**8.3 Diagnosis**

Definitive diagnosis of chancroid requires cultivation of *H. ducreyi* on special culture media, which is not routinely carried in most laboratories. Culture on two media is recommended as not all *H. ducreyi* strains can be cultured using one medium. Culture also requires a humid environment, 5% CO2, and incubation at 33-35 oC. Swabs for culture are collected from the undermined edge of the ulcer and the fastidious nature of *H. ducreyi* necessitates use of transport media if the organisms are not cultured within a few hours. Presumptive diagnosis by microscopy is possible if the organism load in ulcers is high and Gram-negative coccobacillus arranged in chains, paired chains or aggregates ("school of fish" appearance) are visualized. However the value of microscopy for diagnosis is limited by low sensitivity and specificity of this technique. Aspirates from buboes are less likely to yield positive results on microscopy or culture. In many cases chancroid is diagnosed clinically and treated without a definitive diagnosis. The combination of painful genital ulcer and suppurative inguinal lymphadenopathy is also supportive of a diagnosis of chancroid. Nucleic acid amplification tests for diagnosis have been developed but are not widely available.

#### **8.4 Treatment**

Azithromycin (1 g orally) or ceftriaxone (250 mg IM) offer the advantage of single-dose therapy. Alternatively ciprofloxacin (500 mg orally twice daily for 3 days) or erythromycin base (500 mg orally three times a day for 7 days) may be used. For reasons of cost, erythromycin is usually used for treatment in developing countries. Isolates with intermediate resistance to ciprofloxacin or erythromycin have been reported but data are rather limited on the current status of *H. ducreyi* drug resistance. Ulcerative lesions should be kept clean to avoid the chance of secondary infections. Fluctuant lymph nodes can be aspirated through healthy skin. Incision and drainage or excision of nodes may delay healing. Uncircumcised men and HIV-positive patients may not respond as well to treatment. Large ulcers may require weeks to resolve after treatment and patients should be followed until there is clear evidence of improvement or cure.
