Oral Bacteria A- Exam III Flashcards
The small ribosomal subunit for bacteria is composed to:
16s ribosomal RNA
Around how many nucleotides are present in the 16s rRNA?
1540
How many proteins comprise the 16s rRNA
21 proteins
This has become the gold standard in microbial and taxonomic classification of bacterial species in microbiology:
basing identification on the 16s ribosomal RNA gene sequencing
Why do we use the 16s rRNA for evaluating phylogenetic relationships among microorganisms??
the degree of conservation of genes differs considerably; conserved regions of the gene are identical for all bacteria while the variable regions contain specific sites unique to individual bacteria
The uniqueness of the ____ regions enables taxonomic positioning and identification of bacteria:
variable regions
one of the highest concentrations of bacteria in the body:
biofilm on tooth surface
Colonizing bacteria interact with the ___ on the tooth surface
acquired pellicle
In the formation of dental plaque, bacteria never come into contact with a ___. The tooth surface is coated with an ___.
clean tooth surface; acquired pellicle
Describe the acquired pellicle:
Film deposited on tooth surface composed of:
1. molecules in saliva (predominant)
2. material shed from bacterial cell surfaces
3. polymers from GCF
Once this acquired pellicle is on the surface of the tooth, ___ of bacteria occurs the pellicle surface
passive transport
The initial colonization of bacteria to the pellicle surface is by what bacterial species?
- strep gordonii
- strep oralis
- strep mitis
- strep sanguinis
The bacteria have ___ on the bacterial surface and bind to ___ in the pellicle
adhesins; receptors
Polymers from saliva and bacteria:
pellicle receptors
Once the strep species bind to the pellicle, adhesion is usually ___.
irreversible
Major adhesins of streptococci include:
Antigen I/II
Streptococcus have important adhesins including antigen I/II that also bind:
human salivary glycoproteins , other bacteria & calcium
Once the initial colonizing bacteria are attached to the tooth surface they can become binding sites for additional bacterial species, this is referred to as:
coaggregation
Following the initial streptococcus species that colonize, the additional bacterial species that coaggregate include:
- actinomyces naeslundii
- actinomyces viscosus
- streptococcus gordonii
Through bacterial metabolism through the multiple layers of species, this creates a:
microenvironment
The microenvironment created through bacterial metabolism of the initial colonizing and coaggregation layers of bacteria supports additional species of bacteria including:
- strep mutans
- strep sobrinus
The bacteria are not just binding to the developing biofilm, they are are also:
mutliplying
An important component of the biofilm (especially in the streptococcus species) is:
gluten production
Streptococci produce ____ which are extracellular enzymes:
glucosyltransferases
Streptococci produce glucosyltransferases that are extracellular enzymes that:
polymerize the glucose moiety of sucrose into glucan polymers and other polysaccharides
Extracellular enzymes that polymerize the glucose moiety of sucrose into glucan polymers and other polysaccharides
glucosyltransferases
What do the glucosyltransferases polymerize the glucose moiety of sucrose into:
glucan polymers and other polysaccharides
Branched-chain polysaccharides with alpha 1-6 and alpha 1-3 linkages:
glucans
Glucans are branched-chain polysaccharides containing what linkages:
alpha 1-6 and alpha 1-3
When bacteria cleave sucrose, they can take the resulting glucose and fructose and:
ferment it into acid
Glucans are like ____ (like long polymers) and bacteria both:
cement; produce and bind to them
As bacteria continue to build up and create these cement-like layers, what occurs?
oxygen levels drop
As bacteria continue to build up and create these cement-like layers, and oxygen levels drop, this allows:
the late colonizers to enter into the biofilm and begin to proliferate
Late colonizers include: (category)
obligate anaerobes
Later colonizers include obligate anaerobes such as:
- prevotella melaninogenicus
- prevotella oralis
- veillonella species
We see the drop of oxygen levels in the biofilm especially:
between the teeth and dental gingival crevice
In addition to all of the binding that is occurring to create the biofilm, you will also get some:
detachment of bacteria and colonization of new site
How do bacteria forming the dental biofilm death and colonize new sites?
