Haemophilus ducreyi (PCR)

Swab of skin or mucous membrane lesion

Haemophilus ducreyi is an aerobic, gram-negative, coccoid, immobile rod-shaped bacterium which is transmitted through unprotected sexual contact.
They penetrate tissues through skin and mucous membrane lesions and are the causative agent of ulcus molle (soft chancre). Infections mainly occur in tropical and subtropical climates. In these regions, Haemophilus ducreyi is one of the most important pathogens of genital ulcerations.
Soft ulcers first appear on the genitals 3 to 5 days after infection, followed by painful swelling and abscessation of the lymph nodes in the inguinal region after weeks. Extragenital ulcers are rare, disseminated infections are not known.

Diagnosis by PCR is the standard method, cultivation is difficult.