Oral Bacteria A Flashcards by Michael McMahan

> _____ different species present in oral cavity

700

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less than ____ of the oral bacteria have been cultured

half

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_____methods of oral bacteria: collect saliva, tongue blade, scrape from tooth surface, wick fluid from deep pockets (endodontic paper)

sampling

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Molecular techniques to ID oral bacteria -often target ______ genes

16S rRNA genes

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To ID bacteria, molecular techinques target the 16S rRNA gene which has a conserved and a variable portion. Which portion of this gene contains specific sites unique to individual bacteria to ID them?

Variable regions

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_____
•Biofilmon tooth surface
•One of the highest concentrations of bacteria in the body

Dental plaque

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Colonizing bacteria interact with acquired _____

pellicle

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T/F: Bacteria never come in contact with a clean tooth surface.

True

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Tooth surface is coated with an _______
•film deposited on tooth surface
•film composition =
-molecules in saliva (predominant)
-material shed from bacterial cell surfaces
-polymers from gingival crevicular fluid

acquired pellicle

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Initial colonization to pellicle surface is by ____ species

Streptococcus species

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What 4 strep sp make up the initial colonizing bacteria to pellicle?

Streptococcus gordonii
Streptococcus oralis
Streptococcus mitis
Streptococcus sanguis(now sanguinis)

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______ on bacterial surface bind to receptors in the pellicle.

Adhesins

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Adhesins on bacterial surface bind to ______ in the pellicle.

receptors

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Pellicle receptors= polymers from what 2 things?

saliva and bacteria

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Is adhesion to the pellicle reversible or irreversible?

Irreversible

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__________ are important adhesins (Strep)

Bind human salivary glycoproteins, other bacteria and calcium

Antigen I/II

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Subsequent attachment of these species and other bacterial species occurs by _______ after initial colonization

coaggregation

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

coaggregation

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The Important species at the coaggregation stage are what 3 bacteria?

Actinomyces naeslundii
Actinomyces viscosus
Streptococcus gordonii

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Once coaggregation occurs, a Microenvironment created that supports additional species
-Bacteria multiply in the developing biofilm

Streptococcus mutans

Streptococcus sobrinus

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Streptococci produce _________

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

glucosyltransferases

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

Glucans

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______ are like cement
Bacteria bind to these
Bacteria are bound to each other and to matrix of these

Glucans

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Once glucans are produced, oxygen levels drop and late colonizers include obligate anaerobes which include what 3 bacteria species? Especially between teeth and dental gingival crevice

Prevotella melaninogenicus
Prevotella oralis
Veillonella spp.

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After oxygen levels drop, Get some _______ of bacteria and _______ of new sites

detachment; colonization

Altered properties of bacteria in a biofilm include what 3 things?

1. Up-regulation of genes for extracellular polysaccharide synthesis 2. Increased resistance to antimicrobial agents 3. Metabolic interaction between closely spaced bacteria

Plaque eventually reaches a __________ = stability in bacterial composition

microbial homeostasis

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

bacterial composition

Bacterial role in caries development is mainly due to what bacteria?

Mutans streptococci

Fermentation in biofilm produces _______

lactic acid

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

Acid

Prolonged acidic environment created by regular snacking on high sucrose foods cause greater demineralization or remineralization?

Demineralization

Enamel or dentin dissolves slowly

Enamel

_______ more easily attacked and colonized by bacteria; it is protein rich/many different bacteria can grow

Dentin

60% of individual >60 years old have _______

Root caries

What are the likely pathogens of root surface caries?

Strep mutans and lactobacilli

Pathogenic bacteria Rapidly transport fermentable sugars/convert to _____

acid

Cariogenic bacteria have multiple sugar transportersIncluding ______ systems

PEP-PTS

_______ -molecule transported into the cell while being chemically altered

Group translocation

Pathogenic bacteria produce _____ and ______ polysaccs

Extra and intracellular

Glucans and Fructans are ______ polysaccs

(extracellular)

______polysaccs: storage -allows acid production even when sucrose in not available

Intracellular

What are the 3 ways cariogenic bacteria have the Ability to maintain sugar metabolism under extreme conditions?

a. maintain a favorable intracellular environment b. bacterial enzymes have more acidic pH optima c. produce acid-stress response proteins to protect cell contents

