<unk>  is a fastidious gram-negative coccobacillus bacteria. It causes the sexually transmitted disease chancroid, a major cause of genital ulceration in developing countries characterized by painful sores on the genitalia. Chancroid starts as an erythematous papular lesion that breaks down into a painful bleeding ulcer with a necrotic base and ragged edge. More recently, it has also been found to cause chronic skin ulceration away from the genitalia, infect children and adults, and behave in a manner that mimics yaws. These strains seem to have diverged quite recently.<unk>  can be cultured on chocolate agar. It is best treated with a macrolide, e.g. azithromycin, and a third-generation cephalosporin, e.g. ceftriaxone.<unk>  gram stain resembles a "school of fish."
Haemophilus ducreyi
Mycoplasma genitalium
Trichomonas tenax
Chlamydia trachomatis
Mycobacterium ulcerans
Veillonella parvula
Treponema pallidum
Coxa vara