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perio exam 1 > lecture 4- perio microbiology > Flashcards

lecture 4- perio microbiology Flashcards

1
Q

more than ______ distinct species of bacteria grow in the oral cavity

A

700

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2
Q

t/f: most oral microbial species have been cultured

A

false- 60% have never been cultured

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3
Q

what is the definition of a plaque biofilm?

A

organized cooperating community of organisms with specific inter-bacterial and host-bacterial interaction

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4
Q

the body develops ___________ to beneficial oral bacteria

A

immune-tolerance

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5
Q

what is Atopy? (AKA atopic dermatitis)

A
  • the “purell” disease
  • the body is not exposed to a variety of microorganisms early in life, and will start developing an immune response to its own cells
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6
Q

how many stages of biofilm formation are there?

A

5 stages

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7
Q

________ bacteria adhere to an acquired pellicle

A

planktonic

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8
Q

what 2 substances from human saliva are found in the pellicle

A
  • glycoproteins

- antibodies

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9
Q

how do “rapid attaching” bacteria attach to the pellicle

A

thru specific attachment structures

  • fimbriae
  • extracellular polymers
  • glycocalyx
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10
Q

how do bacterial characteristics change once they are attached to the pellicle?

A
  • synthesis of new outer membrane proteins

- active cellular growth

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11
Q

___________ found on bacteria are responsible for our bodies immune response

A

outer membrane proteins (OMP’s)

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12
Q

what is co-aggregation?

A

cell-to-cell recognition of genetically distinct cell types

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13
Q

what mediates co-aggregation

A

1) protein or glycoprotein receptors on one cell

2) carbohydrates on the other

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14
Q

what is co-aggregation influenced by?

A

temperature

lactose (more lactose, less aggregation)

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15
Q

t/f: cells co-aggregate once they attach to the pellicle

A

False

  • all cells are suspended when co-aggregating
  • “clumps” form, which then attach to pellicle
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16
Q

co-aggregation requires at least 2 of what?

A

2 genetically different species

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17
Q

what occurs during the maturation of the biofilm?

A
  • increase in diversity
  • replication and matrix formation
  • ecological succession
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18
Q

Porphyromonas gingivalis is a ______ colonizer. Is it gram negative or positive?

A

tertiary (3) colonizer

its gram negative

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19
Q

what are the 2nd colonizers also known as? are they usually gram negative or gram positive

A

bridge species

gram negative

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20
Q

F. nucleatum is known as a ______ colonizer

A

secondary (2) colonizer

AKA a bridge species

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21
Q

what is the role of F nucleatum in the biofilm?

A
  • its a “prolific co-aggregator”

- binds to other bacteria

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22
Q

name the most prolific primary (1st) colonizer. how does it bind a pellicle?

A
  • Streptococci species
  • bind pellicle proteins from saliva
  • primary colonizers can be either gram + or -
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23
Q

T/F: S. sanguis is found in large numbers in deep, active periodontal pockets

A

False- S sanguis is a beneficial species

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24
Q

T/F: through scaling and root planing of a deep periodontal pocket will most likely result in increased numbers of A. actinomycetemcomitans

A

false- A. a is a tertiary colonizer

cleaning would reduce the # of tertiary bacteria

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25
Q

name the tertiary, and harmful, microbes in the biofilm

A

1) A. actinomycetemcomitans
2) P. intermedia
3) Eubacterium species
4) T. denticola
5) P. gingivalis
6) S. flueggei

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26
Q

as the biofilm increases thickness, what occurs?

A
  • difficulty in diffusion in/out of the biofilm
  • an oxygen gradient develops
  • completely anaerobic conditions emerge in deep layers
  • reverse gradients of fermentation products develop as a result of bacterial metabolism
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27
Q

what is the nutritional source for supra gingival plaque?

A

dietary products dissolved in saliva

28
Q

_______ plaque feeds of periodontal tissues and blood

A

subgingival

29
Q

bacterial _____________ breakdown host macro-molecules into peptides and amino acids

A

hydrolytic enzymes

30
Q

micro-colonies make up about ____% of the biofilm volume

A

15-20%

31
Q

what are the 3 sources of the biofilm matrix?

A
  • dead bacterial cells (form scaffold)
  • saliva
  • gingival exudate
32
Q

what role do exopolysaccharides play in the biofilm?

A

they are the “backbone” of the biofilm

33
Q

what are the characteristics of the lower biofilm layers?

A
  • dense layer of microbes
  • polysaccharide matrix
  • tightly bound together
  • steep diffusion gradient
34
Q

the loose layer of the biofilm has what general characteristics?

A
  • irregular in appearance

- extends into surrounding medium

35
Q

what are the characteristics of the “fluid layer” of the biofilm?

