LeMoual Flashcards
1
Q
Bacteria that predominates in the skin
A
actinobacteria
2
Q
Bacteria that predominates in the vagina
A
lactobacillus
3
Q
Bacteria that predominates in the gut (2)
A
Bacteroidetes and firmicutes
4
Q
Bacteria that predominates in the mouth
A
Streptococcus
5
Q
the most abundant genera in the oral cavity
A
streptococcus
6
Q
Most common type of strep found in the mouth
A
S. Mutans
7
Q
Bacteria which acts as an opportunistic pathogen and found in infective endocarditis
A
S. Oralis
8
Q
Strep that is beta hemolytic (3)
A
S. anginosus, S. intermedius, S constellatus
9
Q
Common O2 requirement of Strep
A
facultative anaerobe
10
Q
Define a-hemolytic
A
Incomplete hemolysis of red blood cells surrounding the colony that results in a greenish color
11
Q
Define B-hemolytic
A
Complete hemolysis of red blood cells surrounding the colony that results in clear appearance
12
Q
Bacteria found in perio pockets and implicated in juvy periodontitis
A
actinobacillus
13
Q
Major cause of dysbiosis
A
diet high in fermentable sugars
14
Q
Resident/normal microflora / Commensals/Symbionts
A
not patho, colonize a specific habitat
15
Q
transient microorganism
A
pass through the OC, do not colonize
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
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)
18
Q
Where are TLRs found? (2)
A
on the cell surface and in endosomes
19
Q
Where are NOD-like receptors found?
A
in the cytoplasm
20
Q
Activation of PRR.. (2)
A
- Promotes the innate immune responce
- nitiates the adaptive immune responce
21
Q
NOD1 senses
A
ie-DAP (produced by gram-)
22
Q
NOD2 senses
A
MDP (produced by all bacteria)
23
Q
density of resident bacteria in controlled by (2)
A
- IgAs
- antimicrobial peptides
24
Q
Most common organism in lips, tongue and cheek
A
facultative anearobe Strp (S. oralis)
25
Crypts and paillae of tongue have a ______ redox potential
low
26
Most type of organism in the tongue
obligate anearobe
27
bacteria in the supra gingival plaque will feed on
polyssacharides in the diet
28
gram- anaerobes in the subgingival plaque will feed on
proteins in the GCF
29
Physico-Chemical Factors that Influence the Oral Ecosystem (3)
1. Temp
2. pH
3. Redox potential
30
Important aciduric (acid-tolerant) species (2)
S. mutans and lactobacillus
31
Type of environment required by anaerobic bacteria
low Eh
32
Type of environment required by aerobic bacteria
high Eh
33
Nutrient gradient in plaque
more at the top
34
O2 gradient in plaque
more at the top
35
Eh gradient in plaque
more pos at the top
36
pH gradient in plaque
neutral at the top, more acidic at bottom (saliva neutralizes pH at the top
37
Metabolic product gradient in plaque
more at the bottom
38
main immunoglobulin in saliva
IgA
39
the flow of GCF ____ during inflammation
increases (problem since it feeds bacteria with proteins
40
main immunoglobulin in GCF
IgG
41
Role of IgA (2)
1. agglutinate bacteria and viruses
| 2. neutralize enzymes and toxins
42
Main families of anti-microbial peptides
1. Defencins a and B
2. Cathelicidins
3. Histatins
43
antimicrobial peptides synthesized by salivary glands
histatins`
44
antimicrobial peptides synthesized byepithelial cells (2)
defensins and cathelicidins
45
antimicrobial peptides have a net ____ charge
positive
46
Role of antimicrobial peptides (2)
1. Form pores that lyse bacterial cells
| 2. recruit neutrophils and produce cytokines
47
Structure of Cathelicidins
a-helical
48
Which AMP inhibit the development of Candida albicans from the non-infective to the infective form (hyphae)?
histatins (3 & 5)
49
Most abundant mucins in the human body (2)
Muc7 and Muc5B
50
Role of mucins in the OC
traps microorganisms and antigens, limiting their penetration into the tissues.
51
Common type of primary (initial) colonizers (2)
Strep (S. oralis, S sanguis and S. mitis but not S mutans) and Actinomyces
52
Bacterial adhesins are...
lectins (carbohydrate- binding proteins) that bind to carbohydrate receptors on a surface
53
Adhesin in gram- bacteria
FimH
54
Major fimbriae subunit in gram- bacteria
FimA
55
Chaperone fimbriae subunit in gram- bacteria
FimC (C=chaperone)
56
Usher fimbriae subunit in gram- bacteria
FimD
57
Non-fimbrial Adhesins are..
covalently attached to the cell wall (peptidoglycan)
58
Role pf Sortase on cell membrane
- 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
______ belong to the Streptococcus antigen I/II family of adhesins (2)
SspA and SspB
60
Ag I/II adhesins are present in (4)
1. S. mutans
2. S. gordonii
3. S. oralis
4. S. sanguinis
61
S. gordonii requires ____ to bind collagen
`SspA OR SspB adhesins
62
Pellicle contains (3)
protein, glycoportein, carbs
63
P. gingivalis major fimbriae (FimA) bind to (2)
- B2 integrins on macropahges
| - B1 integrins on gingival epithelial cells
64
Define Cryptitopes
Hidden receptors for bacterial adhesins
65
What can expose cryptitopes on host and bacterial
| proteins?
P gingivalis gingipain activity
66
The initial association of P. gingivalis with S. gordonii is mediated by...
the interaction of the major fimbriae (FimA) with GAPDH on the S. gordonii cell surface.
