Haemophilus ducreyi: pathogenesis and protective immunity.

Haemophilus ducreyi is the etiological agent of chancroid, a sexually transmitted disease that is common in developing countries and that has characteristic genital mucocutaneous lesions. The adherence and growth of bacteria on the surface of eukaryotic cells, and the production of cytotoxin(s) result in cell damage that may be responsible for the development of ulcers. The mechanisms for protective immunity in chancroid are unclear, but both humoral and cell-mediated mechanisms may be involved.