1. Periodontal Pathogens

Question 1

Name 3 microorganisms which exist in oral health.

Answer 1

Oral streptococci.
Actinmyces.
Fusobacterium.

Question 2

Name 2 micro-organisms which exist in gingivitis.

Answer 2

Actinmyces.
Prevotella intermedia.

Question 3

Name the three keystone pathogens for severe periodontal disease (red complex) outlined in Socransky’s model.

Answer 3

P. Gingivalis.
T. Forsythia.
T. Denticola.

Question 4

What are the two microbial interactions which exist ?

Answer 4

Competition i.e. dominance.
Co-operation i.e. integration.

Question 5

What are examples of competition microbial interactions ?

Answer 5

Metabolic products like acid conditions, oxidants.
Bacteriocins.
Receptor antagonism.

Question 6

What are examples of co-operation microbial interactions ?

Answer 6

Metabolic products like saccharides, peptides, GFs.
Adhesion substrates.
Immune avoidance.

Question 7

What are the three parts of the ecological plaque hypothesis ?

Answer 7

1. Healthy plaque causing constraint and exclusion of pathogens.
2. Environment modification made - change in commensal community and allow for overgrowth of pathogens.
3. Co-aggregation or co-operation between different species, contributing to model.

Question 8

What is Koch’s postulates (germ theory of disease) ?

Answer 8

Clinical sample collected.
Culture on agar and growth.
Introduced to animal.
Recapitulated from animal.

Question 9

What type of pathogen is P. Gingivalis ?

Answer 9

Gram negative, non-motile, rod, strict anaerobe.

Question 10

What type of pathogen is P. Gingivalis ?

Answer 10

Gram negative, non-motile, rod, strict anaerobe.

Question 11

What are the 6 virulence factors of P. Gingivalis ?

Answer 11

Fimbriae - long and short.
Mixture of degradative enzymes.
Endotoxic, pro-inflammatory LPS.
Capsular polysaccharide and outer membrane vesicles.
Tissue toxic metabolic by-products i.e. ammonia, fatty acids, H2S.
Gingipains.

Question 12

What is the function of long fimbriae ?

Answer 12

Initial attachment and biofilm organisation to surface.

Question 13

What is the function of short fimbriae ?

Answer 13

Cell to cell auto-aggregation and micro-colony formation.

Question 14

What are examples of degradative enzymes associated with periodontal disease ?

Answer 14

Collagenase, fibrolysin, phospholipase A.

Question 15

What are the function of gingipains ?

Answer 15

Provides peptides i.e. nutrition.
Aid attachment.
Activate MMPs causing degradation and remodelling of tissue and degradation of innate receptors and cytokines (IL8).
Subversion of immune system.

Question 16

What type of bacteria is A. Actinomyces ?

Answer 16

Gram negative, facultative anaerobe, non-motile.

Question 17

What virulence factors make A. Actinomyces a periodontal pathogen ?

Answer 17

Production of leukotoxin - breaks up WBCs.
Membrane vesicles.
Glycoprotein matrix.
Fimbriae.
Phase variation i.e. changes antigens.
Subverts host cell immunity.
Bone resorption including factor.

Question 18

What systemic disease risks can be associated with periodontal disease ?

Answer 18

Increased risk of CVD.
Increased risk of rheumatoid arthritis.
Increased risk (x6) of diabetes.

Question 19

What form of periodontitis is P. gingivalis most likely to be associated with ?

Answer 19

Generalised chronic periodontitis.

Question 20

What form of periodontitis is A. Actinomyces most likely to be associated with ?

Answer 20

Localised acute periodontitis.