Bacteria-Oral Bacteria A-with highlights

Question 1

Identifying oral bacteria

Molecular techniques

Answer 1

often target 16S rRNA genes

Question 2

Gold standard of taxonomic classification

Answer 2

ribosomal RNA gene sequencing

Question 3

One of the highest concentrations of bacteria in the body

Answer 3

Dental plaque

•Biofilm on tooth surface

Question 4

Colonizing bacteria interact with acquired ………

Answer 4

Colonizing bacteria interact with acquired pellicle

Question 5

film composition (pellicle)=

Answer 5

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

Question 6

B. Passive transport of bacteria to pellicle surface

Initial colonization is by ………..

Answer 6

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

Question 7

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

Answer 7

Adhesins on bacterial surface bind to receptors in the pellicle.

Question 8

Pellicle receptors = polymers from saliva and bacteria

Adhesion is

Answer 8

Adhesion is usually irreversible

Question 9

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

Answer 9

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

Question 10

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

Answer 10

Subsequent attachment of these species and other

bacterial species occurs by coaggregation

Question 11

coaggregation

Answer 11

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

Question 12

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

Answer 12

Actinomyces naeslundii
Actinomyces viscosus
Streptococcus gordonii

Question 13

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

Answer 13

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

Question 14

Glucan production

Streptococci produce ……………

Answer 14

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

Question 15

glucosyltransferases

Answer 15

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

Question 16

Glucans =

Answer 16

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

Question 17

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

Answer 17

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

Question 18

Products of ferminatation include

Answer 18

Acetate lactate and formate

Question 19

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

There are especially found where?

Answer 19

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

Especially between teeth and dental gingival crevice
G. Get

Question 20

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

Answer 20

o2 levels drop

Question 21

G. how to bacteria colonize new sites?

Answer 21

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

Question 22

Altered properties of bacteria in a biofilm

Answer 22

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)

Question 23

Altered properties of bacteria in a biofilm

Increased resistance to antimicrobial agents occurs through what mechanisms.

Answer 23

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

Question 24

Metabolic interaction between closely spaced bacteria

Answer 24

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

Question 25

Plaque eventually reaches a

Answer 25

microbial homeostasis | = stability in bacterial composition

Question 26

Caries can result

Answer 26

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

Question 27

Streptococcus mutans | Streptococcus sobrinus

Answer 27

A-hole guys cause caries

Question 28

Fermentation in biofilm produces

Answer 28

``` Fermentation in biofilm produces acids lactic acid (as well as acetic acid and formic acid) ```

Question 29

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

Answer 29

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

Question 30

This attachment is thought to be the first event in the | formation of dental plaque.

Answer 30

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

Question 31

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 ....................

Answer 31

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

Question 32

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

Answer 32

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

Question 33

Gingival recession occurs with age | This fact changes the ................................

Answer 33

Gingival recession occurs with age | This fact changes the microbial homeostasis

Question 34

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

Answer 34

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)

Question 35

Cariogenic bacteria have multiple sugar transporters | Including

Answer 35

PEP-PTS systems (group translocation system)

Question 36

Glucans and Fructans (extracellular) | Intracellular storage - allows ......................

Answer 36

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

Question 37

MS and lactobacilli are

Answer 37

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)

Question 38

MS and lactobacilli

Answer 38

maintain a favorable intracellular environment | pump out protons even into acidic surroundings

Question 39

MS and lactobacilli bacterial enzymes have more ...................... pH optima produce acid-stress response proteins to .................

Answer 39

MS and lactobacilli bacterial enzymes have more ...................... pH optima produce acid-stress response proteins to protect cell contents

Question 40

MS and Lactobacilli ``` ATP usage is coupled to protons being pumped ........... (using ATP synthesized by ...............) ```

Answer 40

``` ATP usage is coupled to protons being pumped out (using ATP synthesized by glycolysis) ```

Question 41

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

Answer 41

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

Question 42

noncariogenic bacteria =

Answer 42

Alkali production

Question 43

Non-specific plaque hypothesis

Answer 43

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

Question 44

Specific plaque hypothesis

Answer 44

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

Question 45

Aggregatibacter actinomycetemcomitans

Answer 45

Localized juvenile periodontitis (LJP)(now classified as aggressive periodontitis) 1-5 out of 1000 teenagers produces a leukotoxin (LT) that inhibits neutrophils

Question 46

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

Answer 46

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

Question 47

Acute necrotizing ulcerative gingivitis (ANUG) | Specific plaque hypothesis

Answer 47

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

Question 48

Porphyromonas gingivalis Tannerella forsythia Treponema denticola (& other spirochetes)

Answer 48

Specific plaque hypothesis (continued) | Consider both early-onset and adult forms of disease

Question 49

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

Answer 49

Aggregatibacter actinomycetemcomitans Virulence Factors

Question 50

Aggregatibacter actinomycetemcomitans | Immunoinhibitory virulence-associated characteristics

Answer 50

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

Question 51

Phospholipase C | • Hydrolyzation of host cell membrane

Answer 51

Aggregatibacter actinomycetemcomitans Virulence Factors

Question 52

Fusobacterium nucleatum Virulence factors

Answer 52

Capsule Hemolysin • Leukocidin/leukotoxin Superoxide dismutase

Question 53

Prevotella intermedia Virulence factors

Answer 53

``` 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 ```