In 1889, Auguste Ducrey at the University of Naples published his research about the causing agent of chancroid (ulcus molle or chancre mou) associated with the presence of genital ulcers, Haemophilus ducreyi, which is a gram-negative bacillus, was named after the scientist.  Chancroid is a sexually transmitted disease (STD), very often found in HIV sufferers, and the etiologic agent in chronic skin ulcers in the South Pacific region.
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haemophilus ducreyi

Image: “Haemophilus ducreyi bacteria – the causative agent of chancroid, stained with Gentian Violet.” Obtained from the CDC Public Health Image Library. License: Public Domain

Definition and Background of Haemophilus Ducreyi

Being a fastidious facultative anaerobic, gram-negative, non-spore-forming coccobacillus, H. ducreyi grows best in a humid atmosphere containing 5% CO2, at the temperature of 34-35°C (microaerophilic conditions).

The infection is usually localized in the genital area. There are some cases of extragenital infection caused by H. ducreyi on the inner thighs, breast and fingers. The causing factor can trigger the development of the infectious disease in humans only.

Etiology of Haemophilus Ducreyi

H. ducreyi is transmitted sexually if there is a direct contact with open lesions and exudate. It mainly affects the genital area. The incubation period is 4 – 7 days.

On the place of the bacterial invasion, there are tender papules after sexual intercourse (on the prepuce, frenulum, glans or anus in men and on the vulva, cervix and perianal area in women), later they turn into putulae, which rupture after 2 – 3 days forming uneven ulcers. If the ulcers are not treated timely, they may heal longer than usually (up to 3 months).

Also, there may be some complications when secondary (opportunistic) infection entering the place of the lesion leading to the occurrence of phimosis in men, phagedenic ulceration due to secondary bacterial infection, and unilateral lymphadenopathy (50% of cases).

A long-time tetracycline and trimethoprim-sulfamethoxazole (TMP-SMX) treatment of genital ulcers led to the emergence of the widespread resistant strain of H. ducreyi in developing countries.

Epidemiology of Haemophilus Ducreyi

United States

In 2000 – 2014, studies reported almost no cases of H. ducreyi in the US, as well as in Southeast Asia and the Caribbean. In 2013, only 10 cases were reported in different states. Age prevalence is 20-24-year-old males and females. Chancroid is the third most common cause in the United States.


The main reason of chronic skin ulceration (60%) in Papua New Guinea, Solomon International Islands, Vanuatu, and Ghana is reported to be H. ducreyi. Botswana, Mozambique, South Africa, Uganda, Pakistan and France were marked by less than 10% of all cases of ulcerative lesion of the skin and genitals. There is a racial predominance; non-white men who are uncircumcised are usually affected most of all.

Presentation of Haemophilus Ducreyi


H. ducreyi is a devoted companion of immune compromised conditions; usually, this ailment is diagnosed in HIV patients; especially those who practice promiscuity in sexual contacts and homosexual men. The patients with H. ducreyi ulcers may reveal that they had unprotected sex with prostitutes. Other signs may be:

  • Dyspareunia
  • Vaginal discharge
  • Fever
  • Weakness
  • Papules, pustules, anogenital ulcers (bubo) and surrounding areas
  • Painful local (inguinal) lymphadenitis, lymphatic nodes can rupture themselves.

Physical examination

Erythematous papules form 3 – 7 days after the contact with an infected person, usually on the prepuce or frenulum in males and on the vulva, cervix or perianal region in females. Later, they transform into pustules and the last stage is the ulceration of the affected skin. The ulcers are with irregular borders, there are a possible ring of erythema, purulent exudate and granulomatous bases there.

Differential Diagnosis of Haemophilus Ducreyi

  • Herpes simplex
  • Syphilis (chancre)
  • Psoriasis
  • Trauma
  • Behçet syndrome
  • Fixed drug eruptions

Diagnosis of Haemophilus Ducreyi

Laboratory studies

  • Polymerase chain reaction (PCR): almost 100% specific and sensitive but expensive.
  • Microscopy of Gram stain smear: H. ducreyi looks like “fingerprints” or “schools of fish.”
  • Immunochromatography: 100% specific but cost-effective. It takes 15 minutes to perform the test, useful in express diagnostics of painful genital ulcers.


  • Papular staging
  • Pustular staging
  • Ulcerative staging

Management of Haemophilus Ducreyi


  • Azithromycin
  • Ciprofloxacin
  • Erythromycin (7 days) is the first-line treatment for chancroid, as it is not contraindicated for pregnant women and children, unlike ciprofloxacin.

Short courses of these antibiotics in the accordance of the age and weight are efficiently administered in the treatment of chancroid.

HIV patients tend to have longer healing ulcers; that’s why Erythromycin 500mg qds for 7 days is the treatment of choice.

Buboes may be treated with administration of needle aspiration and/or incision and drainage.



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