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Microbiome > Lecture 11: Oral Microbiome in Disease > Flashcards

Lecture 11: Oral Microbiome in Disease Flashcards

1
Q

What are the most common oral diseases? and what are they both associated with?

A

Dental Caries & Periodontitis

-both associated with dental plaque

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2
Q

What are Dental Caries?

A

A disease of dental hard tissue characterized by demineralization of inorganic substance followed by breakdown of the organic matrix

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3
Q

In order for caries to develop what is required?

A

Need to Have: susceptible tooth, microorganisms which require a Substrate and need Time in order for caries to develop

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4
Q

What is the main substrate for bacteria in caries formation?

A

Sucrose

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5
Q

What is the Non-specific plaque hypothesis for Dental Caries?

A

they thought the entire mass of bacteria in dental plaque causes caries

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6
Q

What techniques were/are used to study the microbiology of dental caries?

A

Cultures, Closed-ended molecular techniques, and Open-ended molecular techniqes

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7
Q

What are the Close-ended molecular techniques?

A

PCR
DNA-DNA hybridization
Reverse Capture DNA-DNA hybridization
Microarrays (HOMIM)

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8
Q

What are the Open-ended Molecular Techniques?

A

16S rRNA sequencing
Whole metagenome sequencing
Whole metatranscriptome sequencing

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9
Q

What is the Specific Plaque Hypothesis for dental caries?

A

specific bacterial species in dental biofilm are capable of causing caries

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10
Q

What 4 groups have been implicated in dental caries?

A

Mutans streptococci
Lactobacilli
Actinomyces
Non-mutans streptococci

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11
Q

What are Mutans Streptococci’s role in dental caries?

A

The most important etiological agent of dental caries

-Initiation of coronal (crown) carious lesions

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12
Q

How many serotypes of mutans streptococci are there in humans?

A

8 (serotypes c, e, f, and K are most commonly associated with dental caries)

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13
Q

What do the cross-sectional and case control studies show about Mutans S. in relation to dental caries?

A

show that those who are affected have S. mutans at higher frequency than those who dont have dental caries (Strong Association with carious lesions)

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14
Q

What do the Risk Prediction (Longitudinal) studies show about Mutans S. in relation to dental caries

A

start with all healthy and then take samples of healthy individuals to see who has bacteria (exposed) and who doesn’t (not exposed), if we find out that those who are exposed have more dental caries as time passes then we can associate that species w/ caries
(A Determinant of Caries Risk)

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15
Q

What are S. mutans Virulence factors?

A 
Sugar fermentation into acids (acidogenic= acid production)
Acid Tolerance (acidouric)
Adhesion to tooth surface (sucrose dependent and Sucrose Independent)
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16
Q

What is Sucrose dependent binding process of S. mutans?

A

Glucosyltransferases break glucose into soluble and insoluble glucans,
The Insoluble glucans are used by bacteria to adhere to tooth surface S. mutans has glucan binding proteins

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17
Q

What is the Sucrose Independent binding process of S. mutans?

A

surface proteins meidates direct attachment to dental pellicle
SpaP (Ag I/II, AgB)-surface proteins

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18
Q

Whatis used as a source of energy for S. mutans?

A

Fructane (Fructosyltransferases breaksdown fructose to fructane)

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19
Q

What is Lactobacilli’s role in Dental Caries?

A

has low avidity for teeth; does not initiate carious lesions

Involved in the progression of dental caries after the caries formation has already been initiated by S. mutans

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20
Q

What are the predominatn Lactobacilli species found in the oral cavity in association w/ dental caries

A 
L. fermentum
L, gasseri
L rhamnosus
L. casie
L. paracasie
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21
Q

How is lactobacilli involved in the progression of dental caries but not in the initiation of caries?

A

Mutans S. starts the caries and that creates an environment w/ low pH and lactobacilli can attach and be apart of the progression of carious process

22
Q

What evidence is there that shows lactobacilli’s role in dental caries?

A

Strong association w/ deep carious lesions (cross-sectional and case-control studies)
Caries risk prediction (longitudinal/risk prediction studies)
Caries in experimental animals

23
Q

What are the virulence factors of Lactobacilli

A 
Highly acidogenic (production of acid)
Highly acidouric (can survive at lower pH than S. mutans can)
24
Q

What are some other species that have been found to be associated with dental caries?

A

Actinomyces: some evidence suggest role in root caries
-Non-mutans Streptococci: capable of producing acid at low pH and lowering pH below 4.4 (S, mitis, S.intermedius, and S. sanguinis

25
Q

What is the ecological hypothesis for dental caries?