______ usage is coupled to protons being pumped out

ATP

Notable property of noncariogenic bacteria= _______ production

Alkali

_____ and _______ are the major substrates for alkali production via the generation of ammonia (NH3)

Urea and arginine

``` The following virulence factors are associated with _______: SpaP Glucosyltransferases Glucan-binding proteins Fructosyltransferase Fructanase Dextranase Intracellular polysacs PEP-PTS system ATPase Acid tolerance and adaptation ```

Strep mutans

_____ is a virulence factor of Strep mutans: adherence, binding to saliva coated tooth surfaces and salivary afflutinin

SpaP

_____ is a virulence factor of Strep mutans: procudtion of alpha1/3 and 1/6 linked polymers of glucose from sucrose; important for adherence and biofilm accumulation

Glucosyltransferases

_____ is a virulence factor of Strep mutans: binding of glucans produced by Glucosyltransferases; adherence to teeth; biofilm accumulation

Glucan-binding proteins

_____ is a virulence factor of Strep mutans: production of beta 1/2,6 linked polymers of fructose from sucrose that can primarily serve as an extracellular reserve of carbs; possibly implicated in adherence

Fructosyltransferase

_____ is a virulence factor of Strep mutans: hydrolysis of fructan polymers produced by Ftf; extends depth and duration of acidification

Fructanase

_____ is a virulence factor of Strep mutans: endo-hydrolytic cleavage of alpha 1,6 linked glucans; remodeling of glucan polymers to make them more water insoluble and releases glucose from polymers that can be used to produce acids

Dextranase

_____ is a virulence factor of Strep mutans: Large enzyme complex that uses ATP to pump protons from the cytoplasm; critical in acid tolerance

ATPase

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

Non-specific plaque hypothesis

Is Non-specific plaque hypothesis associated with infection or inflammatory disease?

inflammatory disease

Is specific plaque hypothesis associated with infection or inflammatory disease?

Infection

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

Specific plaque hypothesis

______ hypothesis: Traditional view Bacterial complexity of dental plaque Non-specific mechanisms of generating inflammatory response LPS Also:volatile fatty acids (butyrate, propionate, isobutyrate)sulfides (hydrogen sulfide, methyl mercaptan) Treatment dictates that flora be suppressed continuously or periodically

Non-specific plaque hypothesis

``` 1-5 out of 1000 teenagers Aggregatibacter actinomycetemcomitans can invade gingival tissues produces a leukotoxin (LT) that inhibits neutrophils is a treatable bacterial infection locally delivered antimicrobial agents systemic tetracycline treatment ```

Localized juvenile periodontitis (LJP)(now classified as aggressive periodontitis)

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

Acute necrotizing ulcerative gingivitis (ANUG)

_____ hypothesis: Localized juvenile periodontitis (LJP)(now classified as aggressive periodontitis) Acute necrotizing ulcerative gingivitis (ANUG) Consider both early-onset and adult forms of disease

Specific plaque hypothesis

_______ can invade gingival tissues | produces a leukotoxin (LT) that inhibits neutrophils; Main bacteria of LJP

Aggregatibacter actinomycetemcomitans

``` The following virulence factors are associated with _______: •Leukotoxin •Invasins •Bacteriocin Capsular polysaccharide •Phospholipase C ```

Aggregatibacter actinomycetemcomitans

______ is a virulence factor of Aggregatibacter actinomycetemcomitans: Cytotoxic to human PMNs, monocytes, and T-lymphoctyes

Leukotoxin

______ is a virulence factor of Aggregatibacter actinomycetemcomitans: –Aids in bacteria penetrating eukaryotic cells

•Invasins

______ is a virulence factor of Aggregatibacter actinomycetemcomitans: Inhibition of growth or killing of other bacterial species, streptococcus sanguis and actinomyces viscosus

Bacteriocin

______ is a virulence factor of Aggregatibacter actinomycetemcomitans:•Resistance to phagocytosis by PMNs, reduction in complement dependent response by PMNs, increase In bone resorption

Capsular polysaccharide

______ is a virulence factor of Aggregatibacter actinomycetemcomitans: •Hydrolyzation of host cell membrane

•Phospholipase C

``` The following virulence factors are associated with _______: •Capsule •Hemolysin •Leukocidin/leukotoxin •Superoxide dismutase ```

Fusobacterium nucleatum

______ is a virulence factor of Prevotella intermedia: §metabolic end-product of hemin, acts as a defensive barrier that protects the bacteria from the toxic effects of oxygen

•The brown or black pigment

______ is a virulence factor of Prevotella intermedia: §Degrade host tissues and cleave other host derived molecules; what 3 things?

•Collagenase, hyaluronidase, and protease

______ is a virulence factor of Prevotella intermedia: §Enhanced by the action of proteases§Favors the acquisition of iron, which is an essential nutrient to their metabolism and their survival

•Hemolysin

The following virulence factors are associated with _______: •The brown or black pigment •Collagenase, hyaluronidase, and protease •Hemolysin

Prevotella intermedia

Oral Bacteria A Flashcards

(74 cards)