Haemophilus ducreyi hemolysin acts as a contact cytotoxin and damages human foreskin fibroblasts in cell culture.

Haemophilus ducreyi, which causes the sexually transmitted disease chancroid, produces several factors that damage human cells. We used isogenic mutants of H. ducreyi 35000 to demonstrate that the hemolytic activity and the cytotoxic effect of H. ducreyi on human foreskin fibroblasts are due to the same toxin.