Some bacteria will shed or degrade their adhesins to facilitate release
Altered properties of bacteria in a biofilm:
- ____ for extracellular polysaccharide synthesis
- Increased ___ to antimicrobial agents
- ____ between closely spaced bacteria
- up regulation of genes
- Increased resistance
- metabolic interacton
Altered properties of bacteria in a biofilm:
up regulation of genes for:
extracellular polysaccharide synthesis (glucan and fructan production)
Altered properties of bacteria in a biofilm:
Increased resistance to antimicrobial agents: (4)
- restricted penetration into biofilm
- inactivation by enzymes
- slow bacterial growth
- expression of novel surface-associated phenotypes
Why would slow growth rate of bacteria in biofilm lead to increased resistance to antimicrobial agents?
Antibiotics rely on bacterial growth
Why would expression of novel surface-associated phenotype led to increased resistance to anti-microbial agents?
This prevents antimicrobial agents from penetrating the biofilm
Describe the metabolic interactions between closely spaced bacteria in the biofilm:
synergistic & antagonistic
A synergistic interaction between closely spaced bacteria in the dental biofilm results in:
degradation of complex nutrients
A antagonistic interaction between closely spaced bacteria in the dental biofilm results in:
bacteriocins (exclude susceptible strains)
What are bacteriocins?
compounds that are antimicrobial and sculpt the composition of the biofilm
The dental plaque eventually reaches ____ which means ____.
microbial homeostasis; stability in bacterial composition
Breakdown of homeostasis alters bacterial composition of the biofilm by:
- reduction in saliva flow
- increased consumption of sucrose
With reduction in saliva flow and increased consumption of sucrose for example, this might lead to:
caries
What is the main bacteria responsible for caries development?
mutans streptococci
Fermentation in the biofilm produces acids including:
- lactic acid
- acetic acid
3 .formic acid
Acid demineralizes the teeth by: (2)
- solubilizes calcium and phosphate (produced from hydroxyapatite)
- gets reprecipitation of calcium when pH increases (becomes less acidic)
Regular snacking on high sucrose food creates:
prolonged acid ennvironment
In a prolonged acid environment , _____ > ____
demineralization > remineralization
____ dissolves slowly but ___ is more easily attacked and colonized by bacteria
enamel; dentin
Because its protein rich, any different bacteria can grow here:
dentin
Once bacteria are in the dentin, the disease rapidly progresses and :
root canal becomes invades and abscesses form
____ is required for the accumulation of mutans streptococci:
sucrose
In addition to sucrose, what else is retried for the accumulation of mutans streptococci?
Glucosyltransferases (GTFs)
Glucosyltransferases are constituitively synthesized by:
mutans streptococci
What is the mutans streptococcal adhesin?
antigen I/II
Thought to be the second event in the formation of dental plaque:
In the presence of sucrose GTFs synthesize extracellular gluons from glucose
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
Thought to be the third event in the formation of dental plaque and eventually results in carious lesions:
lactic acid formation
____ occurs with age and this changes the ___.
gingival recession; microbial homeostasis
When gingival recession occurs, ___ surface of the root is exposed and made vulnerable to bacterial colonization
cementum
60% of individuals over 60 years old have:
root caries
What are the likely pathogens responsible for root caries in elder individuals?
mutans streptococci and lactobacilli
In addition - actinomyceces viscosus & actinomycese naseslundii
Cariogenic bacteria rapidly transport ____ to convert to ___
fermentable sugars; acid
Compared to noncariogenic bacteria, the transport of fermentable sugars/conversion to acid by cariogenic can be described as:
rapid
cariogenic bacteria have multiple ____ including ___.
