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microbiology of periodontal disease > Periodontal Microbiology #4 > Flashcards

Periodontal Microbiology #4 Flashcards

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Biology 101 flashcards
1
Q

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

A

14 days

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2
Q

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

A

700 (most individuals has about 60)

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3
Q

What is a plaque biofilm?

A

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

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4
Q

Is gingivitis only bacteria induced?

A

NO! viruses and fungi have been implicated too

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5
Q

You remove ____% of plaque when you brush?

A

40

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6
Q

What are the stages of plaque formation?

A 
Pelllicle formation? 
Attachement
Growth
Maturation
Ecological succession
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7
Q

What is the difference between rapid and slow attachers?

A
  • Rapid have specialized methods of attachment structures (fimbriae)
  • Slow attachers have no specific mechanism for attachment.
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8
Q

When does co-aggregation and co-adhesion occur?

A

During the growth stage!

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9
Q

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

A

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

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10
Q

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

A

Co-adhesion

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11
Q

What factors influence Co-adhesion?

A

Increase in Lactose = decrease in co-adhesion

Temperature = no co-adhesion greater than 37 degrees

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12
Q

What is the purpose of Co-aggregation?

A

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.

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13
Q

Describe what happens during the Maturation stage of biofilm formation.

A
  • Increase in diversity
  • Replication and matrix formation
  • Ecological succession
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14
Q

What types of bacteria are Primary or Early colonizers?

A

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

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15
Q

What Types of bacteria are Secondary colonizers?

A

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

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16
Q

What types of bacteria are Tertiary colonizers?

A

Gram negative bacteria (prophromonas gingivalis)

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17
Q

What occurs environmentally when the biofilm increases in thickness?

A
  • 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.
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18
Q

What is the nutritional source for supra gingival plaque?

A

Dietary products dissolved in saliva

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19
Q

What is the nutritional source for sub gingival plaque?

A

Blood and Periodontal tissues

20
Q

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

A

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

21
Q

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

A
  • Dead bacterial cells
  • Saliva
  • Gingival exudate
22
Q

_______ are considered the backbone of the biofilm.

A

Exopolysaccharides

23
Q

What are the 3 layers of a biofilm?

A
  • Lower layer = dense layer of microbes w/ steep concentration gradient.
  • Loose layer
  • Fluid layer = nourishes the biofilm by molecular diffusion
24
Q

How does the physical structure of plaque differ?

A

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.
25
Q

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

A

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
26
Q

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

A

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.

27
Q

Which level of colonizers illicit the most immune response?

A

Tertiary colonizers

28
Q

Bacterial collaboration is necessary for ________.

A

Succession

29
Q

What kind of environment does Streptococcus Cristatus need?

A
  • Facultative species (can live with or without O2)

- Uses up O2 when available

30
Q

What kind of environment does Fusobacterium nucleatum need?

A
  • Robust ANEROBE

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

31
Q

What kind of environment does Porphyromonas gingivalis need?

A
  • Microareophilic, obligate anaerobe

- Coaggregation essential to survival when O2 is present

32
Q

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

A

Good to know

33
Q

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

A
  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…..
34
Q

What is Quorum sensing?

A

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

35
Q

What are the benefits of Quorum sensing?

A
  • Antibiotic resistance in dense biofilms

- encourages growth of beneficial species

36
Q

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

A

Low

37
Q

_______ produces Al-2 in high levels.

A

Pathogens

38
Q

______ may determine the switch from commensal to pathogenic community.

A

Al-2 presence

39
Q

Antibiotics depend on _____ for efficacy.

A

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

40
Q

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

A

1000-1500 times more resistant

41
Q

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

A

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

42
Q

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

A

It increases antibiotic resistance

43
Q

What is the Classic concept of a pathogen?

A
  • Not normally present

- Produce virulence factors (damage to host)

44
Q

Do oral pathogens fit the classic concept?

A

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

45
Q

_______ leads to changes in “pathogen” proportions

A

Ecological shifts

46
Q

Can perio probing translocate bacteria?

A

Absolutely

microbiology of periodontal disease (3 decks)

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