Actinomyces naeslundii
Taxonomy
Morphology
Cultural characteristics
Biochemical characters
Ecology
Pathogenicity
References
Phylum Actinobacteria, Class Actinobacteria, Subclass Actibacteridae, Order Actynomycetales, Suborder Actinomycinae, Family
Actinomycetaceae, Genus Actinomyces,
Actinomyces naeslundii Thompson and Lovestedt 1951.

Historical synonyms :
Actinomyces naeslundii genospecies 1 (Johnson et al., 1990) Thompson and Lovestedt 1951,  Actinomyces
naeslundii
serotype I,  Thompson and Lovestedt 1951
Gram-positive diphtheroid rods, sometimes occurring in curved or  branched filaments.
Non-motile. Non-spore-forming.
Colonies are flat, round with entire edges, small after 24 h on BHI agar; after 7-14 days
the colonies are 1-3 mm in diameter, convex, smooth or finely granular, white and soft.
In BHI broth grows as a flocculent mass to the top with discreet soft granules below.
Alpha-haemolysis may occur. Facultative anaerobic. Grows at 35-37 ºC, optimally.
No growth at 25 ºC.
Isolated from human sinus and from periodontal flora.
Isolated from patients with gingivitis and periodontitis.
  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. Henssge U., Do T., Radford D.R., Gilbert S.C., Clark D. and Beighton D., 2009. Emended description of Actinomyces naeslundii
    and descriptions of Actinomyces oris sp. nov. and Actinomyces johnsonii sp. nov., previously identified as Actinomyces naeslundii
    genospecies 1, 2 and WVA 963. Int J Syst Evol Microbiol. 59, 509-516.
  3. 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 I1 and I11 and
    Actinomyces viscosus serotype II in A. naeslundii Genospecies 2. Int J Syst Bacteriol Vol. 40, No. 3, 273-286.
Non-acid-fast.
Decription is based on API Rapid ID 32A results.

Positive results for esculin hydrolysis, alpha- and beta-galactosidase , alpha- and beta-glucosidase, leucine arylamidase, methyl red,
nitrate reduction, acid production from: fructose, glucose, inositol, maltose, mannose, melibiose & sucrose.

Negative results for alkaline phosphatase, arginine dihydrolase, catalase, alpha-fucosidase, gelatin hydrolysis, hippurate hydrolysis,
indole production, beta-glucuronidase, N-acetyl-beta-glucosaminidase, pyrrolidonyl arylamidase, urease, Voges-Proskauer test, acid
production from: amygdalin, D-arabinose, glycogen, mannitol, melezitose, raffinose, rhamnose, sorbitol, starch & xylose.

Variable results for acid production from: cellobiose, esculin, lactose, ribose, salicin & trehalose.
(c) Costin Stoica
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