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BDS3 Caries Symposium > Caries Microbiology > Flashcards

Caries Microbiology Flashcards

1
Q

What is colonisation?

A
  • When microbes find a new host and start to multiply
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2
Q

What is normal flora?

A
  • A balance can develop between colonised microbes and humans - will lead to ‘so called’ normal flora
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3
Q

If microbes cause disease what is this called?

A
  • An infection
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4
Q

What is an endogenous infection?

A
  • If source of microbe is patients own flora
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5
Q

What is an exogenous infection?

A
  • IF the source of microbe is flora from outside the patients body
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6
Q

What is dental plaque?

A
  • A diverse microbial community (predominantly bacteria) found on the tooth surface, embedded in a matrix of polymers of bacterial and salivary origin
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7
Q

What is the main aetiological agent associated with caries?

A
  • Plaque
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8
Q

The oral microbiome is predominantly found on hard tissues. Where else can it be found? (2)

A
  • Also found on dorsum of tongue

- Can be found on soft tissues (shedding)

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9
Q

We are sterile at birth, so where so we get bacterial species from? (4)

A
  • Food
  • Milk
  • Water
  • Mothers Saliva
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10
Q

What are the 4 stages of plaque development?

A
  • Colonisation by pioneer bacteria
  • Outcrowth
  • Secondary colonisation
  • Climax community
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11
Q

What are the basic concepts of oral microbiology? (5)

A
  • A wide variety of microbes regularly enter the oral cavity
  • Saliva, pH, temperature, immune system prevent many species from surviving
  • Brushing and flossing teeth clears some built up biofilm
  • Oral antibiotics inhibit growth
  • Symbiosis of the oral microbes that are able to survive these conditions form an elaborate scaffold that lived on the tooth enamel and at the interface with the gums. It forms a barrier for incoming bacteria
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12
Q

What is caries?

A
  • Loss of mineralised surfaces of the tooth
  • Surface are permanently damaged by the microbial plaque
  • Underlying dentine is at risk, or damaged
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13
Q

Caries is a multi-factorial disease. What are 2 main factors?

A
  • Microbial biofilms

- Acidity: sugar metabolism

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14
Q

What are the characteristic for a low caries risk person? (4)

A
  • Alkalia producing bacteria such as S. sanguinis
  • Unstimulated saliva flow of >1ml/min
  • Infrequent sucrose consumption
  • Fluoride intake to levels allowing production of fluorapatite
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15
Q

What are the characteristics for a high caries risk person? (4)

A
  • Acid prodcing bacteria such as mutans streptococci and lactobacilli
  • Unstimulated saliva flow of <0.7ml/min
  • Frequent consumption of high levels of sucrose and other fermentable carbohydrates
  • Little or no fluoride intake
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16
Q

What is involved in the process of caries progression? (6)

A
  • Adhesion
  • Survival & growth
  • Biofilm formation
  • Complex plaque
  • Acid
  • Caries
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17
Q

What are the key cariogenic pathogens? (5)

A
  • Streptococcus mutans
  • Lactobacillus acidophilus
  • Actinomyces Viscous
  • Candida albicans
  • Nocardia spp.
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18
Q

What is the factor that drives demineralisation?

A
  • Microbial metabolism
19
Q

What is the role of Pili on a bacterial cell?

A
  • Help attach
20
Q

What is the role of the capsule on a bacterial cell?

A
  • Sticky and helps to evade the immune system
21
Q

What is the role of Flagella on a bacterial cell?

A
  • To help swim through saliva
22
Q

What are caries associations with S. mutans? (long answer - learn it)

A

FACTORS RELATED TO CARIOGENICITY OF STREPTOCOCCUS MUTANS

• Significant correlations in humans between S mutans counts in saliva and

plaque with the prevalence and incidence of caries

• S. mutans can be isolated from precise sites on the tooth surface before the

development of caries

  • Correlation between the progression of carious lesions and S mutans counts
  • Produces water-soluble and insoluble extracellular polysaccharides from sucrose

which help in the colonization of tooth surfaces by consolidating microbial

attachment

• Most effective streptococcus in experimental caries in animals (rodents and

non-human primates)

• Ability to initiate and maintain microbial growth and to continue acid production

in sites with a low pH

  • Rapid metabolism of sugars to lactic and other organic acids
  • Can attain the critical pH for enamel demineralization more rapidly than other

common plaque bacteria

• Produces intracellular polysaccharide which can act as a food store for use when

dietary carbohydrate is low

• Immunisation of animals with S mutans significantly reduces the incidence of

caries

23
Q

What is included in Koch’s Postulates: The Germ Theory Of Disease? (4)

A
  • The microbe must be present in ever care of the disease
  • The microbe must be isolated from the diseased host and grown in pure culture
  • The disease must be reproduces when a pure culture is introduces into a susceptible host
  • The microbe must be recovered from an experimentally infected host
24
Q

What kind of micro-organism is streptococcus mutans?

