Chancroid

After an incubation of three to seven days a tender papule becomes a pustule and then a sharply demarcated ulcer with undermined, ragged borders and a purulent, easily bleeding base; unlike the syphilitic chancre it is not indurated, hence 'soft chancre'. Multiple ulcers are common through autoinoculation on apposed surfaces, the so-called kissing lesions. Painful, often unilateral inguinal buboes may become fluctuant and rupture. Chancroid substantially increases HIV transmission risk by breaching the epithelial barrier, so HIV and syphilis testing are mandatory, and syphilis serology should be repeated because early infection may be seronegative. Diagnosis is usually clinical, since culture is insensitive and PCR is not widely available; the CDC definition requires typical ulcers, no evidence of Treponema pallidum on darkfield or serology at least seven days after onset, typical adenopathy, and a negative herpes test. Treatment is single-dose azithromycin or ceftriaxone, and sexual partners from the preceding ten days should be treated.