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Microbiology > Oral Bacteria A (EXAM III) > Flashcards

Oral Bacteria A (EXAM III) Flashcards

1
Q

The small ribosomal subunit for bacteria is composed of:

A

16S ribosomal RNA

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2
Q

Around how many nucleotides are present in the 16S rRNA and how many proteins comprises this?

A

~1540 nucleotides
21 proteins

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3
Q

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

A

Basing identification on the 16S ribosomal RNA (rRNA) gene sequencing

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4
Q

Why do we use the 16S ribosomal RNA to evaluate phylogenetic relationships among microorganisms?

A

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

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5
Q

The uniqueness of the ______ regions enables taxonomic positioning & identification of bacteria

A

Variable regions

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6
Q

One of the highest concentrations of bacteria in the body:

A

Biofilm on tooth surface

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7
Q

Colonizing bacteria interact with the ______ on the tooth surface

A

Acquired pellicle

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8
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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9
Q

Describe the acquired pellicle:

A

Film deposited on tooth surface composed of:

  1. Molecules in saliva (predominant)
  2. Material shed from bacterial cell surfacecs
  3. Polymers form gingival crevicular fluid
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10
Q

Once the acquired pellicle is on the surface of the tooth _________ of bacteria occurs to the pellicle surface

A

Passive transport

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11
Q

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

A
  1. Strep gordonii
  2. Strep oralis
  3. Strep mitis
  4. Strep sanguinis
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12
Q

The bacteria have _____ located on the bacterial surface, and bind to _____ in the pellicle

A

Adhesins; receptors

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13
Q

Polymers from saliva & bacteria:

A

Pellicle receptors

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14
Q

Once the strep species bind to the pellicle, adhesion is usually ____

A

Irreversible

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15
Q

Major adhesins of streptococci include:

A

Antigen I/II

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16
Q

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

A

Human salivary glycoproteins, other bacteria & calcium

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17
Q

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

A

Coaggregation

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18
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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19
Q

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

A

Microenvironemtn

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20
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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21
Q

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

A

Multiplying

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22
Q

An important component of the bacterial biofilm, especially in streptococci species:

A

Glucan production

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23
Q

Streptococci produce _____ which are extracellular enzymes

A

Glucosyltransferases

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24
Q

Streptococci produce glucosyltransferases which are extracellular enzymes that:

A

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

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25
Q

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

A

Glucosyltransferase

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26
Q

What the glucosyltransferases polyermize the glucose moiety of sucrose into?

A
  1. Glucan polymers
  2. Other polysaccharides
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27
Q

Branched-chain polysaccharides containing alpha(1-6) & alpha(1-3) linkages:

A

Glucans

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28
Q

Glucans are branched-chain polysaccharids containing what linkages?

A

Alpha(1-6) & Alpha(1-3)

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29
Q

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

A

Ferment it into acid

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30
Q

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

A

Cement; produce & bind to them

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31
Q

As bacteria continue to build up & create these cement-like layers, what occurs:

A

Oxygen levels drop

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32
Q

As bacteria continue to build up & create these cement-like layers, & oxygens level drop, this allows:

A

The later colonizers to enter the biofilm & begin proliferation

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33
Q

Late colonizers include:

(category)

A

Obligate anaerobes

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34
Q

What species of bacteria are the obligate anaerobes that are late colonizers?

A
  1. Prevotella melaninogenicus
  2. Prevotella oralis
  3. Veionella spp.
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35
Q

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

A

Between the teeth & dental gingival crevice

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36
Q

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

A

Detachment of bacteria & colonization of new sites

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37
Q

How do bacteria forming the dental biofilm detach & colonize at new sites?

A

Some bacteria will shed or degrade their adhesins to facilitate their release

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38
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 interaction
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39
Q

Altered properties of bacteria in a biofilm:

Upregulation of genes for:

A

Extracellular polysaccharide synthesis (glucan & fructan production)

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40
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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41
Q

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

A

Antibiotics rely on bacterial cell growth

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42
Q

Why would expression of novel surface-associated phenotypes lead to increased resistance to antimicrobial agents?

A

This prevents antimicrobial agents from penetrating the biofilm

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43
Q

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

A

Synergistic & antagonistic

44
Q

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

A

Degradation of complex nutrients

45
Q

An antagonistic interaction between bacteria closely spaced in the biofilm results in:

A

Bacteriocinis

46
Q

What are bacteriocins:

A

Antimicrobial compounds that sculpt the composition of the biofilm

47
Q

The dental plaque will eventually reach _____ which means:

A

Microbial homeostasis; stability in bacterial composition

48
Q

Breakdown of homeostasis alters bacterial composition of the biofilm by:

A
  1. reduction in saliva flow
  2. increased consumption of sucrose
49
Q

Reduction in saliva flow & increased consumption of sucrose can lead to:

A

Caries

50
Q

What is the main bacteria responsible for caries development?

