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Classification and external resources
Chancroid lesion haemophilus ducreyi PHIL 3728 lores.jpg
A chancroid lesion on penis
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Classification and external resources
Chancroid lesion haemophilus ducreyi PHIL 3728 lores.jpg
A chancroid lesion on penis

Chancroid (also known as soft chancre[1] and ulcus molle[2]) is a bacterial sexually transmitted infection characterized by painful sores on the genitalia. Chancroid is known to spread from one individual to another solely through sexual contact.


Chancroid is a bacterial infection caused by the fastidious Gram-negative streptobacillus Haemophilus ducreyi. It is a disease found primarily in developing countries, most prevalent in low socioeconomic groups, associated with commercial sex workers. In the United States socioeconomic status has not been found to be a factor in the spread of sexually transmitted diseases. [3]

Chancroid, caused by H. ducreyi has infrequently been associated with cases of Genital Ulcer Disease in the US, but has been isolated in up to 10% of genital ulcers diagnosed from STD clinics in Memphis and Chicago.

Infection levels are very low in the Western world, typically around one case per two million of the population (Canada, France, Australia, UK and US).[citation needed] Most individuals diagnosed with chancroid have visited countries or areas where the disease is known to occur frequently, although outbreaks have been observed in association with crack cocaine use and prostitution.[citation needed]

Chancroid is a risk factor for contracting HIV, due to their ecological association or shared risk of exposure, and biologically facilitated transmission of one infection by the other.


H. ducreyi enters skin through microabrasions incurred during sexual intercourse. A local tissue reaction leads to development of erythomatous papule, which progresses to pustule in 4–7 days. It then undergoes central necrosis to ulcerate.[4]

Signs and symptoms[edit]

Buboes in a male

These are only local and no systemic manifestations are present.[5] The ulcer characteristically:

About half of infected men have only a single ulcer. Women frequently have four or more ulcers, with fewer symptoms.

The initial ulcer may be mistaken as a "hard" chancre, the typical sore of primary syphilis, as opposed to the "soft chancre" of chancroid.

Approximately one-third of the infected individuals will develop enlargements of the inguinal lymph nodes, the nodes located in the fold between the leg and the lower abdomen.

Half of those who develop swelling of the inguinal lymph nodes will progress to a point where the nodes rupture through the skin, producing draining abscesses. The swollen lymph nodes and abscesses are often referred to as buboes.





Clinical variants[edit]

Some of clinical variants are as follows.[4]

Dwarf chancroidSmall, superficial, relatively painless ulcer.
Giant chancroidLarge granulomatous ulcer at the site of a ruptured inguinal bubo, extending beyond its margins.
Follicular chancroidSeen in females in association with hair follicles of the labia majora and pubis; initial follicular pustule evolves into a classic ulcer at the site.
Transient chancroidSuperficial ulcers that may heal rapidly,followed by a typical inguinal bubo.
Serpiginous chancroidMultiple ulcers that coalesce to form a serpiginous pattern.
Mixed chancroidNonindurated tender ulcers of chancroid appearing together with an indurated nontender ulcer of syphilis having an incubation period of 10 to 90 days.
Phagedenic chancroidUlceration that causes extensive destruction of genitalia following secondary or superinfection by anaerobes such as Fusobacterium or Bacteroides.
Chancroidal ulcerMost often a tender, nonindurated, single large ulcer caused by organisms other than Haemophilus ducreyi; lymphadenopathy is conspicuous by its absence.

Laboratory findings[edit]

From bubo pus or ulcer secretions, H. ducreyi can be identified. PCR-based identification of organisms is available. Simple, rapid, sensitive and inexpensive antigen detection methods for H. ducreyi identification are also popular. Serologic detection of H. ducreyi is and uses outer membrane protein and lipooligosaccharide.

Differential diagnosis[edit]

CDC's standard clinical definition for a probable case of chancroid
  1. Patient has one or more painful genital ulcers. The combination of a painful ulcer with tender adenopathy is suggestive of chancroid; the presence of suppurative adenopathy is almost pathognomonic.
  2. No evidence of Treponema pallidum infection by darkfield microscopic examination of ulcer exudate or by a serologic test for syphilis performed greater than or equal to 7 days after onset of ulcers and
  3. Either a clinical presentation of the ulcer(s) not typical of disease caused by herpes simplex virus (HSV) or a culture negative for HSV.

Despite many distinguishing features, the clinical spectrums of following diseases may overlap with chancroid:

Comparison with syphilis[edit]

There are many differences and similarities between the conditions syphilitic chancre and chancroid.



The CDC recommendation for chancroid is a single oral dose (1 gram) of azithromycin, or a single IM dose of ceftriaxone, or oral erythromycin for seven days.

Abscesses are drained.

H. ducreyi is resistant to sulfonamides, tetracyclines, penicillins, chloramphenicol, ciprofloxacin, ofloxacin, trimethoprim and aminoglycosides. Recently, several erythromycin resistant isolates have been reported.[4]

Treatment failure is possible with HIV co-infection and extended therapy is sometimes required.



Chancroid spreads in populations with high sexual activity, such as prostitutes. Use of condom, prophylaxis by azithromycin, syndromic management of genital ulcers, treating patients with reactive syphilis serology are some of the strategies successfully tried in Thailand.[4]


Prognosis is excellent with proper treatment. Treating sexual contacts of affected individual helps break cycle of infection.


Chancroid has been known to humans since time of ancient Greeks.[6] Some of important events on historical timeline of chancre are:

1852Leon Bassereau distinguished chancroid from syphilis (i.e. soft chancre from hard chancre)
1890sAugusto Ducrey identified H. ducreyi
1900Benzacon and colleagues isolated H. ducreyi
1970sHammond and colleagues developed selective media

External links[edit]


  1. ^ James, William D.; Berger, Timothy G.; et al. (2006). Andrews' Diseases of the Skin: clinical Dermatology. Saunders Elsevier. p. 274. ISBN 0-7216-2921-0. 
  2. ^ Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. ISBN 1-4160-2999-0. 
  3. ^ 
  4. ^ a b c d CURRENT Diagnosis & Treatment of Sexually Transmitted Diseases. McGraw-Hill Companies,Inc. 2007. pp. 69–74. ISBN 9780071509619. 
  5. ^ Medical Microbiology: The Big Picture. McGraw Hill Professional. p. 243. ISBN 9780071476614. 
  6. ^ Sexually Transmitted Diseases, 4th ed. McGraw Hill Professional. 2007. pp. 689–698. ISBN 9780071417488.