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microbiology > Oral Bacteria A- Exam III > Flashcards

Oral Bacteria A- Exam III Flashcards

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1
Q

The small ribosomal subunit for bacteria is composed to:

A

16s ribosomal RNA

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2
Q

Around how many nucleotides are present in the 16s rRNA?

A

1540

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3
Q

How many proteins comprise the 16s rRNA

A

21 proteins

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4
Q

This has become the gold standard in microbial and taxonomic classification of bacterial species in microbiology:

A

basing identification on the 16s ribosomal RNA gene sequencing

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5
Q

Why do we use the 16s rRNA for evaluating phylogenetic relationships among microorganisms??

A

the degree of conservation of genes differs considerably; conserved regions of the gene are identical for all bacteria while the variable regions contain specific sites unique to individual bacteria

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6
Q

The uniqueness of the ____ regions enables taxonomic positioning and identification of bacteria:

A

variable regions

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7
Q

one of the highest concentrations of bacteria in the body:

A

biofilm on tooth surface

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8
Q

Colonizing bacteria interact with the ___ on the tooth surface

A

acquired pellicle

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9
Q

In the formation of dental plaque, bacteria never come into contact with a ___. The tooth surface is coated with an ___.

A

clean tooth surface; acquired pellicle

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10
Q

Describe the acquired pellicle:

A

Film deposited on tooth surface composed of:
1. molecules in saliva (predominant)
2. material shed from bacterial cell surfaces
3. polymers from GCF

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11
Q

Once this acquired pellicle is on the surface of the tooth, ___ of bacteria occurs the pellicle surface

A

passive transport

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12
Q

The initial colonization of bacteria to the pellicle surface is by what bacterial species?

A
  1. strep gordonii
  2. strep oralis
  3. strep mitis
  4. strep sanguinis
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13
Q

The bacteria have ___ on the bacterial surface and bind to ___ in the pellicle

A

adhesins; receptors

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14
Q

Polymers from saliva and bacteria:

A

pellicle receptors

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15
Q

Once the strep species bind to the pellicle, adhesion is usually ___.

A

irreversible

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16
Q

Major adhesins of streptococci include:

A

Antigen I/II

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17
Q

Streptococcus have important adhesins including antigen I/II that also bind:

A

human salivary glycoproteins , other bacteria & calcium

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18
Q

Once the initial colonizing bacteria are attached to the tooth surface they can become binding sites for additional bacterial species, this is referred to as:

A

coaggregation

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19
Q

Following the initial streptococcus species that colonize, the additional bacterial species that coaggregate include:

A
  1. actinomyces naeslundii
  2. actinomyces viscosus
  3. streptococcus gordonii
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20
Q

Through bacterial metabolism through the multiple layers of species, this creates a:

A

microenvironment

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21
Q

The microenvironment created through bacterial metabolism of the initial colonizing and coaggregation layers of bacteria supports additional species of bacteria including:

A
  1. strep mutans
  2. strep sobrinus
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22
Q

The bacteria are not just binding to the developing biofilm, they are are also:

A

mutliplying

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23
Q

An important component of the biofilm (especially in the streptococcus species) is:

A

gluten production

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24
Q

Streptococci produce ____ which are extracellular enzymes:

A

glucosyltransferases

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25
Q

Streptococci produce glucosyltransferases that are extracellular enzymes that:

A

polymerize the glucose moiety of sucrose into glucan polymers and other polysaccharides

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26
Q

Extracellular enzymes that polymerize the glucose moiety of sucrose into glucan polymers and other polysaccharides

A

glucosyltransferases

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27
Q

What do the glucosyltransferases polymerize the glucose moiety of sucrose into:

A

glucan polymers and other polysaccharides

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28
Q

Branched-chain polysaccharides with alpha 1-6 and alpha 1-3 linkages:

A

glucans

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29
Q

Glucans are branched-chain polysaccharides containing what linkages:

A

alpha 1-6 and alpha 1-3

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30
Q

When bacteria cleave sucrose, they can take the resulting glucose and fructose and:

A

ferment it into acid

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31
Q

Glucans are like ____ (like long polymers) and bacteria both:

A

cement; produce and bind to them

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32
Q

As bacteria continue to build up and create these cement-like layers, what occurs?

A

oxygen levels drop

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33
Q

As bacteria continue to build up and create these cement-like layers, and oxygen levels drop, this allows:

A

the late colonizers to enter into the biofilm and begin to proliferate

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34
Q

Late colonizers include: (category)

A

obligate anaerobes

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35
Q

Later colonizers include obligate anaerobes such as:

A
  1. prevotella melaninogenicus
  2. prevotella oralis
  3. veillonella species
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36
Q

We see the drop of oxygen levels in the biofilm especially:

A

between the teeth and dental gingival crevice

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37
Q

In addition to all of the binding that is occurring to create the biofilm, you will also get some:

A

detachment of bacteria and colonization of new site

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38
Q

How do bacteria forming the dental biofilm death and colonize new sites?