A

we have pathogens in our normal flora in the oral cavity in low amounts-microbial homeostasis until we are subject to ecological pressures:
Frequent sugar intake–> increase acid production–> low pH–> changing ecology will cause microbial shift where there is increase in S. mutains causing the healthy enamel to have increase risk of caries as result

26
Q

What is C. albicans association with dental Caries and which bacteria does it synergize with?

A 
associated with early childhood caries 
capable of biofilm formation
Acidogenic
Acidouric
Synergizes with S. mutans
27
Q

What is the inter-kingdom interaction in dental caries?

A

C. albicans with S. mutans interactions

enhanced biofilm formation with both present this higher virulence for caries when together than alone

28
Q

What technique is used to determine what the microbial composition is?

A

16S rDNA approaches

29
Q

Metagenomics uses DNA sequences to determine what?

A

Determine what the genetic makeup is

30
Q

Metatranscriptomics use RNA to determine what?

A

Which genes are expressed

31
Q

Metaproteomics sequence proteins to determine what?

A

Determine the protein content

32
Q

Metaboiomics use metabolites to determine what?

A

the metabolic output

33
Q

What did omics technology find out about the microbiota associated with dental caries?

A 
Found it to be much more diverse  including the bacteria:
Scardovia wiggsiae
Veillonella 
Propionibacterium
Bifidobacterium
Actinomyces 
Atopobium
34
Q

What bacteria is associated with dental caries, particularly early childhood caries? and what are its virulence factors?

A 
Scardovia wiggsiae
frequently co-exist with S. mutans
Acidogenic
Acidouric
but failed to induce caries in experimental animals
35
Q

What 3 enzymes were found to be really abundant in health when using Whole Genomic Sequencing?

A

arginase Deiminase
thyeronine ammonia lysase
dCTP Deiminase

36
Q

What role doses Deiminases have in Dental Caries?

A

can produce ammonium which helps to neutralize the acidic environment

37
Q

Which bacteria are associated with root caries as shown by HOMIM study?

A 
L. casie
P. alactolyticus
S. oralis
S. parassanguinis/ BE024
D. pneumosintes
38
Q

Have molecular techniques provided evidence for the involvement of actinomyces with dental caries?

A

No, molecular techniques have Not shown evidence for actinomyces w/ caries

39
Q

Currently, what is the conclusion on how dental caries develop?

A

caries are thought to be caused by dysbiosis in response to an ecological stress resulting in:

  • altered microbial community composition & function
  • imbalanced metabolic activity
40
Q

What is Periodontitis?

A

A chronic infection of the tooth supporting structures, the periodontium, characterized by progressive bone loss and soft tissue damage

41
Q

What are the 4 groups of microorganisms that were thought to be involved in Periodontitis?

A

Ameobe
Spirochetes
Fusiforms
Streptococci

42
Q

What was the Non-specific plaque hypothesis in periodontitis?

A

increase in bacterial plaque mass triggers periodontits?

43
Q

Are there more facultative or anerobic microorgansims in periodontitis?

A

Lots of anaerobic (gram -) bacteria

44
Q

What are the criteria for defining periodontal pathogens?

A

Association: species found more frequently & in much higher numbers in the cases of disease
Elimination: of species is accompanied by a parallel remission of disease
Host Response: elevated serum or salivary antibodies against the putative pathogen
Possession of virulence factors
Induce destruction in animal models
Risk Assessment (longitudinal studies)

45
Q

What species is associated with aggressive periodontitis? (localized form)

A

A. actinomycetemcomitans

46
Q

What complex is Strongly associated with chronic periodontitis?

A

Red Complex

47
Q

Which complex is Moderately associated with Chronic Periodontitis?

A

Orange complex

48
Q

What is the ecological plaque hypothesis for periodontitis?

A

more plaque accumulation–> increased inflammation–> increase GCF flow and slightly higher pH and slightly lower temp can result n ecological shift from predominately gram + microflora to predominately Gram - microflora associated with periodontitis
this happens when subject to ecological pressure

49
Q

What new putative pathogens were identified by the use of open-ended DNA sequencing techniques?

A

TM7
Oral synergistetes
Filifactor alocis
All anerobes

50
Q

What is the keystone pathogen-microbial dysbiosis hypothesis?

A

Introduce P. gingivalis (keystone pathogen) and its subversion of immune response of inflammation and causes changes in the microbial community to dysbiosis which in turn induces disease (periodontitis)

51
Q

What are today’s current conclusions on the microbiology of periodontitis?

A

A keystone pathogen that by subverting the immune response triggers a microbial dysbiosis characterized by:

  • altered microbial community composition
  • altered microbial community function

Microbiome (6 decks)

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