Introduction

Chancroid is a sexually transmitted bacterial infection of the genital skin or mucous membranes caused by Haemophilus ducreyi.

It is highly contagious yet curable and not a common infection in the UK. It is characterized by the presence of painful ulcers and inguinal lymphadenopathy. It is still occasionally known by its old names of 'soft sore' or 'soft chancre'.

Epidemiology

  • Incidence: 0.05 cases per 100,000 person-years
  • Peak incidence: 30-40 years
  • Sex ratio: 1:1
Condition Relative
incidence
Genital herpes6000.00
Syphilis200.00
Chancroid1
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+

Aetiology

Haemophilus ducreyi is the causative organism in chancroid. It is usually transmitted by sexual intercourse. Worldwide, chancroid appears to have declined as well but it is more prevalent in Africa, the Caribbean Basin, and Southwest Asia.

Risk factors
  • Multiple sexual partners
  • Lower socioeconomic status
  • Drug abuse

Pathophysiology

It is caused by Haemophilus ducreyi, a gram-negative facultative anaerobic bacillus.

It is transmitted through:
  • Sexual transmission by skin-to-skin contact with an open sore.
  • Non-sexual transmission when pus-like fluid from the ulcer is moved to other parts of the body such as the eye and skin or to another person.

The organism has an incubation period of 1 day to 2 weeks and it enters the skin through disrupted mucosa or skin of the external genitalia and colonises subcutaneous tissues, then produces toxins that damages the tissue which results in an ulcer formation.

The disease typically begins as a small inflammatory papule at the site of inoculation; within days, the papule may erode to form an extremely painful deep ulcerations.

Clinical features

Most people with chancroid begin to notice symptoms between 3 and 10 days after contracting the infection. The lesion begins as erythematous tender papules that become pustular and later erode to form an extremely painful and deep ulcer with soft ragged, undermined margins. Ulcers vary in size and often coalesce. Deeper erosion occasionally leads to marked tissue destruction.

About 50% of the patients will also have associated inguinal lymphadenopathy which is painful. Other rare symptoms include dysuria and dyspareunia.

Location of chancroid lesions:

  • Males
In men, the most common site of the chancroid infection is the foreskin, but it may also occur less commonly on the shaft, the glans, or the meatus of the penis.

  • Females
In women, labia majora is commonly involved in chancroid, but they may also occur on the labia minora, the thighs, the perineum, or the cervix.

Investigations

Chancroid is usually a clinical diagnosis. There are no laboratory tests currently available for the immediate diagnosis of chancroid.

The main investigative techniques are:
  • Culture and sensitivity
  • PCR (most sensitive)
  • Microscopy
  • Serology

A definitive diagnosis of chancroid requires the identification of Haemophilus ducreyi on special culture media. For many years in vitro culture was the “gold standard” for evaluating chancroid. However, the advent of more sensitive DNA amplification techniques such as polymerase chain reaction (PCR) shows higher sensitivity.

Microscopy is also useful if there is a high load of organisms present that show the characteristic gram-negative bacillus which exhibits an unusual tendency to auto-agglutinate. Microscopically, various morphological forms have been described such as “schools of fish,” “railroad tracks,” and “fingerprints'. However, this method has only limited value because of low sensitivity (5% to 63%) and specificity (51% to 99%).

The serologic diagnosis of chancroid has been useful in a number of epidemiological studies, using enzyme-linked immunoassays. However, for the individual patient, the method lacks sensitivity, specificity and cannot distinguish between remote and recent infection.

Serologic testing for syphilis and HIV and cultures for herpes should be done to exclude other causes of genital ulcers.

Differential diagnosis

Differentials of chancroid include:


Syphilitic ulcer is caused by Treponema pallidum, which is typically painful and non-exudative, whereas chancroid is typically painless and has a grey or yellow purulent exudate. However, both lesions can be present at multiple sites with multiple lesions and classically appear on the genitals of infected individuals.

Genital herpes is caused by Herpes Simplex Virus. Usually, it appears as multiple vesicular lesions that rupture and become painful shallow ulcers. Ulcers are shallower than chancroid lesions with a clean base. It is more commonly associated with systemic symptoms such as fever, headache and malaise.






Management

Successful treatment for chancroid cures the infection, resolves the clinical symptoms, and prevents transmission to others.

The recent WHO recommendation is either:
  • A single oral dose (500 mg) of ciprofloxacin, a single IM dose (250 mg) of ceftriaxone or an oral (500 mg) of erythromycin three times a day for seven days.

While the United Kingdom’s Clinical Effectiveness Group recommends either:
  • A single IM dose (250 mg) of ceftriaxone, a single IM dose (1gram) of azithromycin or an oral (500 mg) of erythromycin four times a day for seven days.

Sexual partners of a patient who has chancroid should be examined and treated for chancroid if they have had sexual contact with the patient during 10 days preceding the onset of symptoms in the patient. This is done even if the partners do not have any symptoms.