Isolation of Haemophilus ducreyi from genital ulcerations in white men in Johannesburg.

An analysis of sexually acquired genital ulcerations in 31 White patients who were examined microbiologically in Johannesburg showed Haemophilus ducreyi to be the causative agent in 23 (74%), whereas syphilis was the confirmed diagnosis in only 6 (19%). All the H. ducreyi isolates produced beta-lactamase. Previously, chancroid was considered to be an infrequent cause of genital ulceration in this population group. Unlike those with syphilitic ulceration, patients with chancroid usually do not respond to penicillin. The improved isolation procedures for H. ducreyi now enable the laboratory to confirm most cases.