Actinomyces and related genera

Definition gram-positive rods, μm straight, curved, or pleomorphic singly, in pairs, clusters, short chains or filaments Non acid fast, Non motile do not form endospores or conidia. facultative anaerobes ( some are obligately anaerobic) The optimum temperature for growth of all species is ‘C Carbohydrates are fermented There is little action on proteins G + C content of the DNA is 55-71mol% type species is A. bovis.

Habitat Intestinal surfaces, mucous membranes of humans and animals. Normal flora of the oral cavities of humans and animals, where they occur as components of dental plaque on teeth and biofilms on mucosal surfaces A. israelii is regularly present in the female genital tract

Morphology appear beaded on Gram's stain on blood agar, the majority of species show diphtheroidal V and Y forms and may produce short coccobacilli Several different cellular morphologies can occur together and often cells form clusters. Some species, including,A.israelii

Colonial morphology Species such as A. israelii, which form long branching fllaments, usually produce a granular deposit in broth with a completely clear supernateA. naeslundii, A. viscosus, and Actinomyces gerencseriae, which produce fewer, shorter filaments, also form a deposit in broth, but it is viscous and ropy and more easily suspended. Organisms that produce diphtheroidal or coccobacilliary cells usually grow as evenly dispersed suspensions. On solid media, Actinomyces spp. produce a variety of colony forms. Typically, A. israelii produces a white-colored, rough, 'molar tooth' colony A. naeslundii, A. viscosus, and A. gerencseriae usually produce convex, smooth, matt-surfaced creamcolored colonies A. graevenitTli colonies have been described as rough, dry, and adherent to blood agar Colonies of other species may be flat (A. hyovaginalis) or low convex (Actinomyces neuii)

LABORATORYIS OLATIONA ND IDENTIFICATION Detection of Actinomyces in clinical specimens by FA avoids the need for culture Isolation of Actinomyces from clinical and other specimens is relatively easy if certain criteria are met 1.appropriate sample taking and transport 2. use of high quality media, or in certain cases selective media 3.incubation in an atmosphere with CO2 or in broth media 4.with HCO3- 5.incubation for a sufficient period of time 6.adequate spreading of sample on solid media 7.careful examination of colonies

Samples Pus or Exudate Macroscopic ( sulfur granules (druzen or Enriched culture of Actinomyces Plated Directly, or after dilution in broth or reduced transport fluid Microscopic FA Staining Oral cavity saliva, swabs of mucosal surfaces, plaque Reduced transport fluid Plating + -

Culture good quality digest nutrient agar Serum or blood heminvitamin K1CO2 incubation for 7-14 days optimum temperature ( 35-37’C )

Identification SpeciesGenus Suspicious colony Pure culture FA staining Electrophoresis of whole cell proteins and enzymes Analysis of acid endproducts commercial systems Cell wall composition phenotypic tests

TYPING METHODS 1.Serotyping Little is known of the antigens that define the serotypes Little is known of any specific r relationships between Actinomyces serotypes and pathogenicity 2.Genetic typing Restriction fragment length polymorphism (RFLP) analysis of total DNA Ribotyping Amplified 165 ribosomal DNA restriction analysis (ARDRA)

ROLE IN THE NORMAL FLORA O F HUMANS Aid in the protection of the host from colonization by exogenous pathogens Play a role in maintaining the integrity of oral biofilm communities.

Pathogenicity and Virulence Human – cervicofacial region – genital tract of healthy females – mixed infections – root surface caries, and periodontal disease Animal – lumpy jaw