Effect of fatty acids on Staphylococcus aureus delta-toxin hemolytic activity

The lysis of human erythrocytes by Staphylococcus aureus delta-toxin proceeded without a lag and was directly proportional to toxin concentration and temperature of incubation. Lysis was complete within 8 min. Addition of saturated, straight-chain fatty acids of 13 to 19 carbons increased the activity of delta-toxin, whereas those with 21 to 23 carbons were inhibitory. Palmitic acid was the fatty acid most active in augmenting delta-toxin, but its effect could be abolished by the simultaneous addition of either tricosanoic acid or egg lecithin.