EXPERIMENTAL HUMAN INFECTION WITH HAEMOPHILUS-DUCREYI

Four subjects were experimentally infected with Haemophilus ducreyi. L esions developed only at sites where live bacteria were inoculated on abraded skin. No subject developed fever, lymphadenopathy, or dissemin ated infection during a 3-day observation period. Two subjects who wer e rechallenged 2 months after initial infection also developed lesions . The amount of H. ducreyi recovered from 10 of 12 biopsies that were semiquantitatively cultured varied widely. Similar histologic features were present in initial and second infections. The epidermis containe d pustules; the dermis contained an infiltrate of T cells and macropha ges and reactive endothelial cells. Keratinocytes and T cells expresse d HLA-DR, consistent with a delayed-type hypersensitivity response. Th e subjects did not mount humoral responses to bacterial proteins and t o lipooligosaccharides after primary and secondary challenges. Thus, h uman experimental infection with H. ducreyi is well tolerated and safe . Recruitment of T cells and macrophages into chancroid lesions may pa rtially explain the association between chancroid and human immunodefi ciency virus transmission.