sugar transporters; PEP-PTS systems
PEP-PTS systems found in cariogenic bacteria are involved with the process of:
group translocation
When the molecule being transported into the cells being chemically altered DURING TRANSPORT:
group translocation
A pathogenic property of cariogenic bacteria is the production of:
extracellular and intracellular polysaccharides
The extracellular polysaccharide produced by cariogenic bacteria include:
glucans & fructans
The intracellular polysaccharides produced by cariogenic bacteria allow for:
intracellular storage- allows for acid production even when sucrose is not available
cariogenic bacteria have the ability to maintain ___ under extreme conditions
sugar metabolism
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
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
Another way cariogenic bacteria are able to tolerate acidic condition is that their bacterial enzymes have a more:
acidic pH optima
In addition to the intracellular environment and acidic pH optima of enzymes, cariogenic bacteria also produce ___ to protect cell contents
acid-stress response proteins
A notable property of noncariogenic bacteria that allows them to survive in acidified environment (due to cariogenic bacteria) is:
alkali production
____ & ____ are major substrates for alkali production via the generation of ammonia (NH3)
urea and arginine
Urea produces ammonia via:
Arginine produces ammonia via:
urease; arginine deiminase
Virulence factors of strep mutans:
Contain ____ which are important for adhering these bacteria to the salivary pellicle
surface antigens I/II
Virulence factors of strep mutans:
They have ___ & ___ that produce sugars polymers in the exterior of the cell
glucosyltransferases & fructosyltransferases
Virulence factors of strep mutans:
___ & ___ that they produce allow the bacteria to hydrolyze the sugar polymers that they create and utilize these in fermentation to end up producing acids
fructanase & dextranase
What are the two hypothesis for the basis of periodontal disease?
- non-specific plaque hypothesis
- specific plaque hypothesis
Hypothesis for basis of periodontal disease that states, the disease is due to the host response to non-specific growth of bacteria on tooth surfaces:
non-specific hypothesis
Hypothesis for basis of periodontal disease that states, the disease is due to a limited number of species which produce biologically active molecules that are pro inflammatory or antigenic
specific plaque hypothesis
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
- traditional view
- based on the complexity of dental place
- mechanisms of generating an inflammatory response
- LPS
Non-specific plaque hypothesis
What does the non-specific plaque hypothesis recommend for treatment?
treatment dictates that flora be suppressed continually or periodically
- based on key illustrative examples including localized juvenile periodontitis and acute necrotizing ulcerative gingivitis
Specific plaque hypothesis
What does the specific plaque hypothesis recommend for treatment?
either
1. locally delivered antimicrobial agents & systemic tetracycline treatment
- antibiotic mouth rinses with oxidizing agents and systemic metronidazole treatment
Contribute to the basic plaque hypothesis, caused by spirochetes and fusobacterium nucelatum, and commonly referred to as Trench mouth:
acute necrotizing ulcerative gingivitis (ANUG)
LJP (specific plaque hypothesis contributer)
localized juvenile periodontitis
Specific plaque hypothesis considers both:
early onset and adult forms of periodontitis
No single bacterial species uniquely involved; more of a poly microbial infection:
specific plaque hypothesis
According to the specific plaque hypothesis, what certain bacteria do we see continuously associated with lesions/periodontal pockets?
- porphyromonas gingivalis
- tannerella forsythia
- treponema denticola
Kinda of a bridge between the specific plaque hypothesis and non-specific plaque hypotheses:
Porphyromonas gingival as “keystone pathogen”
- leukotoxin
- invasins
- bacteriocin
- phospholipase c
These are all virulence factors of:
aggregatibacter actinomycetemcomitans
What immunoinhibitory virulence associated factor is common in aggregatibacter actinomycetemcomitans?
capsular polysaccharide
- Capsule
- Hemolysin
- Leukocidin/Leukotoxin
- Superoxide Dismutase
These are all virulence factors of:
fusobacterium nucleatum
- brown/black pigment
- collagenase
- hyaluronidase
- protease
- hemolysin
These are all virulence factors of:
prevotella intermedia
