Oral Bacteria A Flashcards
> _____ different species present in oral cavity
700
less than ____ of the oral bacteria have been cultured
half
_____methods of oral bacteria: collect saliva, tongue blade, scrape from tooth surface, wick fluid from deep pockets (endodontic paper)
sampling
Molecular techniques to ID oral bacteria -often target ______ genes
16S rRNA genes
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
_____
•Biofilmon tooth surface
•One of the highest concentrations of bacteria in the body
Dental plaque
Colonizing bacteria interact with acquired _____
pellicle
T/F: Bacteria never come in contact with a clean tooth surface.
True
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
Initial colonization to pellicle surface is by ____ species
Streptococcus species
What 4 strep sp make up the initial colonizing bacteria to pellicle?
Streptococcus gordonii
Streptococcus oralis
Streptococcus mitis
Streptococcus sanguis(now sanguinis)
______ on bacterial surface bind to receptors in the pellicle.
Adhesins
Adhesins on bacterial surface bind to ______ in the pellicle.
receptors
Pellicle receptors= polymers from what 2 things?
saliva and bacteria
Is adhesion to the pellicle reversible or irreversible?
Irreversible
__________ are important adhesins (Strep)
Bind human salivary glycoproteins, other bacteria and calcium
Antigen I/II
Subsequent attachment of these species and other bacterial species occurs by _______ after initial colonization
coaggregation
_________
•bacteria binding to other bacteria
•additional bacteria bind to early-binding bacteria and to each other
•multiple species
coaggregation
The Important species at the coaggregation stage are what 3 bacteria?
Actinomyces naeslundii
Actinomyces viscosus
Streptococcus gordonii
Once coaggregation occurs, a Microenvironment created that supports additional species
-Bacteria multiply in the developing biofilm
Streptococcus mutans
Streptococcus sobrinus
Streptococci produce _________
•extracellular enzymes polymerize the glucose moiety of sucrose into glucan polymers and other polysaccharides
glucosyltransferases
_______ = branched-chain polysaccharides
Alpha(1à6) linkage
Alpha(1à3) linkage
Glucans
______ are like cement
Bacteria bind to these
Bacteria are bound to each other and to matrix of these
Glucans
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.
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?
- Up-regulation of genes for extracellular polysaccharide synthesis
- Increased resistance to antimicrobial agents
- 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
