23 plus species including:


Actinomyces bovis
Actinomyces denticolens
Actinomyces eriksonii
Actinomyces georgiae
Actinomyces gerencseriae
Actinomyces hordeovulneris
Actinomyces howelli
Actinomyces humiferus
Actinomyces hyovaginalis
Actinomyces israelii
Actinomyces madurae
Actinomyces meyeri
Actinomyces naeslundii
Actinomyces neuii
Actinomyces odontolyticus
Actinomyces propionica
Actinomyces pyogenes
Actinomyces slackii
Actinomyces suis
Actinomyces viscosus


Gram Stain: Positive. Although they are gram-positive, they often stain irregularly with a beaded appearance, non-acid-fast.
Morphology: Slender or slightly curved rods with true branching.
Size: 0.2 - 1.0 micrometers by 2.0 - 5.0 micrometers.
Motility: They are non-motile.
Capsules: No.
Spores: No endospores or conidia are produced.
Other: Short rods, often with clubbed ends may occur singly, in pairs, in "V" and "Y" arrangements or in short chains or clusters.


Colonies are mycelial or rough and crumbly in texture, occasionally with a red pigment.


Chemoorganoheterotrophic; primarily fermentative; carbohydrates fermented anaerogenically.



Primarily, as normal inhabitants of mucosal surfaces of man and other animals, opportunistic pathogens vary considerably in virulence.


Apart from A. denticolens and A. howellii, whose pathogenic potentials have not been investigated so far, all of the other typical Actinomyces species may cause various forms of disease in man as well as in feral, domestic, and laboratory animals. Nevertheless, members of different species vary considerably with regard to virulence, types of pathological lesions induced and host specificity. Typical diseases and impairments caused by Actinomyces species in humans are: actinomycoses, ocular infections, periodontal disease, carries and intrauterine infections. As currently recognized, actinomycoses are endogenous, subacute to chronic, granulomatous inflammatory process that give rise to suppuration, abscess formation and development of draining sinus tracks. Among these pathological conditions, actinomycoses are undoubtably the most characteristic disease entities produced in man by members of the genus Actinomyces.


For culture: Cooked Meat Medium, Thioglycollate Broth with Supplements, Blood Agar, 5%, Brain Heart Infusion Agar (BHIA), or Tryptic Soy Agar.
For selective isolation: No media recommended.
For maintenance: Cooked Meat Medium or Tryptic Soy Agar.
For transport: Stuart medium. (Reduced, transport media should be used).


Temperature: 35 - 37 degrees C.
Time: 7 - 14 days.
Atmosphere: Anaerobic.


1. Holt, J.G., et al. 1994. Bergey's Manual of Determinative Bacteriology, 9th ed. Williams & Wilkins, Baltimore, MD.

2. Holt, J.G., et al. 1986. Bergey's Manual of Systemic Bacteriology, Volumes I & II. Williams & Wilkins, Baltimore, MD.

3. The Oxoid Vade-Mecum of Microbiology. 1993. Unipath Ltd., Basingstoke, UK.

4. Murray, P.R., et al. 1995. Manual of Clinical Microbiology, 6th ed. American Society for Microbiology, Washington, D.C.

5. Internet: Database Search, February, 1998.