Which bacterium causes chancroid?

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sexually transmitted disease Scanning electron micrograph of the spirochete *Treponema pallidum* attached to testicular cell membranes.

Chancroid is an acute, localized sexually transmitted disease caused by the bacterium Haemophilus ducreyi.12

This microorganism typically produces painful, shallow ulcers in the genital area within three to five days of exposure. Unlike syphilis, which can present with a hard chancre, the lesions associated with chancroid are often referred to as soft chancres. The condition is treated with antibiotics.12