unit 18 - Strict anaerobic Gram-negative bacteria of dental interest

Effect of oxygen on obligate anaerobes

Oxygen is harmful

obligate anaerobes

Bacteroides spp. general habitat

Predominantly intestinal tract

obligate anaerobes

Most important Bacteroides species

Bacteroides fragilis

obligate anaerobes

Tannerella spp. general trait

Black-pigmented anaerobic rods

obligate anaerobes

Key Tannerella species

Tannerella forsythia

obligate anaerobes

Tannerella clinical relevance

Major periodontal pathogen

obligate anaerobes

Key Porphyromonas species

Porphyromonas gingivalis

obligate anaerobes

Porphyromonas oral role

Normal oral microbiota but is an agent of periodontal disease

obligate anaerobes

Prevotella spp. general trait

Saccharolytic Gram-negative anaerobes

Prevotella habitat

Oral and genitourinary tract

obligate anaerobes

some species of Prevotella spp are associated with

periodontal diease

Black-pigmented anaerobes group

• Tannerella

• Porphyromonas

• Prevotella

the red complex means bacteria associated with

periodontal disease

which bacteria are in the RED COMPLEX

• T. forsythia

• P. gingivalis

• Treponema denticola

Bacteroides

B.Fragilis

Gram reaction

Gram-negative

Bacteroides

B.Fragilis

oxygen requirement

Strict anaerobes

Bacteroides

B.Fragilis

spore formation

Non-sporing

Bacteroides

B.Fragilis

motility

Non-motile

Bacteroides

B.Fragilis

what is the most important virulent factor

Polysaccharide capsule

Primary habitat of B.Fragilis

Intestinal tract

B.Fragilis causes what type of infection

serious anaerobic infections

B.Fragilis

the infections are ……..

endogenous

B.Fragilis

are the endogenous infections and diseases impossible to treat or possible

impossible

what are the main virulent factors of B.Fragilis (other than the capsule)

• endotoxin

• proteases

(produces these)

are B.Fragilis infections usually single or mixed ?

many infections are polymicrobial in nature

how do facultative anaerobes coliforms help B.Fragilis

they use oxygen and facilitate the growth of anaerobic Bacteroides

which antibiotics is B.Fragilis sensitive to

• Metronidazole

• Clindamycin

what enzyme does B.Fragilis produce that contributes to resistance

B-lactamase

to which antibiotics is B.Fragilis resistant

• penicillin’s

• (first generation cephalosporins and aminoglycosides)

genus = Tannerella

T.Forsythia (in exam)

where is it found

Supragingival and subgingival sites

T.Forsythia (in exam)

what is the degree of isolation of T.Forsythia related to

increasing pocket depth

T.Forsythia (in exam)

which sites is it recovered from

• periodontal disease sites

• periodontal breakdown

T.Forsythia (in exam)

motility

non-motile

T.Forsythia (in exam)

shape and gram test

spindle- shaped gram-negative rods

T.Forsythia (in exam)

is it pleomorphic

yes

what diseases is T.Forsythia (in exam) associated with

periodontal disease

what type of pathogen is T.Forsythia (in exam)

a periodontal pathogen (in both humans and animals)

what effect does T.Forsythia (in exam) have on the host cells

induces apoptosis (cell death)

how does T.Forsythia (in exam) interact with epithelial cells

invades epithelial cells in vitro and in vivo

list the main virulent factors of T.Forsythia (in exam) 3

• endotoxin

• fatty acid

• methylglyoxal

Porphyromonas

P.gingivalis

Gram reaction

Gram-negative

Porphyromonas

P.gingivalis

morphology

Short pleomorphic rods

Porphyromonas

P.gingivalis

motility

Non-motile

Porphyromonas

P.gingivalis

spore formation

Non-sporing

Porphyromonas

P.gingivalis

metabolism

Asaccharolytic

P.gingivalis

location

only in subgingival sites

(particularly in periodontal disease (advanced))

P.gingivalis

where can it sometimes be recovered from

tongue and tonsils

P.gingivalis

Porphyromonas gingivalis role in periodontial disease

agressive periodontal pathogen

P.gingivalis

Complex association of P. gingivalis

Red complex

P.gingivalis

what structure mediates mediated adhesion in P.gingivalis

Fimbriae

P.gingivalis

how does it defend against phagocytosis

by its capsule

P.gingivalis

list the main virulent factors

• collagenase

• endotoxin

• fribrinolysin

• phospholipase A

• proteases

• Gingipain

P.gingivalis

what factor inhibits fibroblast activity

Fibroblast-inhibitory factor

P.gingivalis

which proteins help P.gingivalis to interact with blood components

complement and haem-sequestering proteins and haemolysin

prevotella

where is the genus prevotella found

oral cavity

what species of Prevotella is associated with periodontal disease

Prevotella Intermedia

which species of Prevotella is more often isolated from healthy gingival sites

Prevotella nigrescens

Prevotella motility

non motile

provertella shape and gram reaction

gram-negative rods

P.Intermedia

shares virulent factors with

P.gingivalis

P.Intermedia

is part of what complex

orange complex

P.Intermedia

is it a pigmented species

no, its an oral non-pigmented species

P.Intermedia

where are they isolated

healthy subgingival plaque

RED complex bacteria are ….

super virulent factors that cause periodontal disease

RED complex contains

• P.gingivalis

• T.forsythia

• T.denticola

ORANGE COMPLEX bacteria are …

not as virulent as the red complex but still cause periodontal disease

ORANGE COMPLEX BACTERIA are

P.intermedia