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MBE3 > Bacteria-Oral Bacteria A-with highlights > Flashcards

Bacteria-Oral Bacteria A-with highlights Flashcards

1
Q

Identifying oral bacteria

Molecular techniques

A

often target 16S rRNA genes

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2
Q

Gold standard of taxonomic classification

A

ribosomal RNA gene sequencing

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3
Q

One of the highest concentrations of bacteria in the body

A

Dental plaque

•Biofilm on tooth surface

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4
Q

Colonizing bacteria interact with acquired ………

A

Colonizing bacteria interact with acquired pellicle

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5
Q

film composition (pellicle)=

A

molecules in saliva (predominant)
material shed from bacterial cell surfaces
polymers from gingival crevicular fluid

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6
Q

B. Passive transport of bacteria to pellicle surface

Initial colonization is by ………..

A

B. Passive transport of bacteria to pellicle surface
Initial colonization is by Streptococcus species
Streptococcus gordonii
Streptococcus oralis
Streptococcus mitis
Streptococcus sanguis (now sanguinis)

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7
Q

………… on bacterial surface bind to receptors in the ………..

A

Adhesins on bacterial surface bind to receptors in the pellicle.

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8
Q

Pellicle receptors = polymers from saliva and bacteria

Adhesion is

A

Adhesion is usually irreversible

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9
Q

Streptococcus
Antigen ……… are important adhesins
Bind human salivary ……., other bacteria and calcium

A

Streptococcus
Antigen I/II are important adhesins
Bind human salivary glycoproteins, other bacteria and calcium

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10
Q 
Subsequent attachment (after strep) of these species and other
bacterial species occurs by ............
A

Subsequent attachment of these species and other

bacterial species occurs by coaggregation

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11
Q

coaggregation

A

bacteria binding to other bacteria
•additional bacteria bind to early-binding bacteria
and to each other
•multiple species coaggregate

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12
Q

C.Subsequent attachment of these species and other
bacterial species occurs by coaggregation
Important species at this stage:

A

Actinomyces naeslundii
Actinomyces viscosus
Streptococcus gordonii

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13
Q

D. Microenvironment created that supports additional species ……………………………

A

D. Microenvironment created that supports additional species
Streptococcus mutans
Streptococcus sobrinus

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14
Q

Glucan production

Streptococci produce ……………

A

Glucan production
Streptococci produce glucosyltransferases
extracellular enzymes
polymerize the glucose moiety of sucrose into
glucan polymers and other polysaccharides

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15
Q

glucosyltransferases

A

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

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16
Q

Glucans =

A

branched-chain polysaccharides
Alpha(1à6) linkage
Alpha(1à3) linkage

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17
Q

Glucans are like ………
Bacteria bind to ……………..
Bacteria are bound to ……. and to matrix of …….

A

Glucans are like cement
Bacteria bind to glucans
Bacteria are bound to each other and to matrix of glucans

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18
Q

Products of ferminatation include

A

Acetate lactate and formate

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19
Q

F. Late colonizers of the oral cavity include…..

There are especially found where?

A

Late colonizers include obligate anaerobes.
Prevotella melaninogenicus
Prevotella oralis
Veillonella spp

Especially between teeth and dental gingival crevice
G. Get

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20
Q

F. WTF happens to the environment of the oral cavity before late colonizers show up.

A

o2 levels drop

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21
Q

G. how to bacteria colonize new sites?

A

some bacteria shed adesins which facilitates and promotes colonization of new sites.

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22
Q

Altered properties of bacteria in a biofilm

A
  1. Up-regulation of genes for extracellular
    polysaccharide synthesis
  2. Increased resistance to antimicrobial agents
    a. restricted penetration of agent into biofilm
    b. inactivation of agents by enzymes concentrated in
    biofilm
    c. slow growth rate of bacteria in biofilm
    d. expression of novel surface-associated phenotypes
  3. Metabolic interaction between closely spaced bacteria
    Synergistic - degradation of complex nutrients
    Antagonistic - bacteriocins (exclude susceptible
    strains)
23
Q

Altered properties of bacteria in a biofilm

Increased resistance to antimicrobial agents occurs through what mechanisms.

A

a. restricted penetration of agent into biofilm
b. inactivation of agents by enzymes concentrated in
biofilm
c. slow growth rate of bacteria in biofilm
d. expression of novel surface-associated phenotypes

24
Q

Metabolic interaction between closely spaced bacteria

A

Synergistic - degradation of complex nutrients
Antagonistic - bacteriocins (exclude susceptible
strains)

25
Q

Plaque eventually reaches a

A

microbial homeostasis

= stability in bacterial composition

26
Q

Caries can result

A

Breakdown of homeostasis alters bacterial composition
•reduction in saliva flow
•increased consumption of sucrose

27
Q

Streptococcus mutans

Streptococcus sobrinus

A

A-hole guys cause caries

28
Q

Fermentation in biofilm produces

A 
Fermentation in biofilm produces acids
lactic acid (as well as acetic acid and formic acid)
29
Q

Acid demineralizes teeth
Solubilizes ………….. and ……………… (produced from hydroxyapatite)
Get reprecipitation when pH increases (becomes less acidic)

A

Acid demineralizes teeth
Solubilizes calcium and phosphate (produced from hydroxyapatite)
Get reprecipitation when pH increases (becomes less acidic)

30
Q

This attachment is thought to be the first event in the

formation of dental plaque.