67
What induce signaling events within P. gingivalis that lead to phenotypic changes when in binds to S gordonii
Mfa1 (on P gingivalis) interactions with SspB (on S. gordonii)
68
Net result of P gingivalis interaction with S gordonii
Aherence of other P gingivalis to the first P gingivalis to form a microcolony
69
What is central to to the BAR domain of SspB interaction with Mfa?
the motif ExxP
70
What blocks the interaction of S gordonii and P gingivalis?
BAR peptid which binds to the BAR domain of SSpB on S. gordonii
71
Structure of biofilms
open structure with void spaces and water channels,which enable nutrients and oxygen to penetrate and circulate.
72
What is on the surafce P gingivalis? (2)
FimA and Mfa1
73
What is on the surafce S gordonii?
SspA/B and GAPDH
74
Mechanism of Resistance to Antibiotics in biofilms
1. slower rate of growth of bacteria
2. exopolysaccharide matrix of a biofim may have certain properties that can delay diffusion of antibiotics (charges)
2. Biosynthesis of extracellular enzymes (B-lactamase).
75
Quorum sensing signals in gram+
peptide auto-inducers (pheremones)
76
Role of response regulator proteins after activation by quorum sensing peptide in gram+
activate/repress transcription of specific target gene(s).
77
Quorum sensing signals in gram-
Acyl HSL
78
Extracellular quorum sensing peptides enter the cell by
interacting with membrane bound sensor kinase proteins which activate cognate response regulators.
79
Acyl HSL enters the cell by
diffusion
80
Upon reaching a critical concentration, the Acyl HSL is bound by
cognate LuxR-like protein that activates transcription of the target gene(s).
81
Precursor of AI-2 produced by many Gram- negative and Gram-positive bacteria
LuxS
82
How does LuxS become AL2
LuxS generates DPD that spontaneously cyclize in solution to form AI-2
83
Biofilm formation between Streptococcus oralis and Actinomyces naeslundi requires
AI-2 produced by S. oralis.
84
How does Veillonella reduce the cariogenic potential of S. mutans
It converts the lactate formed by S. mutans in the metabolism of carbs into a weaker acid (propionic acid
85
bacteriocins produced by S. mutans
mutacin
86
bacteriocins produced by S. Sanguis
Sanguicin
87
What bacteria produces H2O2 that kills S mutans?
S oligofermentans
88
How does S oligofermentans produce H2O2?
using lactate oxidase
89
early colonizers produce ______, which may enable them to evade the effects of secretory IgA.
IgA proteases
90
Growth rates of bacteria are fastest during this period
development of a confluent film of microorganisms
91
Where is the prevalence of caries is highest?
On occlusal surfaces (pits and fissures)
92
What causes demineralization of the enamel?
lactic acid, produced from the microbial fermentation of dietary carbohydrates.
93
EXAM: What is the critical pH is the demineralization of enamel?
5.5
94
EXAM: is the break down of hydroxyapatite into Ca and P reversible?
YES
95
What is fluoride's role?
Incorporates into hydroxyapatite (fluroapatite) which is less soluble that hydroxyapatite. Shifts reaction to the left.
96
Decalcification by acid from oral bacteria is dependent on (3)
1. Saliva flow
2. freq of sugar intake
3. exposure to fluroide
97
What is the most cariogenic sugar?
sucrose (because S mutans uses it preferentially)
98
4 factors required for dental caries to develop
1. Host
2. Presense of cariogenic bacteria
3. availability of carbs
3. time (18 mo)
99
Other than S mutans, what bacteria cause caries? (3)
Lactobacillus, Bifidobacterium dentium and low pH non-mutans streptococci
100
Common genera in caries
Veilonella
101
Why does C Albicans increase the risk of caries?
S mutans firmly adheres to it in the OC
102
EXAM Why is S mutans so bad? (2)
1. Very acidogenic
| 2. Very aciduric (survives at very low pH)
103
What is produced by S mutans that is responsible for plaque formation?
EPS
104
What is produced by S mutans that is allows acid production to continues in the absence of suagrs
IPS
105
What mutation in S mutans cause less cariogenicity? (4)
1. Production of glucans.
2. Production of lactic acid
3. Ability to cope with acidic pH.
106
Sucrose independant adhesion of S mutans involves
Antigen I/II in vitro (not a primary colonizer in vivo)
107
EXAM: Sucrose dependant adhesion of S mutans involves
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
Where are Glucosyltransferases found?`
Enamel pellicle or bind to bacterial surfaces (S. mutans or other bacteria)
109
Genes that encode glucosyltransferases (3)
gtfB/C/D
110
Metabolism of sucrose by SM (3)
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
three systems to transport carbohydrates within SM
1. PEP- phosphotransferase
2. multiple sugar metabolsim system
3. glucose permease
112
When sugar is in excess, what are the products of SM? (3)
formate, acetate and ethanol
113
How does SM live in high pH environments?
Uses ATP-synthase in the opposite direction to hyrolyse ATP and pump out protons
114
What is veillonella?
Gram-negative anaerobic coccus
115
S. gordoni inhibits the production of by ______ S. mutans.
bacteriocins
116
EXAM: What bacteria that possesses the enzyme urease transforms urea into ammonia and CO2
S. salivarius
117
Which species have the arginine dihydrolase system (ADS) which take arginine and catabolizes it into ornithine, ammonia and CO2 (2)
S. sanguis, S. gordonii
118
What is the affect of ammonia on caries?
Lowers the pH, which will prevent them from forming
119
Role of fluoride (3)
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
Main idea behind STAMPs
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
Immunotherapy of caries
use antibody against the the S. mutans adhesin antigen I/II
