Haemophilus ducreyi

Gram Stain

• Gram negative bacilli small pleomorphic (facultative anaerobic)

Clinical Significance

This organism is the cause of chancroid, an ulcerative painful genital ulcer associated with inguinal lymphadenopathy. Incubation is 2-7 days after exposure.

Usual Susceptibility Pattern

This organism is usually resistant to amoxicillin, tetracyclines, and TMP/SMX.

It is susceptible to 3rd generation cephalosporins, macrolides, and quinolones.