Oral Bacteria A (EXAM III) Flashcards
1
Q
The small ribosomal subunit for bacteria is composed of:
A
16S ribosomal RNA
2
Q
Around how many nucleotides are present in the 16S rRNA and how many proteins comprises this?
A
~1540 nucleotides
21 proteins
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
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
5
Q
The uniqueness of the ______ regions enables taxonomic positioning & identification of bacteria
A
Variable regions
6
Q
One of the highest concentrations of bacteria in the body:
A
Biofilm on tooth surface
7
Q
Colonizing bacteria interact with the ______ on the tooth surface
A
Acquired pellicle
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
9
Q
Describe the acquired pellicle:
A
Film deposited on tooth surface composed of:
- Molecules in saliva (predominant)
- Material shed from bacterial cell surfacecs
- Polymers form gingival crevicular fluid
10
Q
Once the acquired pellicle is on the surface of the tooth _________ of bacteria occurs to the pellicle surface
A
Passive transport
11
Q
The initial colonization of the bacteria to the pellicle surface is by what species?
A
- Strep gordonii
- Strep oralis
- Strep mitis
- Strep sanguinis
12
Q
The bacteria have _____ located on the bacterial surface, and bind to _____ in the pellicle
A
Adhesins; receptors
13
Q
Polymers from saliva & bacteria:
A
Pellicle receptors
14
Q
Once the strep species bind to the pellicle, adhesion is usually ____
A
Irreversible
15
Q
Major adhesins of streptococci include:
A
Antigen I/II
16
Q
Streptococcus have important adhesins including antigen I/II that also bind:
A
Human salivary glycoproteins, other bacteria & calcium
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
18
Q
Following the initial streptococcus species that colonize, the additional bacterial species that coaggregate include:
A
- Actinomyces Naeslundii
- Actinomyces Viscosus
- Streptococcus Gordonii
19
Q
Through bacterial metabolism by the multiple layers of species, this creates a:
A
Microenvironemtn
20
Q
The microenvironment created through bacterial metabolism of the initial colonizing and coaggregation layers of bacteria supports additional species of bacteria including:
A
- Strep mutans
- Strep sobrinus
21
Q
The bacteria are not just binding to the bacterial biofilm, they are also:
A
Multiplying
22
Q
An important component of the bacterial biofilm, especially in streptococci species:
A
Glucan production
23
Q
Streptococci produce _____ which are extracellular enzymes
A
Glucosyltransferases
24
Q
Streptococci produce glucosyltransferases which are extracellular enzymes that:
A
Polymerize the glucose moiety of sucrose into glucan polymers and other polysaccharides
25
Extracellular enzymes that polymerize the glucose moiety of sucrose into glucan polymers & other polysaccharides:
Glucosyltransferase
26
What the glucosyltransferases polyermize the glucose moiety of sucrose into?
1. Glucan polymers
2. Other polysaccharides
27
Branched-chain polysaccharides containing alpha(1-6) & alpha(1-3) linkages:
Glucans
28
Glucans are branched-chain polysaccharids containing what linkages?
Alpha(1-6) & Alpha(1-3)
29
When bacteria cleave sucrose, they can take the resulting glucose & fructose and:
Ferment it into acid
30
Glucans are like _____ (like long polymers) and bacteria both:
Cement; produce & bind to them
31
As bacteria continue to build up & create these cement-like layers, what occurs:
Oxygen levels drop
32
As bacteria continue to build up & create these cement-like layers, & oxygens level drop, this allows:
The later colonizers to enter the biofilm & begin proliferation
33
Late colonizers include:
(category)
Obligate anaerobes
34
What species of bacteria are the obligate anaerobes that are late colonizers?
1. Prevotella melaninogenicus
2. Prevotella oralis
3. Veionella spp.
35
We see the drop of oxygen levels in the biofilm especially:
Between the teeth & dental gingival crevice
36
In addition to all the binding that is occurring to create the biofilm you will also get some:
Detachment of bacteria & colonization of new sites
37
How do bacteria forming the dental biofilm detach & colonize at new sites?
