Chancroid

This sexually-transmitted illness begins as a tender, reddened papule filled with pus. It then breaks down, ulcerates and reveals a grayish, necrotic base with jagged, irregular margins.

There is no significant induration around the base, unlike primary syphilis. In untreated cases, the lesions may spread and substantial tissue damage may result. Tender, enlarged inguinal lymph nodes are found in 50% of patients.

Hemophilus ducreyi, the causative organism, is difficult to culture, so the diagnosis is made on the basis of history, physical exam and exclusion of other ulcerative diseases of the vulva. A gram-stain from the base of a clean ulcer or aspirate from a bubo may reveal a gram-negative coccobacillus clustered in groups around polymorphonucleocytes ("school of fish " appearance).

Good choices for treatment include any of the following:

• Azithromycin 1 g orally in a single dose,
• Ceftriaxone 250 mg intramuscularly (IM) in a single dose,
• Ciprofloxacin 500 mg orally twice a day for 3 days,
• Erythromycin base 500 mg orally four times a day for 7 days.

CDC Treatment Guidelines