HAEMOPHILUS-DUCREYI ADHERES TO BUT DOES NOT INVADE CULTURED HUMAN FORESKIN CELLS

Haemophilus ducreyi is the etiologic agent of the localized genital ul cer disease known as chancroid. The pathogenesis of this organism is p oorly understood. The role of attachment in the disease process has no t been evaluated. In this study, I-125-H. ducreyi was used to quantita tively evaluate the interaction of virulent and avirulent H. ducreyi s trains with human foreskin cells. Using this in vitro model system, we demonstrated that, at 22 and 35-degrees-C, the attachment of virulent H. ducreyi 35000 to human foreskin cells was significantly more marke d than that of avirulent H. ducreyi A77. Although H. ducreyi penetrate d between human foreskin cells, internalization was not a major compon ent. Our competition assay data suggest that the attachment mechanism of H. ducreyi may be similar to that of Neisseria gonorrhoeae. We spec ulate that the attachment and microcolony formation of virulent H. duc reyi may provide a mechanism for bacterial localization and evasion of host defenses.