Aggregatibacter aphrophilus
Cultural characteristics
Biochemical characters
Phylum Proteobacteria, Class Gammaproteobacteria, Order Pasteurellales, Family Pasteurellaceae, Genus Aggregatibacter,
Aggregatibacter aphrophilus
(Khairat 1940) comb. nov. Norskov-Lauritsen and Kilian 2006.
Old synonyms:
Haemophilus aphrophilus Khairat 1940, Haemophilus paraphrophilus Zinnemann, Rogers, Frazer and Boyce 1968.
Gram negative, 0.45-0.55 / 1.5-1.7 µm short  rods; occasional filamentous forms.
Surface-associated thin hairlike structures of an unidentified nature have been
Colonies on chocolate agar incubated in air supplemented with 10% CO2 are high
convex, granular, yellowish, opaque, 1.0-1.5 mm in diameter within 24 h; without CO
2 ,
the growth is characteristically stunted , with very small colonies interspersed with a
few larger colonies.
Growth in broth media is granular, with a heavy sediment and adhering colonies on
the walls, which are difficult to remove. Nonhemolytic.
Aerobic, facultatively anaerobic, require X-factor; often become independent upon
subcultivation. V-factor requirement is variable (negative for strains formerly
Haemophilus aphrophilus and positive for strains formerly Haemophilus
). CO2 is required for growth. Growth on Mac Conkey agar is  negative.
Occurs in the mouth and oropharynx of healthy individuals. It's a frequent member of the microflora of human dental plaque, particularly
between the teeth and in the gingival pockets.
Has been isolated from blood, spinal fluid, peritoneum, pleura, wounds and jaw infections.
Has been reported to occur in pharynx of pet dogs.
Surface-associated thin hairlike structures of an unidentified nature have been demonstrated.
Opportunistic pathogen occasionally causes endocarditis and brain abscesses in humans.
Has been isolated from blood, spinal fluid, wounds, and jaw infections.
  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,
  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.
  6. Zinnemann K., Biberstein E. L., 1975. Genus Haemophilus. In: Buchanan R.E., Gibbons N.E.(Ed.) Bergey’s Manual of
    Determinative Bacteriology, 8-edition, Williams & Wilkins, 364-370.
  7. N. Norskov-Lauritsen and M. Kilian, 2006. Reclassification of Actinobacillus actinomycetemcomitans, Haemophilus
    aphrophilus, Haemophilus paraphrophilus and Haemophilus segnis as Aggregatibacter actinomycetemcomitans gen.nov.,
    comb. nov., Aggregatibacter aphrophilus comb. nov.and Aggregatibacter segnis comb. nov., and emended description of
    Aggregatibacter aphrophilus to include V factor-dependent and V factor-independent isolates.IJSEM, 56, 2135-2146.
Positive results for nitrates reduction, ONPG, alkaline phosphatase, acid production from: D(+) glucose (with gas), D(-) fructose, D(+)
galactose, D(+) mannose, lactose, maltose, sucrose (saccharose), trehalose & raffinose.

Negative results for oxidase, catalase, H
2S production, urease, arginine dehydrolase, lysine decarboxylase, ornithine decarboxylase,
indole production, acid production from: xylitol, L(+) arabinose,  dulcitol, mannitol, D(-) sorbitol, L(+) rhamnose, L(-) sorbose,
cellobiose, D(+) melibiose, inulin, esculin & salicin.

Variable results for alpha-glucosidase, acid production from: glycerol,  D(+) xylose & meso-inositol.
(c) Costin Stoica
Culture media
Biochemical tests
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