A

Some bacteria will shed or degrade their adhesins to facilitate release

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39
Q

Altered properties of bacteria in a biofilm:

  1. ____ for extracellular polysaccharide synthesis
  2. Increased ___ to antimicrobial agents
  3. ____ between closely spaced bacteria
A
  1. up regulation of genes
  2. Increased resistance
  3. metabolic interacton
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40
Q

Altered properties of bacteria in a biofilm:

up regulation of genes for:

A

extracellular polysaccharide synthesis (glucan and fructan production)

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41
Q

Altered properties of bacteria in a biofilm:

Increased resistance to antimicrobial agents: (4)

A
  1. restricted penetration into biofilm
  2. inactivation by enzymes
  3. slow bacterial growth
  4. expression of novel surface-associated phenotypes
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42
Q

Why would slow growth rate of bacteria in biofilm lead to increased resistance to antimicrobial agents?

A

Antibiotics rely on bacterial growth

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43
Q

Why would expression of novel surface-associated phenotype led to increased resistance to anti-microbial agents?

A

This prevents antimicrobial agents from penetrating the biofilm

44
Q

Describe the metabolic interactions between closely spaced bacteria in the biofilm:

A

synergistic & antagonistic

45
Q

A synergistic interaction between closely spaced bacteria in the dental biofilm results in:

A

degradation of complex nutrients

46
Q

A antagonistic interaction between closely spaced bacteria in the dental biofilm results in:

A

bacteriocins (exclude susceptible strains)

47
Q

What are bacteriocins?

A

compounds that are antimicrobial and sculpt the composition of the biofilm

48
Q

The dental plaque eventually reaches ____ which means ____.

A

microbial homeostasis; stability in bacterial composition

49
Q

Breakdown of homeostasis alters bacterial composition of the biofilm by:

A
  1. reduction in saliva flow
  2. increased consumption of sucrose
50
Q

With reduction in saliva flow and increased consumption of sucrose for example, this might lead to:

A

caries

51
Q

What is the main bacteria responsible for caries development?

A

mutans streptococci

52
Q

Fermentation in the biofilm produces acids including:

A
  1. lactic acid
  2. acetic acid
    3 .formic acid
53
Q

Acid demineralizes the teeth by: (2)

A
  1. solubilizes calcium and phosphate (produced from hydroxyapatite)
  2. gets reprecipitation of calcium when pH increases (becomes less acidic)
54
Q

Regular snacking on high sucrose food creates:

A

prolonged acid ennvironment

55
Q

In a prolonged acid environment , _____ > ____

A

demineralization > remineralization

56
Q

____ dissolves slowly but ___ is more easily attacked and colonized by bacteria

A

enamel; dentin

57
Q

Because its protein rich, any different bacteria can grow here:

A

dentin

58
Q

Once bacteria are in the dentin, the disease rapidly progresses and :

A

root canal becomes invades and abscesses form

59
Q

____ is required for the accumulation of mutans streptococci:

A

sucrose

60
Q

In addition to sucrose, what else is retried for the accumulation of mutans streptococci?

A

Glucosyltransferases (GTFs)

61
Q

Glucosyltransferases are constituitively synthesized by:

A

mutans streptococci

62
Q

What is the mutans streptococcal adhesin?

A

antigen I/II

63
Q

Thought to be the second event in the formation of dental plaque:

A

In the presence of sucrose GTFs synthesize extracellular gluons from glucose

64
Q

The metabolism of various saccharides including glucose and fructose by the accumulated bacterial biofilm results in the production and secretion of considerable amounts of the metabolic end-product:

A

lactic acid

65
Q

Thought to be the third event in the formation of dental plaque and eventually results in carious lesions:

A

lactic acid formation

66
Q

____ occurs with age and this changes the ___.

A

gingival recession; microbial homeostasis

67
Q

When gingival recession occurs, ___ surface of the root is exposed and made vulnerable to bacterial colonization

A

cementum

68
Q

60% of individuals over 60 years old have:

A

root caries

69
Q

What are the likely pathogens responsible for root caries in elder individuals?

A

mutans streptococci and lactobacilli

In addition - actinomyceces viscosus & actinomycese naseslundii

70
Q

Cariogenic bacteria rapidly transport ____ to convert to ___

A

fermentable sugars; acid

71
Q

Compared to noncariogenic bacteria, the transport of fermentable sugars/conversion to acid by cariogenic can be described as:

A

rapid

72
Q

cariogenic bacteria have multiple ____ including ___.

