Haemophilus ducreyi: Chancroid

Haemophilus ducreyi is a small, Gram-negative coccobacillus that causes the genital ulcer disease known as chancroid. Chancroid increases the risk for transmission and acquisition of HIV-1. The prevalence of the disease is unknown due to syndromic management of genital ulcer disease, but outbreaks continue to be reported in developing countries and in populations with high numbers of sexual partners. Patients with chancroid seek medical care several weeks after acquiring the infection when they become symptomatic and complain of painful genital ulcers that are often associated with suppurative inguinal lymphadenopathy. Research has focused on identifying virulence factors, the most notable of which play roles in adherence to extracellular matrix components and resistance to both phagocytosis and complement-mediated killing. Single-dose antibiotic therapy with macrolides or third-generation cephalosporins or with fluoroquinolones remains effective for the treatment of chancroid, but patients remain susceptible to reinfection as protective immunity does not develop.