FIG 3.

Hemolysis of red blood cells. Hemolysis of rabbit erythrocytes was measured spectrophotometrically and compared with lysed erythrocyte standards to calculate percent hemolysis. The tests were performed by using each SCV strain (gray bars), the SCV strains grown in media supplemented with 1 μg/ml menadione (black bars), and the SCV strains with wild-type men genes (white bars). LAC was included as a wild-type positive control; S. epidermidis does not produce alpha-toxin (negative control). A single asterisk indicates a significant difference in red blood cell hemolysis between the menadione-supplemented strain and the matching SCV strain. A double asterisk indicates a significant difference in percent hemolysis between the complemented or revertant strain and the corresponding SCV strain (P < 0.05 by t test). Data are the means ± standard deviations of at least 3 independent experiments.