A
  • stationary sublayer
  • fluid layer in motion
  • nourishes the biofilm by molecular diffusion
36
Q

cravicular epithelium will interact with the _______ layer of the biofilm

A

superficial

important for immune function/response

37
Q

the shape of micro-colonies depends on _______ force

A

shear

38
Q

if a micro-colony is in the form of towers or mushrooms, they are found in areas of _________

A

low shear force

39
Q

which type of colonies are capable of oscillation?

A

elongated colonies

found in areas of high shear

40
Q

the inter bacterial matrix of gram-positive bacteria is very ______. What causes this organization?

A

very fibrillar

-caused by dextrans and levans in the matrix

41
Q

the inter bacterial matrix of gram-negative bacteria is very ______. What causes this organization?

A

very regular

  • contains tri-laminar vesicles
  • Filled with endotoxins and proteolytic enzymes
42
Q

what type of inter bacterial matrix is filled with endotoxins and proteolytic enzymes?

A

gram-negative

43
Q

what roles do the inter bacterial carbohydrates of the matrix play?

A
  • energy source: dextrans, fructans

- skeleton of plaque- mutans

44
Q

the ______ forms the primary attachment in sub gingival plaque

A

cuticle

45
Q

how do the bacterial layers near the sulcular epithelium differ from tooth-attached layers? (in sub gingival plaque)

A
  • no inter-bacterial matrix

- more spirochetes and flagellated bacteria

46
Q

_____________ is necessary for succession

A

bacterial collaboration

47
Q

streptococcus cristatus is a _______ colonizer. what metabolic characteristics does this species have?

A

primary colonizer

  • can live with or without oxygen
  • uses up oxygen when available
48
Q

F. nucleatum is a _______ species. what are its metabolic characteristics?

A

bridge species

  • robust anaerobe
  • binding to strep improves survival when oxygen is present
49
Q

P. gingivalis is a ______ colonizer. what are its metabolic characteristics?

A

tertiary colonizer

  • microaerophilic, obligate anaerobe
  • coaggregation essential to survival when oxygen is present
50
Q

after coaggregation of bacteria in subgingival plaque, S. cristatus is carried into the gingiva by what other microbe?

A

S. cristatus is carried inside by F. nucleatum

51
Q

what are the defensive advantages for biofilm living?

A
  • presence of concentrated bacterial enzymes
  • inter-bacterial matrix

(these factors make the microbes harder to destroy)

52
Q

how are bacteria protected from external changes when living in a biofilm?

A
  • diffusion minimal in interior regions
  • antibiotic and antimicrobial resistance
  • protection from friction and shearing forces
  • attachment
53
Q

by what mechanisms can microbes transfer information and genetic mechanisms when living in the biofilm?

A
  • signaling (quorum sensing)
  • conjugation
  • transformation
  • plasmid transfer
  • transposon transfer
54
Q

what is quorum sensing?

A

regulation of expression of specific genes through accumulation of signaling compounds that mediate intercellular communication

55
Q

quorum sensing depends on cell ______

A

density

56
Q

t/f: quorum sensing encourages growth of beneficial species

A

true

57
Q

__________ produce AL-2 (a quorum sensing protein) in high levels

A

pathogens

58
Q

t/f: biofilm bacteria are less resistant to antibiotics than planktonic bacteria

A

false

biofilm bacteria are 1000 to 1500 times more resistant

59
Q

how does the slow growth rate of biofilm bacteria effect its sensitivity to antibiotics?

A
  • Antibiotics depend on cell turnover for efficacy
  • Slow-growers express ‘non-specific defense mechanisms’
  • Slow growers make more exo-polymers
60
Q

Exo-polymers retard _________

A

diffusion

important in biofilms ability to resist antibiotics

61
Q

what is involved in the ecological concept of oral microbial diseases?

A

Ecological shifts lead to changes in proportions

Balance shifts in favor of “pathogens”/disease

62
Q

t/f: Lack of competition in natural environments is a reason why growth of a microbe is different in nature
compared to pure culture.

A

false

63
Q

what is different between growing microbes in nature vs. growing them in pure cultures?

A

Limited nutrients in natural environments.

Poor nutrient distribution in natural environments.

Not optimal temperature in natural environments

64
Q

what are the clinical targets for therapy of microbes?

A

AI-2

Vaccines that target common resistance genes

65
Q

what is the clinical significance of Translocation and transmission of bacteria in the periodontal structures?

A
  • Periodontal probe can translocate pathogens from pockets to healthy sites
  • Drug-resistant strains can translocate to neighboring teeth
  • Teeth act as reservoirs for colonization of implants
66
Q

Implants that fail have a microbial composition similar to _____________

A

periodontal disease

67
Q

in regards to quarum sensing, ______ may determine switch from commensal to pathogenic community

A

AI-2

auto-inducer 2

perio exam 1 (8 decks)

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