A

The mutans streptococcal
adhesin (known as antigen I/II) interacts with -galactosides
in the saliva-derived glycoprotein constituents of the tooth
pellicle.

31
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

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 lactic acid

32
Q

In the presence of
sucrose, ………………. synthesize extracellular glucans from ………………
(after the breakdown of ………….. into………………. and ………….),
and this is thought to be the second event in the formation of
dental plaque

A

In the presence of
sucrose, GTFs synthesize extracellular glucans from glucose
(after the breakdown of sucrose into glucose and fructose),
and this is thought to be the second event in the formation of
dental plaque

33
Q

Gingival recession occurs with age

This fact changes the …………………………..

A

Gingival recession occurs with age

This fact changes the microbial homeostasis

34
Q

Actinomyces viscosus and Actinomyces naeslundii are the main MF’s associated with?

A

Cementum surface of the root is exposed and made
vulnerable to bacterial colonization
(Both of these Actinomyces species had been shown to
produce root surface caries in experimental animals)

35
Q

Cariogenic bacteria have multiple sugar transporters

Including

A

PEP-PTS systems (group translocation system)

36
Q

Glucans and Fructans (extracellular)

Intracellular storage - allows ………………….

A

Glucans and Fructans (extracellular)
Intracellular storage - allows acid production even
when sucrose in not available form external source.

Remenber glucans and fructans are made of sucruse

37
Q

MS and lactobacilli are

A

Ability to maintain sugar metabolism under extreme conditions.Acidic conditions more tolerated by MS and lactobacilli
(so they are both acid-producing and acid-tolerant)

38
Q

MS and lactobacilli

A

maintain a favorable intracellular environment

pump out protons even into acidic surroundings

39
Q

MS and lactobacilli bacterial enzymes have more …………………. pH optima

produce acid-stress response proteins to ……………..

A

MS and lactobacilli bacterial enzymes have more …………………. pH optima

produce acid-stress response proteins to protect cell contents

40
Q

MS and Lactobacilli

ATP usage is coupled
to protons being
pumped ...........
(using ATP
synthesized by
...............)
A 
ATP usage is coupled
to protons being
pumped out
(using ATP
synthesized by
glycolysis)
41
Q

………… and ………….. are the major substrates
for alkali production via the generation of
………………….

A

Urea and arginine are the major substrates
for alkali production via the generation of
ammonia (NH3)

42
Q

noncariogenic bacteria =

A

Alkali production

43
Q

Non-specific plaque hypothesis

A

Disease is due to the host
response to non-specific growth of bacteria on tooth surfaces
(inflammatory disease)

44
Q

Specific plaque hypothesis

A

disease is due to a limited number of
species which produce biologically active molecules that are
proinflammatory or antigenic (infection)

45
Q

Aggregatibacter actinomycetemcomitans

A

Localized juvenile periodontitis (LJP)(now classified as
aggressive periodontitis)
1-5 out of 1000 teenagers

produces a leukotoxin (LT) that inhibits neutrophils

46
Q

LJP is a ………………. bacterial infection
locally delivered antimicrobial agents
systemic……………………………. treatment

A

LJP is a treatable bacterial infection
locally delivered antimicrobial agents
systemic tetracycline treatment

47
Q

Acute necrotizing ulcerative gingivitis (ANUG)

Specific plaque hypothesis

A

Trench mouth of World War I
Spirochetes and Fusobacterium nucleatum
controlled by antibiotic mouth rinses with oxidizing agents
also systemic metronidazole (antibiotic) treatment

48
Q

Porphyromonas gingivalis
Tannerella forsythia
Treponema denticola (& other spirochetes)

A

Specific plaque hypothesis (continued)

Consider both early-onset and adult forms of disease

49
Q

Leukotoxin
• Cytotoxic to human PMNs, monocytes, and T-lymphoctyes
• Collagenase
• Endotoxin (LPS)
• Fibroblast inhibiting factor
• Invasins
– Aids in bacteria penetrating eukaryotic cells
• Iron repressible protein, iron regulated protein
• Enhancement of iron utilization from the environment or the host
• Bacteriocin
• Inhibition of growth or killing of other bacterial species, streptococcus
sanguis and actinomyces viscosus
• Adhesins (Fimbriae, extracellular vesicles, and amorphous
material
• Bacterial cell adherence and attachment to epithelial cells

A

Aggregatibacter actinomycetemcomitans Virulence Factors

50
Q

Aggregatibacter actinomycetemcomitans

Immunoinhibitory virulence-associated characteristics

A

Capsular polysaccharide
• Resistance to phagocytosis by PMNs, reduction in complement dependent
response by PMNs, increase In bone resorption

51
Q

Phospholipase C

• Hydrolyzation of host cell membrane

A

Aggregatibacter actinomycetemcomitans Virulence Factors

52
Q

Fusobacterium nucleatum Virulence factors

A

Capsule
Hemolysin
• Leukocidin/leukotoxin
Superoxide dismutase

53
Q

Prevotella intermedia Virulence factors

A 
The brown or black pigment
§ metabolic end-product of hemin, acts
as a defensive barrier that protects the
bacteria from the toxic effects of
oxygen
• Collagenase, hyaluronidase, and
protease
§ Degrade host tissues and cleave other
host derived molecules
• Hemolysin
§ Enhanced by the action of proteases
§ Favors the acquisition of iron, which
is an essential nutrient to their
metabolism and their survival

MBE3 (13 decks)

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