''Haemophilus ducreyi'' is a fastidious

gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wa ...

coccobacillus bacteria. It causes the

sexually transmitted disease Sexually transmitted infections (STIs), also referred to as sexually transmitted diseases (STDs) and the older term venereal diseases, are infections that are spread by sexual activity, especially vaginal intercourse, anal sex, and or ...

chancroid Chancroid ( ) 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. However, there have been reports of accident ...

, 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 Yaws is a tropical infection of the skin, bones, and joints caused by the spirochete bacterium ''Treponema pallidum pertenue''. The disease begins with a round, hard swelling of the skin, in diameter. The center may break open and form an ulc ...

. These strains seem to have diverged quite recently. ''H. ducreyi'' can be cultured on

chocolate agar Chocolate agar (CHOC) or chocolate blood agar (CBA), is a nonselective, enriched growth medium used for isolation of pathogenic bacteria. It is a variant of the blood agar plate, containing red blood cells that have been lysed by slowly heating ...

. It is best treated with a

macrolide The Macrolides are a class of natural products that consist of a large macrocyclic lactone ring to which one or more deoxy sugars, usually cladinose and desosamine, may be attached. The lactone rings are usually 14-, 15-, or 16-membered. Ma ...

, e.g. azithromycin, and a third-generation

cephalosporin The cephalosporins (sg. ) are a class of β-lactam antibiotics originally derived from the fungus ''Acremonium'', which was previously known as ''Cephalosporium''. Together with cephamycins, they constitute a subgroup of β-lactam antibiotics ...

, e.g. ceftriaxone. ''H. ducreyi'' gram stain resembles a "school of fish."

Pathogenesis

''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.

Diagnosis

Although antigen detection, serology, and genetic amplification methods are sometimes used to diagnose infections with ''H. ducreyi'' and the genetic tests have greater sensitivity, they are not widely available, so cultures are currently considered the "

gold standard A gold standard is a monetary system in which the standard economic unit of account is based on a fixed quantity of gold. The gold standard was the basis for the international monetary system from the 1870s to the early 1920s, and from th ...

" test.

Treatment

The first line treatments are one of four options : azithromycin 1 g orally in a single dose, ceftriaxone 250 mg intramuscularly in a single dose, ciprofloxacin 500 mg orally 2 times a day for 3 days, or erythromycin base 500 mg orally 3 times a day for 7 days.

References

External links

''Haemophilus ducreyi''
at the NCBI Taxonomy Browser
Type strain of ''Haemophilus ducreyi''
at Bac''Dive'', the Bacterial Diversity Metadatabase {{DEFAULTSORT:Haemophilus Ducreyi ducreyi Bacteria described in 1923 Taxa named by Maurice Neveu-Lemaire

Pathogenesis

Diagnosis

Treatment

See also

References

External links