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Dent 203 > LeMoual > Flashcards

LeMoual Flashcards

1
Q

Bacteria that predominates in the skin

A

actinobacteria

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2
Q

Bacteria that predominates in the vagina

A

lactobacillus

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3
Q

Bacteria that predominates in the gut (2)

A

Bacteroidetes and firmicutes

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4
Q

Bacteria that predominates in the mouth

A

Streptococcus

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5
Q

the most abundant genera in the oral cavity

A

streptococcus

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6
Q

Most common type of strep found in the mouth

A

S. Mutans

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7
Q

Bacteria which acts as an opportunistic pathogen and found in infective endocarditis

A

S. Oralis

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8
Q

Strep that is beta hemolytic (3)

A

S. anginosus, S. intermedius, S constellatus

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9
Q

Common O2 requirement of Strep

A

facultative anaerobe

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10
Q

Define a-hemolytic

A

Incomplete hemolysis of red blood cells surrounding the colony that results in a greenish color

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11
Q

Define B-hemolytic

A

Complete hemolysis of red blood cells surrounding the colony that results in clear appearance

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12
Q

Bacteria found in perio pockets and implicated in juvy periodontitis

A

actinobacillus

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13
Q

Major cause of dysbiosis

A

diet high in fermentable sugars

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14
Q

Resident/normal microflora / Commensals/Symbionts

A

not patho, colonize a specific habitat

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15
Q

transient microorganism

A

pass through the OC, do not colonize

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16
Q

Explain surface inhibition

A

resident microflora will occupy all the receptors sites in a given habitat, does not allow pathogenic flora to adhere and allows them to be cleared away

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17
Q

Propeties of resident microflora that contributes to pathogenic colonization resistance (4)

A

competition for receptor sites
competition for nutrients
creation of micro-environment that prevent growth of patho organism
production of inhibitory factors (bacteriocins)

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18
Q

Where are TLRs found? (2)

A

on the cell surface and in endosomes

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19
Q

Where are NOD-like receptors found?

A

in the cytoplasm

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20
Q

Activation of PRR.. (2)

A
  • Promotes the innate immune responce

- nitiates the adaptive immune responce

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21
Q

NOD1 senses

A

ie-DAP (produced by gram-)

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22
Q

NOD2 senses

A

MDP (produced by all bacteria)

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23
Q

density of resident bacteria in controlled by (2)

A
  • IgAs

- antimicrobial peptides

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24
Q

Most common organism in lips, tongue and cheek

A

facultative anearobe Strp (S. oralis)

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25
Q

Crypts and paillae of tongue have a ______ redox potential

A

low

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26
Q

Most type of organism in the tongue

A

obligate anearobe

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27
Q

bacteria in the supra gingival plaque will feed on

A

polyssacharides in the diet

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28
Q

gram- anaerobes in the subgingival plaque will feed on

A

proteins in the GCF

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29
Q

Physico-Chemical Factors that Influence the Oral Ecosystem (3)

A
  1. Temp
  2. pH
  3. Redox potential
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30
Q

Important aciduric (acid-tolerant) species (2)

A

S. mutans and lactobacillus

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31
Q

Type of environment required by anaerobic bacteria

A

low Eh

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32
Q

Type of environment required by aerobic bacteria

A

high Eh

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33
Q

Nutrient gradient in plaque

A

more at the top

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34
Q

O2 gradient in plaque

A

more at the top

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35
Q

Eh gradient in plaque

A

more pos at the top

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36
Q

pH gradient in plaque

A

neutral at the top, more acidic at bottom (saliva neutralizes pH at the top

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37
Q

Metabolic product gradient in plaque

A

more at the bottom

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38
Q

main immunoglobulin in saliva

A

IgA

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39
Q

the flow of GCF ____ during inflammation

A

increases (problem since it feeds bacteria with proteins

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40
Q

main immunoglobulin in GCF

A

IgG

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41
Q

Role of IgA (2)

A
  1. agglutinate bacteria and viruses

2. neutralize enzymes and toxins

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42
Q

Main families of anti-microbial peptides

A
  1. Defencins a and B
  2. Cathelicidins
  3. Histatins
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43
Q

antimicrobial peptides synthesized by salivary glands

A

histatins`

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44
Q

antimicrobial peptides synthesized byepithelial cells (2)

A

defensins and cathelicidins

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45
Q

antimicrobial peptides have a net ____ charge

A

positive

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46
Q

Role of antimicrobial peptides (2)

A
  1. Form pores that lyse bacterial cells

2. recruit neutrophils and produce cytokines

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47
Q

Structure of Cathelicidins

A

a-helical

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48
Q

Which AMP inhibit the development of Candida albicans from the non-infective to the infective form (hyphae)?