A

Mutans streptococci

51
Q

Fermentation in the biofilm produces acids including:

A
  1. Lactic acid
  2. Acetic acid
  3. Formic acid
52
Q

Acid demineralizes teeth by (2):

A
  1. Solubilizes calcium & phosphate (produced from hydroxyapatite)
  2. Gets reprecipitation of calcium when pH increases (becomes less acidic)
53
Q

Regular snacking on high sucrose foods creates:

A

A prolonged acid environment

54
Q

In a prolonged acid environment ___>____:

A

Demineralization > remineralization

55
Q

_____ dissolves slowly but ______ is more easily attacked & colonized by bacteria:

A

Enamel; dentin

56
Q

Because its protein rich, many bacteria can grow here:

A

Dentin

57
Q

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

A

Root canal becomes invaded & abscesses form

58
Q

______ is required for the accumulation of mutans streptococci

A

Sucrose

59
Q

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

A

Glucosyltransferases (GTFs)

60
Q

Glucosyltransferases are constitutively synthesized by:

A

All mutans streptococci

61
Q

What is the mutans streptococci adhesin?

A

Antigen I/II

62
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

63
Q

The metabolism of various saccharides (including glucose & fructose) by the accumulating bacterial biofilm results in the production & secretion of considerable amounts of the metabolic end product:

A

Lactic acid

64
Q

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

A

Lactic acid formation & subsequent demineralization

65
Q

_____ occurs with age and this changes the ____

A

Gingival recession; microbial homeostasis

66
Q

When gingival recession occurs, _____ surface of the root is exposed & made vulnerable to bacterial colonization:

A

Cementum surface

67
Q

60% of individuals over 60 years old have:

A

Root caries

68
Q

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

A

Mutans streptococci & lactobacilli

(In addition actinomyces viscous & actinomycete naeslundii may also play a role)

69
Q

Cariogenic bacteria rapidly transport _____ to conver to ____

A

Fermentable sugars; acid

70
Q

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

A

Rapid

71
Q

Cariogenic bacteria have multiple ____ including ____

A

sugar transporters; PEP-PTS systems

72
Q

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

A

Group translocation

73
Q

When the molecule being transported into the cell is being chemically altered DURING transport:

A

Group translocation

74
Q

A pathogenic property of cariogenic bacteria is the production of:

A

Extracellular & intracellular polysaccharides

75
Q

The extracellular polysaccharides produced by cariogenic bacteria include:

A

Glucans & fructans

76
Q

The intracellular polysaccharides produced by cariogenic bacteria allow for:

A

Intracellular storage- allows acid production even when sucrose is not available

77
Q

Cariogenic bacteria have the ability to maintain ____ under extreme conditions

A

Sugar metabolism

78
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

79
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

80
Q

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

A

Acidic pH optima

81
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

82
Q

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

A

Alkali production

83
Q

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

A

Urea & arginine

84
Q

Urea produces ammonia via ______

Arginine produces ammonia via _____

A

Urease

Arginine deiminase

85
Q

Virulence factors of Strep. Mutans:

Contain ______ which are important to adhering these bacteria to the salivary pellicle

A

Surface antigens I/II

86
Q

Virulence factors of Strep. Mutans:

They have ______ & ______ that produce sugar polymers in the exterior of the cell

A

Glucosyltransferases & fructosyltransferases

87
Q

Virulence factors of Strep. Mutans:

______ & ______ that they produce allow the bacteria to hydrolyze the sugar polymers they created and then utilize these in fermentation to ultimately produce acids

A

Fructanase & Dextranase

88
Q

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

A
  1. Non-specific plaque hypothesis
  2. Specific plaque hypothesis
89
Q

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

A

Non-specific hypothesis

90
Q

Hypothesis for basis of periodontal disease that states that 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

91
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

92
Q

-Traditional view
-based on the complexity of the dental plaque
-mechanisms of generating an inflammatory response
-LPS

A

Non-specific plaque hypothesis

93
Q

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

A

Treatment dictates that flora be suppressed continuously or periodically

94
Q

-Based on key illustrative examples including localized juvenile periodontists and acute necrotizing ulcerative gingivitis:

A

Specific plaque hypothesis

95
Q

What doe the specific plaque hypothesis recommend for treatment?

A

Either

  1. Locally delivered antimicrobial agents & systemic tetracycline treatment
  2. antibiotic mouth rinses with oxidizing agent & systemic metronidazole treatment
96
Q

Contributor to the specific plaque hypothesis, caused by spirochetes & fusobacterium nucleate & commonly referred to as trench mouth:

A

Acute necrotizing ulcerative gingivitis (ANUG)

97
Q

LJP (specific plaque hypothesis contributor):

A

Localized juvenile periodontitis

98
Q

Specific plaque hypothesis considers both:

A

Early onset & adult forms of periodontitis

99
Q

No single bacterial species is uniquely involved more of a polymicrobial infection:

A

Specific plaque hypothesis

100
Q

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

A
  1. Porphyromonas gingivalis
  2. Tannerella forsythia
  3. Treponema denticola (& other spirochetes)
101
Q

Kind of a bridge between the specific plaque & non-specific plaque hypotheses:

A

Porphyromonas gingivalis as a “keystone pathogen”

102
Q

-Leukotoxins
-Invasins
-Bacterioin
-Phospholipase C

are all virulence factors of:

A

Aggregatibacter actinomycetecomintans

103
Q

What immuno-inhibitory virulence-associated factor is common in aggregatibacter actinomycetencomitans?

A

Capsular polysaccharide

104
Q

-Capsule
-Hemolysin
-Leukocidin/leukotoxin
-Superoxide dismutase

are all virulence factors of:

A

Fusobacterium nucleatum

105
Q

-Brown/black pigment
-Collagenase
-Hyaluronidase
-Protease
-Hemolysin

are all virulence factors of:

A

Prevotella intermedia

Microbiology (22 decks)

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