Etiology and Epedimiology

Chancroid is caused by Haemophilus ducreyi, a fastidious gram-negative bacillus. It is prevalent in many developing countries but occurs sporadically in the developed world. Most Western cases occur in returning travelers (90% are male) from endemic areas, and some occur occasionally in localized urban outbreaks associated with commercial sex workers. This disease is a risk factor for transmission of HIV. Diagnosis of chancroid in infants and children is strong evidence of sexual abuse. Male circumcision lowers the risk for chancroid.

Clinical Manifestations

The incubation period is 4-7 days with a small inflammatory papule on the preputial orifice or frenulum in men and on the labia, fourchette, or perineal region in women. The lesion becomes pustular, eroded, and ulcerative within 2-3 days. The ulcer edge is classically ragged and undermined. Without treatment, the ulcers may persist for weeks to months. Painful, tender inguinal lymphadenitis occurs in > 50% of cases, more often among men. The lymphadenopathy can become fluctuant to form buboes, which can spontaneously rupture.

Diagnosis

Diagnosis of chancroid is usually established by the clinical presentation and the exclusion of both syphilis (Treponema pallidum) and herpes simplex virus infection. Gram stain preparation of ulcer secretions may show gram-negative coccobacilli in parallel clusters (“school of fish”). Culture requires expensive, special media and has a sensitivity of only 80%. Polymerase chain reaction analysis and indirect immunofluorescence using monoclonal antibodies remain research tools but may become the best means of diagnosis. The ulcer of chancroid is accompanied by concurrent lymphadenopathy that is usually unilateral, unlike lymphogranuloma venereum (Chapter 218.4). Genital herpes is characterized by vesicular lesions with a history of recurrence (Chapter 244).

Treatment

Most clinical isolates of H. ducreyi are resistant to penicillin and ampicillin because of plasmid-mediated β-lactamase production. Spread of plasmid-mediated resistance among H. ducreyi has resulted in lack of efficacy of previously useful drugs such as sulfonamides and tetracyclines. Chancroid is highly responsive to treatment. The current treatment recommendation is for azithromycin (1 g as a single dose PO) or ceftriaxone (250 mg as a single dose IM). Alternative regimens include erythromycin (500 mg tid PO for 7 days), which is most often used in developing countries, and ciprofloxacin (500 mg bid PO for 3 days, for persons ≥ 18 yr of age). Fluctuant nodes may require drainage. Symptoms usually resolve within 3-7 days. Relapses can usually be treated successfully with the original treatment regimen. Patients with HIV infection may require longer duration of treatment. Persistence of the ulcer and the organism following therapy should raise suspicion of resistance to the prescribed antibiotic.

Patients with chancroid should be evaluated for other sexually transmitted infections because an estimated 10% have concomitant syphilis or genital herpes. In developing countries, patients with a compatible genital ulcer are treated for both chancroid and syphilis. All sexual contacts of patients with chancroid should be evaluated and treated.

Complications

Complications of chancroid include phimosis in men and secondary bacterial infection. Bubo formation may occur in untreated cases. Genital ulceration increases the risk for transmission of HIV.