A

histatins (3 & 5)

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49
Q

Most abundant mucins in the human body (2)

A

Muc7 and Muc5B

50
Q

Role of mucins in the OC

A

traps microorganisms and antigens, limiting their penetration into the tissues.

51
Q

Common type of primary (initial) colonizers (2)

A

Strep (S. oralis, S sanguis and S. mitis but not S mutans) and Actinomyces

52
Q

Bacterial adhesins are…

A

lectins (carbohydrate- binding proteins) that bind to carbohydrate receptors on a surface

53
Q

Adhesin in gram- bacteria

A

FimH

54
Q

Major fimbriae subunit in gram- bacteria

A

FimA

55
Q

Chaperone fimbriae subunit in gram- bacteria

A

FimC (C=chaperone)

56
Q

Usher fimbriae subunit in gram- bacteria

A

FimD

57
Q

Non-fimbrial Adhesins are..

A

covalently attached to the cell wall (peptidoglycan)

58
Q

Role pf Sortase on cell membrane

A
  • recognizes the LPXTG motif and cleaves the protein between the threonine and the glycine residues.
  • catalyzes the formation of an amide bond between the surface protein and the NH2-terminal of the pentaglycine of Lipid II.
59
Q

______ belong to the Streptococcus antigen I/II family of adhesins (2)

A

SspA and SspB

60
Q

Ag I/II adhesins are present in (4)

A
  1. S. mutans
  2. S. gordonii
  3. S. oralis
  4. S. sanguinis
61
Q

S. gordonii requires ____ to bind collagen

A

`SspA OR SspB adhesins

62
Q

Pellicle contains (3)

A

protein, glycoportein, carbs

63
Q

P. gingivalis major fimbriae (FimA) bind to (2)

A
  • B2 integrins on macropahges

- B1 integrins on gingival epithelial cells

64
Q

Define Cryptitopes

A

Hidden receptors for bacterial adhesins

65
Q

What can expose cryptitopes on host and bacterial

proteins?

A

P gingivalis gingipain activity

66
Q

The initial association of P. gingivalis with S. gordonii is mediated by…

A

the interaction of the major fimbriae (FimA) with GAPDH on the S. gordonii cell surface.

67
Q

What induce signaling events within P. gingivalis that lead to phenotypic changes when in binds to S gordonii

A

Mfa1 (on P gingivalis) interactions with SspB (on S. gordonii)

68
Q

Net result of P gingivalis interaction with S gordonii

A

Aherence of other P gingivalis to the first P gingivalis to form a microcolony

69
Q

What is central to to the BAR domain of SspB interaction with Mfa?

A

the motif ExxP

70
Q

What blocks the interaction of S gordonii and P gingivalis?

A

BAR peptid which binds to the BAR domain of SSpB on S. gordonii

71
Q

Structure of biofilms

A

open structure with void spaces and water channels,which enable nutrients and oxygen to penetrate and circulate.

72
Q

What is on the surafce P gingivalis? (2)

A

FimA and Mfa1

73
Q

What is on the surafce S gordonii?

A

SspA/B and GAPDH

74
Q

Mechanism of Resistance to Antibiotics in biofilms

A
  1. slower rate of growth of bacteria
  2. exopolysaccharide matrix of a biofim may have certain properties that can delay diffusion of antibiotics (charges)
  3. Biosynthesis of extracellular enzymes (B-lactamase).
75
Q

Quorum sensing signals in gram+

A

peptide auto-inducers (pheremones)

76
Q

Role of response regulator proteins after activation by quorum sensing peptide in gram+

A

activate/repress transcription of specific target gene(s).

77
Q

Quorum sensing signals in gram-

A

Acyl HSL

78
Q

Extracellular quorum sensing peptides enter the cell by

A

interacting with membrane bound sensor kinase proteins which activate cognate response regulators.

79
Q

Acyl HSL enters the cell by

A

diffusion

80
Q

Upon reaching a critical concentration, the Acyl HSL is bound by

A

cognate LuxR-like protein that activates transcription of the target gene(s).

81
Q

Precursor of AI-2 produced by many Gram- negative and Gram-positive bacteria

A

LuxS

82
Q

How does LuxS become AL2

A

LuxS generates DPD that spontaneously cyclize in solution to form AI-2

83
Q

Biofilm formation between Streptococcus oralis and Actinomyces naeslundi requires

A

AI-2 produced by S. oralis.

84
Q

How does Veillonella reduce the cariogenic potential of S. mutans

A

It converts the lactate formed by S. mutans in the metabolism of carbs into a weaker acid (propionic acid

85
Q

bacteriocins produced by S. mutans

A

mutacin

86
Q

bacteriocins produced by S. Sanguis

A

Sanguicin

87
Q

What bacteria produces H2O2 that kills S mutans?

