Periodontal Microbiology #4

Question 1

Roughy how long does it take (without brushing) for the average person to get gingivitis?

Answer 1

14 days

Question 2

There are more than ______ species of bacteria found in the mouth.

Answer 2

700 (most individuals has about 60)

Question 3

What is a plaque biofilm?

Answer 3

Organized cooperating community of organisms with specific inter-bacterial and host-bacterial interactions. (not just one type of bacteria)

Question 4

Is gingivitis only bacteria induced?

Answer 4

NO! viruses and fungi have been implicated too

Question 5

You remove ____% of plaque when you brush?

Answer 5

40

Question 6

What are the stages of plaque formation?

Answer 6

Pelllicle formation? 
Attachement
Growth
Maturation
Ecological succession

Question 7

What is the difference between rapid and slow attachers?

Answer 7

• Rapid have specialized methods of attachment structures (fimbriae)
• Slow attachers have no specific mechanism for attachment.

Question 8

When does co-aggregation and co-adhesion occur?

Answer 8

During the growth stage!

Question 9

_____ is cell-to-cell recognition of genetically distinct/different cell types.

Answer 9

Co-aggregation ** This is mediated by protein or glycoprotein receptors on one cell and carbohydrates on the other.

Question 10

_____ is the interactions between suspended and already adhering micro-organisms.

Answer 10

Co-adhesion

Question 11

What factors influence Co-adhesion?

Answer 11

Increase in Lactose = decrease in co-adhesion

Temperature = no co-adhesion greater than 37 degrees

Question 12

What is the purpose of Co-aggregation?

Answer 12

To form clumps of bacteria that can attach to the pellicle.

* This is mediated by protein or glycoprotein receptors on one cell and carbohydrates on the other.

Question 13

Describe what happens during the Maturation stage of biofilm formation.

Answer 13

• Increase in diversity
• Replication and matrix formation
• Ecological succession

Question 14

What types of bacteria are Primary or Early colonizers?

Answer 14

Gram + and Gram -
Streptococci bind pellicle proteins from saliva
*Primary colonizers are associated with health!

Question 15

What Types of bacteria are Secondary colonizers?

Answer 15

Gram Negative bridge species (F. Nucleatum Prolific coaggregator) bind to other bacteria

Question 16

What types of bacteria are Tertiary colonizers?

Answer 16

Gram negative bacteria (prophromonas gingivalis)

Question 17

What occurs environmentally when the biofilm increases in thickness?

Answer 17

• Difficulty in diffusion join and out of the biofilm
• An oxygen gradient develops
• Completely anaerobic (no oxygen) conditions emerge in the deeper layers which can lead to fermentation.
• Reverse gradients of fermentation products develop as a result of bacterial metabolism.

Question 18

What is the nutritional source for supra gingival plaque?

Answer 18

Dietary products dissolved in saliva

Question 19

What is the nutritional source for sub gingival plaque?

Answer 19

Blood and Periodontal tissues

Question 20

The structure of the biofilm can be described as ________ + _________.

Answer 20

Micro-colonies (15-20% volume) + inter-bacterial matrix

Question 21

What makes up the inter-bacterial matrix of the biofilm?

Answer 21

• Dead bacterial cells
• Saliva
• Gingival exudate

Question 22

_______ are considered the backbone of the biofilm.

Answer 22

Exopolysaccharides

Question 23

What are the 3 layers of a biofilm?

Answer 23

• Lower layer = dense layer of microbes w/ steep concentration gradient.
• Loose layer
• Fluid layer = nourishes the biofilm by molecular diffusion

Question 24

How does the physical structure of plaque differ?

Answer 24

Shape of colonies depend on shear force exposure.

• Interproximal (Supra gingival) = towers or mushrooms due to low shear force.
• Buccal side of teeth (supra) = elongated colonies capable of oscillation and withstanding high shear force.
• Subgingival plaque is similar to supragingival plaque in structure.

Question 25

Describe the Structure of the inter-bacterial matrix of plaque…

Answer 25

It is highly variable…

• Gram + matrix is very fibrillar due to dextran and levans.
• Gram Negative matrix is very regular (Increases in health!), contains trilaminar vesicles filled with endotoxins and proteolytic enzymes.
• Inter-bacterial carbohydrates = energy source for dextran and fructans. *also skeleton of plaque

Question 26

What is the main differences in structure between supra gingival plaque and subgingival plaque?

Answer 26

Sub gingival = cuticle forms primary attachment
*Bacterial layers near surface epithelium are different from tooth attached plaque (No inter-bacterial matrix and have more spirochetes and flagellated bacteria)

Supra gingival = plaque is attached by salivary pellicle.

Question 27

Which level of colonizers illicit the most immune response?

Answer 27

Tertiary colonizers

Question 28

Bacterial collaboration is necessary for ________.

Answer 28

Succession

Question 29

What kind of environment does Streptococcus Cristatus need?

Answer 29

• Facultative species (can live with or without O2)

- Uses up O2 when available

Question 30

What kind of environment does Fusobacterium nucleatum need?

Answer 30

• Robust ANEROBE

- Binding to Strep improves survival when O2 is present (Example of Bacterial collaboration)

Question 31

What kind of environment does Porphyromonas gingivalis need?

Answer 31

• Microareophilic, obligate anaerobe

- Coaggregation essential to survival when O2 is present

Question 32

Strep, Fuso and Porphyro form a robust biofilm in the presence of O2.

Answer 32

Good to know

Question 33

What are the 3 main advantages for bacteria as part of a biofilm?

Answer 33

1. Defense = concentrated bacterial enzymes
2. Protection = from friction, antibiotics, and diffusion is limited in interior regions.
3. Transfer of info and genetic material = signaling, conjugation…..

Question 34

What is Quorum sensing?

Answer 34

Regulation of expression of specific genes through accumulation of signaling compounds that mediate intercellular communications.

Question 35

What are the benefits of Quorum sensing?

Answer 35

• Antibiotic resistance in dense biofilms

- encourages growth of beneficial species

Question 36

Commensal bacterial produce and respond to _____ levels of Al-2.

Answer 36

Low

Question 37

_______ produces Al-2 in high levels.

Answer 37

Pathogens

Question 38

______ may determine the switch from commensal to pathogenic community.

Answer 38

Al-2 presence

Question 39

Antibiotics depend on _____ for efficacy.

Answer 39

Cell turnover *Important b/c antibiotic resistant bacteria usually have slow turnover rates.

Question 40

Biofilm bacteria are ______ time more resistant than the planktonic variety.

Answer 40

1000-1500 times more resistant

Question 41

What do Exo-polymers do in regards to antibiotic resistance?

Answer 41

They retard diffusion of antibiotic *slow growing bacteria make Exo-polymers.

Question 42

What is the significance of the fact that biofilms express different genes?

Answer 42

It increases antibiotic resistance

Question 43

What is the Classic concept of a pathogen?

Answer 43

• Not normally present

- Produce virulence factors (damage to host)

Question 44

Do oral pathogens fit the classic concept?

Answer 44

No, b/c they are normally present through out life and damage usually requires large numbers

Question 45

_______ leads to changes in “pathogen” proportions

Answer 45

Ecological shifts

Question 46

Can perio probing translocate bacteria?

Answer 46

Absolutely