|Tannerella, Porphyromonas and Prevotella
Tannerella forsythia-----Forormerly Bacteroides forsythus and Tannerella forsythensis.
Mainly colonize the oropharynx.
Habitat and Transmission :
Both supragengival and subgengival sites but more common in the later . The degree of isolation strongly related to increasing pocket depth and increasingly recovered from sites that converted from periodontal health to disease and sites with periodontal breakdown . Hence considered a consensus periodontal pathogen.
Anaerobic gram negative bacilli of medical interest .
Culture and Identification;
Grows anaerobically, but some times requires up to 14 days for visible growth . Growth enhanced by co-cultivation with Fusobacterium nucleatum . Media supplemented with N-acetylmuramic acid enhances growth.
Pathogenicity----- Periodontal pathogen in both human and animals; induces apoptotic cell death ;invades epithelial cells in vetro and in vivo. Its endotoxins ,fatty acids and methylglyoxal production are considered virulence factors, increased levels found in ligature- induced periodontitis and peri – implantitis in dogs .
There are two species in genus porphyromonas , P. gengivalis and P. endodontalis .
Habitat and Transmission :
Found almost solely at subgingival sites, particularly in advanced periodontal diseases, so this organism considered a consensus periodontal pathogen. Some times recovered from the tongue and tonsils.
Non motile, asacharolytic, short pleomorphic , gram- negative coccobacilli.
Culture and Identification :
This microorganism grows anaerobically with dark pigmentation on media containing lysed blood.
It can be identified by biochemical characteristics using commercially available kits ( AnIdent ), DNA and molecular probes are now used to identify this organisms directly from plaques samples.
Pathogenicity: an aggressive periodontal pathogen in both human and animals (eg. guinea pigs, monkeys, beagles dogs ) ; its fimbria mediate adhesion and the capsule defends against phagocytosis.
Also the organism produces a range of virulence factors including collaginase, endotoxins, fibrinolysin, phospholypase A, many proteases,that destroy immunoglobulins, gingipain, a fibroblast- inhibitory factors, complement and haem-sequestering proteins and hemolysin.
Porphyromonas gingivalis image
Prevotella nigrescens The main
Prevotella melaninogenica colonization site
Prevotella loescheiisite is oropharynx
Prevotella pallens The main colonization
Prevotella corporis sites are vagina and
Prevotella: This genus includes a number of pigmented as well as non – pigmented species that are moderately saccharolytic, all produce acetic and succinic acid from glucose.
Prevotella melaninogenica is the type species.
Habitate and Transmission: The predominant ecological nich of all prevotella species appear to be the human oral cavity. Strains of Prevotella intermedia are associated more with periodontal disease, while P.
Nigrescens is isolated more often from healthy gingival sites.
Culture and Identification
Non –motile, short, round-ended, Gram-negative rods, brown- black colonies on blood agar (when pigmented ) . Molecular techniques are required to differentiate some species.
Prevotella intermedia is closely associated with periodontal disease and shares a number of virulence properties exhibited by Porphyromonas gingivalis .
The pathogenicity of other subdivided species await clarification.
Oral non- pigmented species such as P.buccae, P. oralis, P. dentalis are isolated on occasion from healthy subgingival plaque. Some of the latter are associated with disease, and increase in numbers and proportions during periodontal disease.
Prevotella intermedia image