A

S oligofermentans

88
Q

How does S oligofermentans produce H2O2?

A

using lactate oxidase

89
Q

early colonizers produce ______, which may enable them to evade the effects of secretory IgA.

A

IgA proteases

90
Q

Growth rates of bacteria are fastest during this period

A

development of a confluent film of microorganisms

91
Q

Where is the prevalence of caries is highest?

A

On occlusal surfaces (pits and fissures)

92
Q

What causes demineralization of the enamel?

A

lactic acid, produced from the microbial fermentation of dietary carbohydrates.

93
Q

EXAM: What is the critical pH is the demineralization of enamel?

A

5.5

94
Q

EXAM: is the break down of hydroxyapatite into Ca and P reversible?

A

YES

95
Q

What is fluoride’s role?

A

Incorporates into hydroxyapatite (fluroapatite) which is less soluble that hydroxyapatite. Shifts reaction to the left.

96
Q

Decalcification by acid from oral bacteria is dependent on (3)

A
  1. Saliva flow
  2. freq of sugar intake
  3. exposure to fluroide
97
Q

What is the most cariogenic sugar?

A

sucrose (because S mutans uses it preferentially)

98
Q

4 factors required for dental caries to develop

A
  1. Host
  2. Presense of cariogenic bacteria
  3. availability of carbs
  4. time (18 mo)
99
Q

Other than S mutans, what bacteria cause caries? (3)

A

Lactobacillus, Bifidobacterium dentium and low pH non-mutans streptococci

100
Q

Common genera in caries

A

Veilonella

101
Q

Why does C Albicans increase the risk of caries?

A

S mutans firmly adheres to it in the OC

102
Q

EXAM Why is S mutans so bad? (2)

A
  1. Very acidogenic

2. Very aciduric (survives at very low pH)

103
Q

What is produced by S mutans that is responsible for plaque formation?

A

EPS

104
Q

What is produced by S mutans that is allows acid production to continues in the absence of suagrs

A

IPS

105
Q

What mutation in S mutans cause less cariogenicity? (4)

A
  1. Production of glucans.
  2. Production of lactic acid
  3. Ability to cope with acidic pH.
106
Q

Sucrose independant adhesion of S mutans involves

A

Antigen I/II in vitro (not a primary colonizer in vivo)

107
Q

EXAM: Sucrose dependant adhesion of S mutans involves

A
  1. Takes sucrose and break it down into glucose and fructose
  2. use glucose to make glucan polymers by glucosyltransferase
  3. glucan binding protein on SM binds to the glucan in the ECM
108
Q

Where are Glucosyltransferases found?`

A

Enamel pellicle or bind to bacterial surfaces (S. mutans or other bacteria)

109
Q

Genes that encode glucosyltransferases (3)

A

gtfB/C/D

110
Q

Metabolism of sucrose by SM (3)

A
  1. cleaved extracellularly by bacterial invertases and fru/glu imported into the bacteria
  2. Transported inside the cell and then cleaved by invertase or sucrose phosphate hydrolase
  3. used extracellularly by glucosyltransferases to make glucans or by fructosyltransferases to make fructans
111
Q

three systems to transport carbohydrates within SM

A
  1. PEP- phosphotransferase
  2. multiple sugar metabolsim system
  3. glucose permease
112
Q

When sugar is in excess, what are the products of SM? (3)

A

formate, acetate and ethanol

113
Q

How does SM live in high pH environments?

A

Uses ATP-synthase in the opposite direction to hyrolyse ATP and pump out protons

114
Q

What is veillonella?

A

Gram-negative anaerobic coccus

115
Q

S. gordoni inhibits the production of by ______ S. mutans.

A

bacteriocins

116
Q

EXAM: What bacteria that possesses the enzyme urease transforms urea into ammonia and CO2

A

S. salivarius

117
Q

Which species have the arginine dihydrolase system (ADS) which take arginine and catabolizes it into ornithine, ammonia and CO2 (2)

A

S. sanguis, S. gordonii

118
Q

What is the affect of ammonia on caries?

A

Lowers the pH, which will prevent them from forming

119
Q

Role of fluoride (3)

A
  1. inhibits the production of intracellular glycogen (IPS).
  2. Reduces glycolysis rate by inhibiting enolase.
  3. Inhibits sugar transport by decreasing the amount of PEP generated (PEP is necessary for sugar transport by PTS system).
120
Q

Main idea behind STAMPs

A

Take a targeting peptide (the quorum sensing peptide CSP in S mutans) and attach to it an antimicrobial peptide]
- allows you to specifically target SM

121
Q

Immunotherapy of caries

A

use antibody against the the S. mutans adhesin antigen I/II

Dent 203 (2 decks)

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