A
  • Gram positive coccus
25
Q

How many serotypes are there of streptococcus mutans?

A
  • 8 serotypes
26
Q

What are streptococcus mutans good at?

A
  • Good at adhesion and biofilm formation
27
Q

Streptococcus mutans metabolises dietary sucrose to form insoluble polymers of glucose. What does this allow them to do?

A
  • Stick to surfaces
28
Q

Streptococcus mutans are able to survive in low pH environments, Why is this advantageous for them?

A
  • Low pH promotes enamel dissolution (demineralisation)
29
Q

Bacteria have to have a range of virulence factors to be effective. Give examples of these? (5)

A
  • Adhesins
  • Binding proteins (things that take your sugar and turn them into glucans)
  • Sugar modifying enzymes
  • Polysaccharides (protection from external sources
  • Acid tolerance and adaptation (ATPase - membrane pumps which fire out H+ so as pH goes down it has the capacity to pump them out and maintain internal equilibrium at a more neutral pH)
30
Q

Briefly explain sucrose metabolism?

A

If give sugar glucose transferase and frucosyl transferase will produce fructans or glucans from sucrose and these 2 things are incredibly sticky

31
Q

What are the properties of water soluble glucans? (2)

A
  • Readily degraded for energy source

- Formation of lactic acid

32
Q

What are the propertied of water insoluble glucans? (2)

A
  • Sticky and hard - act as cement
  • Promote accumulation of plaque

(not what we want - like cement means they are difficult to remove so need something more industrial to remove it so more than brushing)

33
Q

What are bacterial polysaccharides good for?

A
  • These help to stick to each other and other bacterium’s
34
Q

What are 3 acids that can occur in the mouth that will promote demineralisation?

A
  • Lactic acid (strongest with pH 3.5)
  • Formic acid
  • Acetic acid
  • pH drops below 5.5 -> demineralisation
35
Q

What are the ways in which S. mutans can tolerate acid? (3)

A
  • Maintains pH balance
  • Alters cell membrane
  • Protection and repair mechanisms
36
Q

How can strep mutans maintain pH balance?

A
  • Extrusion of H+ ions through a proton translocating F1-F0 ATPase (maintains physiological pH levels)
37
Q

How can Strep mutans alter the cell membrane to provide acid tolerance?

A

Increase in the proportion of mono-unsaturated membrane fatty acids - decreased proton permeability

38
Q

How can Strep mutans use protection and repair mechanisms to provide acid tolerance?

A
  • Up-regulation of molecular chaperones, proteases and DNA repair mechanisms
39
Q

What is the anti-caries systemic effect of fluoride?

A
  • Incorporation of ingested fluoride into developing enamel as fluorapatite which reduces its solubility in acid and promotes remineralisation
40
Q

What is the anti-caries Topical effect of fluoride?

A

The surface layer of enamel is converted into fluorapatite which reduces its solubility in acid and promotes remineralisation

41
Q

What is the anti-caries Antimicrobial effect of fluoride?

A
  • Fluoride inhibits plaque metabolism and is concentrated within plaque. Activity increases at pH values <5, especially in the case of S. mutans
42
Q

What is the oral microbiome like in a person with a high protein diet? (3)

A
  • Few acidogenic organisms -> ammonia produced
  • More gram-negatives
  • Secondary metabolites - malodour
43
Q

What is the oral microbiome like in a person with a high carbohydrate diet? (3)

A
  • Metabolism reduces pH
  • Aciduric organisms thrive
  • Streptococci and lactobacilli
44
Q

What are ways of managing caries microbiology?

A
  • Diet
  • Fluoride (promotes remineralisation)
  • Polyol gums (increases saliva flow)
  • Probiotics
  • Vaccines
  • Antimicrobial peptides

BDS3 Caries Symposium (7 decks)

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