Haemophilus ducreyi
Taxonomy
Morphology
Cultural characteristics
Biochemical characters
Ecology
Pathogenicity
References
Phylum Proteobacteria, Class Gammaproteobacteria, Order Pasteurellales, Family Pasteurellaceae, Genus Haemophilus,  
Haemophilus ducreyi
(Neveu-Lemaire 1921) Bergey, Harrison, Breed, Hammer and Huntoon 1923.

Historical synonyms:
Bacillus ulceris cancrosi  Kruse 1896, Coccobacillus ducreyi Neveu-Lemaire 1921.
Gram-negative, 0.5/1,5-2.0 µm, slender  rods in pairs or chains; “school of fish”-like
arrangements. Capsules have not been detected. Fine tangled pili composed of a
unique major protein subunit of 24 kDa.
Colonies on chocolate agar are smooth, flat, grayish, translucent, small (0.5 mm in
diameter) after 72 h, but often with a few interspersed larger colonies having an
otherwise identical appearance.
Hemolysis is variable.
Aerobic, facultatively anaerobic, require X-factor but not V-factor for growth. CO
2
requirement is variable.
Growth on Mac Conkey agar is negative. Growth is poor on most laboratory media.
Isolated from humans suffering of venereal disease “soft chancre “ or “chancroid”. A carrier state in healthy individuals has not been
detected.
Fine tangled pili composed of a unique major protein subunit of 24 kDa.
Produces a cell-associated hemolysin with cytotoxic activity and a soluble cytotoxin.
Causes the human venereal disease “soft chancre “ or “chancroid”.
Disease experimentally reproduced by intradermic inoculation  in rabbit and monkey.
  1. Mogens Kilian, 2004. Genus III. Haemophilus. In: Bergey’s Manual of Systematic Bacteriology, Second edition, Vol two, part B,
    George M. Garrity (Editor-in-Chief), pp. 883-904.
  2. Mary P.E. Slack, 2006. Haemophilus. In: Topley & Wilson’s Microbiology and Microbial Infections, 10 edition, Vol. 2,
    Bacteriology, Edward Arnold Ltd.
  3. Pozsgi N., 1985. Genul Pasteurella. In: Bacteriologie medicala, vol II, V. Bilbiie, N. Pozsgi (sub redactia), Ed. Medicala,
    Bucuresti,123-130.
  4. N. Mihancea si colab., 2009. Identificarea genului Haemophilus. In: Tratat de microbiologie clinica, D. Buiuc, M. Negut, Ed.
    Medicala, Bucuresti, 797-809.
  5. J. G. Holt et al., 1994. Facultatively Anaerobic Gram-Negative Rods. Subgroup 3. Family Pasteurellaceae. In: Begey’s Manual
    of Determinative Bacteriology, 9th-edition, Williams & Wilkins, pp 194-196.
Positive results for nitrates reduction, oxidase, alkaline phosphatase, acid from D(+) glucose (weak, without gas) & maltose.

Negative results for H
2S production, catalase, urease, arginine dehydrolase, lysine decarboxylase, ornithine decarboxylase, indole
production,
alpha-glucosidase, ONPG, acid production from: glycerol, xylitol, L(+) arabinose, D(+) xylose, dulcitol, meso-inositol,
mannitol, D(-) sorbitol, D(-) fructose, D(+) galactose, D(+) mannose, L(+) rhamnose, L(-) sorbose, cellobiose, lactose, ONPG, D(+)
melibiose, sucrose (saccharose), trehalose, raffinose, inulin, esculin
& salicin.
(c) Costin Stoica
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