Haemophilus ducreyi

Haemophilus ducreyi is a fastidious gram-negative coccobacillus bacteria.

Haemophilus ducreyi
Photomicrograph of H. ducreyi
Scientific classification
Kingdom:
Bacteria
Phylum:
Proteobacteria
Class:
Gamma Proteobacteria
Order:
Pasteurellales
Family:
Pasteurellaceae
Genus:
Haemophilus
Species:
H. ducreyi
Binomial name
Haemophilus ducreyi
(Neveu-Lemaire 1921)
Bergey et al. 1923

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-like azithromycin and a third-generation cephalosporin such as 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.[2]

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" test.[3]

See also
  • Sexually transmitted disease

References
  1. Lewis, DA; Mitjà, O (February 2016). "Haemophilus ducreyi: from sexually transmitted infection to skin ulcer pathogen". Current Opinion in Infectious Diseases. 29 (1): 52–7. doi:10.1097/QCO.0000000000000226. PMID 26658654.
  2. Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. p. 1256. ISBN 978-1-4160-2999-1.
  3. Alfa, Michelle (2005). "The laboratory diagnosis of Haemophilus ducreyi". Canadian Journal of Infectious Diseases and Medical Microbiology. 16 (1): 34–35. doi:10.1155/2005/851610. PMC 2095004. PMID 18159525.
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