wound Isolates

Biofilms complicate treatment of Staphylococcus aureus (SA) wound infections. Previously, we determined alpha-toxin (AT)-promoted SA biofilm formation on mucosal tissue. Therefore, we evaluated SA wound isolates for AT production and biofilm formation on epithelium and assessed the role of AT in biofilm formation. Thirty-eight wound isolates were molecularly typed by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (ST), and spa typing. We measured biofilm formation of these SA isolates in vitro and ex vivo and quantified ex vivo AT production. We also investigated the effect of an anti-AT monoclonal antibody (MEDI4893*) on ex vivo biofilm formation by methicillin-resistant SA (USA 300 LAC) and tested whether purified AT rescued the biofilm defect of hla mutant SA strains. The predominant PFGE/ST combinations were USA100/ST5 (50%) and USA300/ST8 (33%) for methicillin-resistant SA (MRSA, n = 18), and USA200/ST30 (20%) for methicillin-susceptible SA (MSSA, n = 20). Ex vivo AT production correlated significantly with ex vivo SA wound isolate biofilm formation. Anti-alpha-toxin monoclonal antibody (MEDI4893*) prevented ex vivo biofilm formation by MRSA USA300 strain LAC. Wild-type AT rescued the ex vivo biofilm defect of non-AT producing SA strains. These findings provide evidence that AT plays a role in SA biofilm formation on epithelial surfaces and suggest that neutralization of AT may be useful in preventing and treating SA infections.

Effect of staphylococcal alpha-hemolysin upon anion transport in the rabbit erythrocyte

Equilibrium exchange of SO4(2-) was measured prior to and during hemolysis in rabbit erythrocytes exposed to staphylococcal alpha-hemolysin. The anion-transport protein of the rabbit erythrocyte has also been identified. Equilibrium exchange of SO4(2-) was measured by both efflux and influx of 35SO4(2-). The rate of influx of SO4(2-) in rabbit erythrocytes exposed to alpha-hemolysin was twice that of the untreated cells. The rate of SO4(2-) efflux was unchanged by alpha-hemolysin. Inhibition of anion exchange with 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS) did not inhibit hemolysis, therefore, the increased influx of SO4(2-) may occur through a DIDS-insensitive pathway.