Some bacteria will shed or degrade their adhesins to facilitate their release
38
Altered properties of bacteria in a biofilm:
1. ______ for extracellular polysaccharide synthesis
2. Increased ______ to antimicrobial agents
3. ______ between closely spaced bacteria
1. Up-regulation of genes
2. Increased resistance
3. Metabolic interaction
39
Altered properties of bacteria in a biofilm:
Upregulation of genes for:
Extracellular polysaccharide synthesis (glucan & fructan production)
40
Altered properties of bacteria in a biofilm:
Increased resistance to antimicrobial agents (4):
1. Restricted penetration into biofilm
2. Inactivation by enzymes
3. Slow bacterial growth
4. Expression of novel surface-associated phenotypes
41
Why would slow growth rate of bacteria in the biofilm lead to increased resistance to antimicrobial agents?
Antibiotics rely on bacterial cell growth
42
Why would expression of novel surface-associated phenotypes lead to increased resistance to antimicrobial agents?
This prevents antimicrobial agents from penetrating the biofilm
43
Describe the metabolic interactions between closest spaced bacteria in the biofilm:
Synergistic & antagonistic
44
A synergistic interaction between bacteria closely spaced in the biofilm results in:
Degradation of complex nutrients
45
An antagonistic interaction between bacteria closely spaced in the biofilm results in:
Bacteriocinis
46
What are bacteriocins:
Antimicrobial compounds that sculpt the composition of the biofilm
47
The dental plaque will eventually reach _____ which means:
Microbial homeostasis; stability in bacterial composition
48
Breakdown of homeostasis alters bacterial composition of the biofilm by:
1. reduction in saliva flow
2. increased consumption of sucrose
49
Reduction in saliva flow & increased consumption of sucrose can lead to:
Caries
50
What is the main bacteria responsible for caries development?
Mutans streptococci
51
Fermentation in the biofilm produces acids including:
1. Lactic acid
2. Acetic acid
3. Formic acid
52
Acid demineralizes teeth by (2):
1. Solubilizes calcium & phosphate (produced from hydroxyapatite)
2. Gets reprecipitation of calcium when pH increases (becomes less acidic)
53
Regular snacking on high sucrose foods creates:
A prolonged acid environment
54
In a prolonged acid environment ___>____:
Demineralization > remineralization
55
_____ dissolves slowly but ______ is more easily attacked & colonized by bacteria:
Enamel; dentin
56
Because its protein rich, many bacteria can grow here:
Dentin
57
Once bacteria are in the dentin the disease rapidly progresses and:
Root canal becomes invaded & abscesses form
58
______ is required for the accumulation of mutans streptococci
Sucrose
59
In addition to sucrose, what else is required for the accumulation of mutans streptococci?
Glucosyltransferases (GTFs)
60
Glucosyltransferases are constitutively synthesized by:
All mutans streptococci
61
What is the mutans streptococci adhesin?
Antigen I/II
62
Thought to be the second event in the formation of dental plaque:
In the presence of sucrose, GTFs synthesize extracellular gluons from glucose
63
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:
Lactic acid
64
Thought to be the third event in the formation of dental plaque & eventually results in carious lesions:
Lactic acid formation & subsequent demineralization
65
_____ occurs with age and this changes the ____
Gingival recession; microbial homeostasis
66
When gingival recession occurs, _____ surface of the root is exposed & made vulnerable to bacterial colonization:
Cementum surface
67
60% of individuals over 60 years old have:
Root caries
68
What are the pathogens responsible for root caries in elder individuals?
Mutans streptococci & lactobacilli
(In addition actinomyces viscous & actinomycete naeslundii may also play a role)
69
Cariogenic bacteria rapidly transport _____ to conver to ____
Fermentable sugars; acid
70
Compared to noncariogenic bacteria, the transport of fermentable sugars/conversion to acid by cariogenic bacteria can be described as:
Rapid
71
Cariogenic bacteria have multiple ____ including ____
sugar transporters; PEP-PTS systems
72
PEP-PTS symptoms found in cariogenic bacteria are involved with the process of:
Group translocation
73
When the molecule being transported into the cell is being chemically altered DURING transport:
Group translocation
74
A pathogenic property of cariogenic bacteria is the production of:
Extracellular & intracellular polysaccharides
75
The extracellular polysaccharides produced by cariogenic bacteria include:
Glucans & fructans
76
The intracellular polysaccharides produced by cariogenic bacteria allow for:
Intracellular storage- allows acid production even when sucrose is not available
77
Cariogenic bacteria have the ability to maintain ____ under extreme conditions
Sugar metabolism
78
What type of conditions are more tolerated by Mutans streptococcus and lactobacilli?
