Haemophilus ducreyi is a fastidious gram-negative coccobacillus bacteria.
It causes the sexually transmitted disease chancroid, a major cause of genital ulceration in developing countries characterized by painful sores on the genitalia. Chancroid starts as an erythematous papular lesion that breaks down into a painful bleeding ulcer with a necrotic base and ragged edge. More recently, it has also been found to cause chronic skin ulceration away from the genitalia, infect children and adults, and behave in a manner that mimics yaws. These strains seem to have diverged quite recently.[1]
H. ducreyi can be cultured on chocolate agar. It is best treated with a macrolide, e.g. azithromycin, and a third-generation cephalosporin, e.g. ceftriaxone. H. ducreyi gram stain resembles a "school of fish."
| Haemophilus ducreyi | |
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| Photomicrograph of H. ducreyi | |
| Scientific classification | |
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| Species: | H. ducreyi |
| Binomial name | |
| Haemophilus ducreyi (Neveu-Lemaire 1921) Bergey et al. 1923 | |
https://en.wikipedia.org/wiki/Haemophilus_ducreyi
H. ducreyi is an opportunistic microorganism that infects its host by way of breaks in the skin or epidermis. Inflammation then takes place as the area of infection is inundated with lymphocytes, macrophages, and granulocytes. This pyogenic inflammation causes regional lymphadenitis in the sexually transmitted disease chancroid.[2]
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.[8]
Syphillus - Chancre - Lympathadenopathy - Adeno bubuloules
| Phagedenic chancroid | Ulceration that causes extensive destruction of genitalia following secondary or superinfection by anaerobes such as Fusobacterium or Bacteroides. |
Despite many distinguishing features, the clinical spectrums of following diseases may overlap with chancroid:[citation needed]
Practical clinical approach for this STI as Genital Ulcer Disease is to rule out top differential diagnosis of Syphilis and Herpes and consider empirical treatment for Chancroid as testing is not commonly done for the latter.[citation needed]
Comparison with syphilis[edit]
There are many differences and similarities between the conditions syphilitic chancre and chancroid:[10]
- Similarities
- Both originate as pustules at the site of inoculation, and progress to ulcerated lesions
- Both lesions are typically 1–2 cm in diameter
- Both lesions are caused by sexually transmissible organisms
- Both lesions typically appear on the genitals of infected individuals
- Both lesions can be present at multiple sites and with multiple lesions
- Differences
- Chancre is a lesion typical of infection with the bacterium that causes syphilis, Treponema pallidum
- Chancroid is a lesion typical of infection with the bacterium Haemophilus ducreyi
- Chancres are typically painless, whereas chancroid are typically painful
- Chancres are typically non-exudative, whereas chancroid typically have a grey or yellow purulent exudate
- Chancres have a hard (indurated) edge, whereas chancroid have a soft edge
- Chancres heal spontaneously within three to six weeks, even in the absence of treatment
- Chancres can occur in the pharynx as well as on the genitals
Pregnant and lactating women, or those below 18 years of age regardless of gender, should not use ciprofloxacin as treatment for chancroid. Treatment failure is possible with HIV co-infection and extended therapy is sometimes required.[citation needed]
Chancroid has been known to humans since time of ancient Greeks.[13] Some of important events on historical timeline of chancre are:
| Year | Event |
|---|---|
| 1852 | Leon Bassereau distinguished chancroid from syphilis (i.e. soft chancre from hard chancre) |
| 1890s | Augusto Ducrey identified H. ducreyi |
| 1900 | Benzacon and colleagues isolated H. ducreyi |
| 1970s | Hammond and colleagues developed selective media |
- Superinfection by Fusarium and Bacteroides. These later require debridement and may result in disfiguring scars.
Complications[edit]
- Extensive lymph node inflammation may develop.
- Large inguinal abscesses may develop and rupture to form draining sinus or giant ulcer.
- Superinfection by Fusarium and Bacteroides. These later require debridement and may result in disfiguring scars.
- Phimosis can develop in long-standing lesion by scarring and thickening of foreskin, which may subsequently require circumcision.
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