Actinomyces viscosus
Taxonomy
Morphology
Cultural characteristics
Biochemical characters
Ecology
Pathogenicity
References
Phylum Actinobacteria, Class Actinobacteria, Subclass Actibacteridae, Order Actynomycetales, Suborder Actinomycinae, Family
Actinomycetaceae, Genus Actinomyces,
Actinomyces viscosus (Howell, Jordan, Georg and Pine 1965) Georg, Pine and Gerencser
1969.

Historical synonyms:
Odontomyces viscosus Howell, Jordan, Georg and Pine 1965.
Gram-positive irregular, diphtheroid or branched rods, occurring filaments. Non-motile.
Non-spore-forming.
Colonies are small, smooth, granular surface, dense center with a filamentous fringe
or entire edge, after 24-48 h on BHI agar incubated aerobically with CO
2; after 7 days
the colonies are 1.0-2.0 mm in diameter on BHI agar, convex to heaped, circular,
entire, opaque, cream to white, soft or mucoid,  smooth and glistening, sometime
with aerial hyphae. Hamster strains have an eccentric pit and a granular or frosty
appearance. Human strains show various radial or concentric striations and shallow
central depressions. Smooth colonies are low convex, transparent with an optically
dark central “core”. In BHI broth growth is diffuse, with a viscous sediment wich gives
a mucoid or viscous rope when swirled. Facultative anaerobic. Grows better in the
presence of CO
2. Grows at 35-37 ºC, optimally. Alpha haemolysis may occur.
Oral cavity of hamsters, rats and man is normal habitat. There are two serotypes.
Periodontal disease with subgingival plaque occurs spontaneously in hamsters and may be produced experimentally in hamsters
and mice with hamster strains.
  1. Slack J.M., 1975. Genus Actinomyces Harz 1877 . In: Buchanan R.E. and Gibbons N.E. (Editors), Bergey’s Manual of
    Determinative Bacteriology, Eight Edition, The Williams & Wilkins Company, Baltimore, 660-667.
  2. Johnson J.L., Moore L.V.H., Kaneko B. and Moore W.E.C., 1990. Actinomyces georgiae sp. nov. , Actinomyces gerencseriae sp.
    nov. , Designation of Two Genospecies of Actinomyces naeslundii, and Inclusion of A. naeslundii serotypes II and III and
    Actinomyces viscosus serotype II in A. naeslundii Genospecies 2. Int J Syst Bacteriol Vol. 40, No. 3, 273-286.
Non-acid-fast.

Positive results for catalase, H
2S production, methyl red, nitrate reduction, starch hydrolysis (weak reaction), acid production from:
fructose, glucose, glycerol, inositol, lactose, maltose, mannose, raffinose, starch and sucrose (saccharose).

Negative results for esculin hydrolysis, gelatin hydrolysis, indole production, urease, Voges-Proskauer, acid production from: adonitol,
amygdalin, arabinose, dulcitol, esculin, glycogen, mannitol, ribose, rhamnose, sorbitol and xylose.

Variable results for acid production from: cellobiose, galactose, inulin, melibiose, salicin and trehalose.
(c) Costin Stoica
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