What does this mean?
Acidic conditions; they are both acid-producing AND acid-tolerant
79
The main way that cariogenic bacteria are able to tolerate acidic conditions is by:
Using ATPase to pump out protons even in acidic conditions (reverse) which allows for a more favorable intracellular environment
80
Another way cariogenic bacteria are able to tolerate acidic conditions is that their bacterial enzymes have a more:
Acidic pH optima
81
In addition to the intracellular environment and acidic pH optima of enzymes, cariogenic bacteria also produce _____ to protect cell contents
Acid-stress response proteins
82
A notable property of noncariogenic Bactria that allows them to survive in the acidified environment (due to cariogenic bacteria) is:
Alkali production
83
____ & ____ are major substrates for alkali production via the generation of ammonia (NH3)
Urea & arginine
84
Urea produces ammonia via ______
Arginine produces ammonia via _____
Urease
Arginine deiminase
85
Virulence factors of Strep. Mutans:
Contain ______ which are important to adhering these bacteria to the salivary pellicle
Surface antigens I/II
86
Virulence factors of Strep. Mutans:
They have ______ & ______ that produce sugar polymers in the exterior of the cell
Glucosyltransferases & fructosyltransferases
87
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
Fructanase & Dextranase
88
What are the two hypothesis for the basis of periodontal disease:
1. Non-specific plaque hypothesis
2. Specific plaque hypothesis
89
Hypothesis for basis of periodontal disease that states the disease is to the host response to non-specific growth of bacteria on tooth surfaces:
Non-specific hypothesis
90
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:
Specific plaque hypothesis
91
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
Inflammatory disease; infection
92
-Traditional view
-based on the complexity of the dental plaque
-mechanisms of generating an inflammatory response
-LPS
Non-specific plaque hypothesis
93
What does the non-specific plaque hypothesis recommend for treatment?
Treatment dictates that flora be suppressed continuously or periodically
94
-Based on key illustrative examples including localized juvenile periodontists and acute necrotizing ulcerative gingivitis:
Specific plaque hypothesis
95
What doe the specific plaque hypothesis recommend for treatment?
Either
1. Locally delivered antimicrobial agents & systemic tetracycline treatment
2. antibiotic mouth rinses with oxidizing agent & systemic metronidazole treatment
96
Contributor to the specific plaque hypothesis, caused by spirochetes & fusobacterium nucleate & commonly referred to as trench mouth:
Acute necrotizing ulcerative gingivitis (ANUG)
97
LJP (specific plaque hypothesis contributor):
Localized juvenile periodontitis
98
Specific plaque hypothesis considers both:
Early onset & adult forms of periodontitis
99
No single bacterial species is uniquely involved more of a polymicrobial infection:
Specific plaque hypothesis
100
According to the specific plaque hypothesis what bacteria do we see continuously associated with lesions/periodontal pockets:
1. Porphyromonas gingivalis
2. Tannerella forsythia
3. Treponema denticola (& other spirochetes)
101
Kind of a bridge between the specific plaque & non-specific plaque hypotheses:
Porphyromonas gingivalis as a "keystone pathogen"
102
-Leukotoxins
-Invasins
-Bacterioin
-Phospholipase C
are all virulence factors of:
Aggregatibacter actinomycetecomintans
103
What immuno-inhibitory virulence-associated factor is common in aggregatibacter actinomycetencomitans?
Capsular polysaccharide
104
-Capsule
-Hemolysin
-Leukocidin/leukotoxin
-Superoxide dismutase
are all virulence factors of:
Fusobacterium nucleatum
105
-Brown/black pigment
-Collagenase
-Hyaluronidase
-Protease
-Hemolysin
are all virulence factors of:
Prevotella intermedia
