Microbiology of periodontal disease 2

Question 1

How does microbial pathogenesis work?

Answer 1

• Entry
• Attachment
• Multiplication and consolidation
• Avoiding host defences
• Tissue damage
• Release and spread

Question 2

What are the functions of P. gingivalis

Answer 2

• Cleavage of host defence peptides
• Immune evasion
• Nutrition

Question 3

What do subgingival innate defences include

Answer 3

• Epithelial defences
• Gingival crevicular fluid :
• IgG, IgA, IgM
• Complement
• Lymphocytes
• Polymorphs (neutrophils)
• Defensins

Question 4

What are the common themes of bacterial virulence factors

Answer 4

• Adhesin: enables binding to host tissue
• Invasin: enables invasion of host cell tissue
• Impedin: enables avoidance of host defence mechanisms
• Aggresin: causes direct damage to the host
• Modulin: Induces indirect damage by perturbing regulation of host defences

Question 5

Describe the virulence factors in the capsule

Answer 5

K-antigens, adhesion and resistance to phagocytosis and complement

Question 6

Describe the virulence factors in the fibrils

Answer 6

• Adhesion, gene transfer via conjugation
• Receptors

Question 7

Describe the virulence factors in the extracellular products

Answer 7

Nutrition, host damage interaction with host cells

Question 8

Describe the virulence factors in the cell wall

Answer 8

• Teichoic acids:
  ▪ Adhesion, induction of cytokines, resistance to host defences
• Peptidoglycan:
  ▪ Induction of cytokines
• Lipopolysaccharide:
  ▪ O-antigen: induction of cytokines and inflammatory response
  ▪ Resistance to host defences; adhesion
  ▪ Mediation of bone resorption and the killing of macrophages

Question 9

Describe the virulence factors in the flagellum

Answer 9

Motility, H-antigens, interaction with host cells

Question 10

Describe the virulence factors in the enzymes

Answer 10

• Proteases
• Collagenases
• Fibrinolysin, hyaluronidase, heprinase
• IgA and IgG proteases

Question 11

Whats the keystone pathogen concept

Answer 11

Periodontal disease is caused by communities of organisms working in concert, but some organisms may have a disproportionate influence on the pathogenicity of the community

Question 12

What are some examples of the keystone pathogen concept using P. gingivalis

Answer 12

P. gingivalis elevates the virulence of the entire community following interactive communication with accessory pathogens

Question 13

Describe Aggregatibacter Actinomycetemcomitans (Aa)

Answer 13

• Gram negative coccobacillus, anaerobic
• Associated with localised aggressive periodontitis
  o Associated with functional abnormalities
  o 6 serotypes - b is more common in aggressive patients
• Has a variety of virulence factors