A

sugar transporters; PEP-PTS systems

73
Q

PEP-PTS systems found in cariogenic bacteria are involved with the process of:

A

group translocation

74
Q

When the molecule being transported into the cells being chemically altered DURING TRANSPORT:

A

group translocation

75
Q

A pathogenic property of cariogenic bacteria is the production of:

A

extracellular and intracellular polysaccharides

76
Q

The extracellular polysaccharide produced by cariogenic bacteria include:

A

glucans & fructans

77
Q

The intracellular polysaccharides produced by cariogenic bacteria allow for:

A

intracellular storage- allows for acid production even when sucrose is not available

78
Q

cariogenic bacteria have the ability to maintain ___ under extreme conditions

A

sugar metabolism

79
Q

What type of conditions are more tolerated by mutans streptococcus and lactobacilli? What does this mean?

A

acidic conditions; they are both acid producing AND acid tolerant

80
Q

The main way that cariogenic bacteria are able to tolerate acidic conditions is by:

A

using ATPase to pump out protons even in acidic conditions (reverse) which allows for a more favorable intracellular environment

81
Q

Another way cariogenic bacteria are able to tolerate acidic condition is that their bacterial enzymes have a more:

A

acidic pH optima

82
Q

In addition to the intracellular environment and acidic pH optima of enzymes, cariogenic bacteria also produce ___ to protect cell contents

A

acid-stress response proteins

83
Q

A notable property of noncariogenic bacteria that allows them to survive in acidified environment (due to cariogenic bacteria) is:

A

alkali production

84
Q

____ & ____ are major substrates for alkali production via the generation of ammonia (NH3)

A

urea and arginine

85
Q

Urea produces ammonia via:

Arginine produces ammonia via:

A

urease; arginine deiminase

86
Q

Virulence factors of strep mutans:

Contain ____ which are important for adhering these bacteria to the salivary pellicle

A

surface antigens I/II

87
Q

Virulence factors of strep mutans:

They have ___ & ___ that produce sugars polymers in the exterior of the cell

A

glucosyltransferases & fructosyltransferases

88
Q

Virulence factors of strep mutans:

___ & ___ that they produce allow the bacteria to hydrolyze the sugar polymers that they create and utilize these in fermentation to end up producing acids

A

fructanase & dextranase

89
Q

What are the two hypothesis for the basis of periodontal disease?

A
  1. non-specific plaque hypothesis
  2. specific plaque hypothesis
90
Q

Hypothesis for basis of periodontal disease that states, the disease is due to the host response to non-specific growth of bacteria on tooth surfaces:

A

non-specific hypothesis

91
Q

Hypothesis for basis of periodontal disease that states, the disease is due to a limited number of species which produce biologically active molecules that are pro inflammatory or antigenic

A

specific plaque hypothesis

92
Q

The non-specific plaque hypothesis views the cause of periodontal disease as more of a ____, whereas the specific plaque hypothesis views the cause of periodontal disease as more of a ___ cause.

A

inflammatory disease; infection

93
Q
  • traditional view
  • based on the complexity of dental place
  • mechanisms of generating an inflammatory response
  • LPS
A

Non-specific plaque hypothesis

94
Q

What does the non-specific plaque hypothesis recommend for treatment?

A

treatment dictates that flora be suppressed continually or periodically

95
Q
  • based on key illustrative examples including localized juvenile periodontitis and acute necrotizing ulcerative gingivitis
A

Specific plaque hypothesis

96
Q

What does the specific plaque hypothesis recommend for treatment?

A

either
1. locally delivered antimicrobial agents & systemic tetracycline treatment

  1. antibiotic mouth rinses with oxidizing agents and systemic metronidazole treatment
97
Q

Contribute to the basic plaque hypothesis, caused by spirochetes and fusobacterium nucelatum, and commonly referred to as Trench mouth:

A

acute necrotizing ulcerative gingivitis (ANUG)

98
Q

LJP (specific plaque hypothesis contributer)

A

localized juvenile periodontitis

99
Q

Specific plaque hypothesis considers both:

A

early onset and adult forms of periodontitis

100
Q

No single bacterial species uniquely involved; more of a poly microbial infection:

A

specific plaque hypothesis

101
Q

According to the specific plaque hypothesis, what certain bacteria do we see continuously associated with lesions/periodontal pockets?

A
  1. porphyromonas gingivalis
  2. tannerella forsythia
  3. treponema denticola
102
Q

Kinda of a bridge between the specific plaque hypothesis and non-specific plaque hypotheses:

A

Porphyromonas gingival as “keystone pathogen”

103
Q
  • leukotoxin
  • invasins
  • bacteriocin
  • phospholipase c

These are all virulence factors of:

A

aggregatibacter actinomycetemcomitans

104
Q

What immunoinhibitory virulence associated factor is common in aggregatibacter actinomycetemcomitans?

A

capsular polysaccharide

105
Q
  • Capsule
  • Hemolysin
  • Leukocidin/Leukotoxin
  • Superoxide Dismutase

These are all virulence factors of:

A

fusobacterium nucleatum

106
Q
  • brown/black pigment
  • collagenase
  • hyaluronidase
  • protease
  • hemolysin

These are all virulence factors of:

A

prevotella intermedia

microbiology (24 decks)

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