Bacteria Flashcards
bacterial complexes
the composition of the different color coded complexes is based on the frequency with which the organisms are encountered together
blue and purple complex
what are these considered?
consists of gram-positive cocci and rods
PRIMARY COLONIZERS
yellow complex
is compromised of gram-negative faculative cocci
green complex
contains gram-positive and negative rods and cocci- biut NON-motile species present
orange complex + importance
demonstrates a higher concentration of gram-negative rods and cocci, with some motile species present
what we see with perio patients
red complex and importance
is EXCLUSIVELY gram-negative , MOTILE anaerobes
what we see with perio patients
bacteria present in the red complex
P. gingivalis
T. denticola
T. forysthensis
bacteria present in green complex
A. actinomycetemcomitans
red and orange complex?
implicated in perio patients with higher
- patients will develop symptoms of perio in these complexes
you dont want these
will you ever find a patietn with just red and orange complex?
NO - they need the primary colonizers to adhere
transition from health to disease?
gram - positive, aerobic, non-motile —> gram-negative, anaerobic, motile
where does anaerobic bacteria thrive?
sulcus – attachment apparatus here
gingivitis association with complexes?
early colonizers are associated with mild, gingival inflammation (gingivitis)
shear mass of plaque is more geared toward what hypothesis?
non-specific plaque hypothesis
what does non-specific theory represent?
gingivitis
plaque hypothesis of periodontitis?
introduction of specific bacteria
-ecological plaque hypothesis – triggers some species to become more aggressive
late colonizers implication?
“red complex” – are associated with severe periodontal inflammtion
how does bacteria cause disease?
steps..7 total
when this sequence occurs…
- acquisition
- adherence or retention
- initial survival
- prosperity and long-term survival
- avoidance of elimination
- multiplication
- elaboration of virulence factors
vertical transmission
occurs at birth from parental and other environmental sources
endogenous organisms
those organisms already present within the host when the disease is developed
exogenous organisms
those acquired from other individuals or the environment which may initiate the disease process or enable its progression
main microbes in oral cavity and amount
up to 10^3 bacteria per MILLIMETER. types - streptococci - staphylococci - Cornyebacteria - Neisseria, -LActobacilli, - Candida -- note this is a fungus
important colonizer on the surface of teeth?what aids the growth of lactobacilli?
Streptococcus mutans is an important colonizer on the surface of the teeth (especially in those with a high sucrose diet)
when sugar is broken down – lactic acid— lowers pH in mouth and aids growth
- usually above process done by streptococcus
streptococcus mutans importance in oral cavity and location?
mostly colonizers on the surface of the teeth and are more prevalent in patients that have a high sucrose diet and will break down this sugar and lactic acid will be produced– attacks surface
describe environment of sulcus
crevices – microenvironements with LOW levels or absnence of oxygen, thus favoring these anerobic microbes
normal oral flora
essential for life
- collectively describes the various microbial types frequently found by culture or microscopy on the skin and mucous membranes and certain body cavities in normal healthy individuals
- *****species and amount of flora vary in different areas of the body and at different stages of development
it is the foreign microbes that were responsible for infecting animals and humans and causing disease
when is oral cavity sterile?
during intrauterine life and at birth
within 4-12 hours of flora in development
lacotbacilli and streptocicci
first feeding implication on flora?
colonized from environment
see streptococcus salivarius, staphylococci, Niesseria, Moraxella eatarrhalis
what happens when switch to solid food?
microflora similar to parents
flora when teeth appear?
nondesquamating surface (so now a surface to attach to)
streptococci mutans, streptococcus parasanguis
flora in crevice area?
anaerobic species, yeasts
flora at puberty?
bacteroides, spirochetes
complexity of flora as you get teeth and change diet?
becomes more complex and more anaerobes become established
caries bacteria?
lactobaccilli
older age / loss of teeth effect on normal flora
flora becomes less complex
- less lactobacilli, strept mutans and yeast
when can you see an increase in yeast?
in complete dentures, and can also get an increase in strept mutans
bacterial flora around a dental implant?
bacterial flora around dental implants is similar to that found around natural teeth
commensals?
describes the microorganisms present in the oral cavity
physiological factors in a given area that effect flora?
Temperature
Moisture
Presence of nutrients
3 main benefits of the normal oral flora
- occupy available colonization sites which makes it more difficult for other microorganisms (nonindigenous species) to become established (protective)
- host nutrition through the synthesis of vitamins and by contributing to immunity by inducing low levels of circulating and secretory antibodies that may cross react with pathogens
- production of fatty acids, peroxides, and bacteriocins which can exert microbial antagonism against other nonindigenous species)
what do early colonizers produce? what does this allow/form?
EPS (exopolysaccharides) which will enable attachment / adherence
–> that will glue the cells to the surface and eventually form the biofilm matrix
EPS composition?
Mainly polysaccharides but can also include proteins, nucleic acids, and plymeric lopiphilic compounds
represents the major structural component of biofilms
biofilm function?
The development of a biofilm – ability for the prosperity/ long term survival
Responsible for the interaction of microbes with each other as well as with interfaces
bacteria in the biofilm are protected in this environment
think of these as ‘bacterial cities’
can get access to food and get rid of wastes
then ‘live in harmony’ with neighbors
describe initial adherence between bacteria and non-living surfaces
mediated by non-specific – HYDROPHOBIC interactions
describe adhesion to living surfaces
accomplished through specific molecular docking mechanisms
adhesion/ retention during biofilm growth
mediated by specific ADHESINS – or cell surface modifications such as PILLI OR FIMBRAE
coaggregation
development of mixed-species biofilms — genetically distinct bacteria together via specific molecules
gingival crevicular fluid implication on survival of bacteria?
aids in initial survival
- this fluid is a rich source of nutrients such as essential energy sources like GLUCOSE AND IRON.
- also contains host-derived elements which can decrease bacterial survival such as antibodies and complement
LPS is so important because?
essential for gram-negative bacteria to live
one of the most toxic substances we can administer to someone
3 main
recognized by the AAP
NEED TO MEMORIZE
- Porphymonas gingivalis
- Tannerella forsythia (bacteriodes forsythus)
- Aggregatibacter (aa)
T. denticola – overwhelming evidence
associated with bacteria chronic adult periodontisits
p. gingivalis is most known
3 main
recognized by the AAP
NEED TO MEMORIZE
- Porphymonas gingivalis
- Tannerella forsythia (bacteroides forsythus)
- Aggregatibacter (aa) actinomycetemcomitans
T. denticola – overwhelming evidence
p. ging. host invasion factors and produce?
aggressive and produce things that are toxic to host
acitvely attacking host tissues
produce gingipains
Porphymonas gingivalis- describe colonization site
major site is subgingival pocket
- surface adhesion molecules
- some mobility
evidence that this causes chronic periodontitis
Tannerella forsythia (bacteroides forsythus)
difficult to obtain from host (difficult to culture)
- a gram - filament shaped, non-motile, non-pigmented oral bacterium
- overall not well characterized
conversion of periodontally healthy sites into diseases sites and associated with ‘refractory’ periodontitis
Tannerella forsythia (bacteroides forsythus)
difficult to obtain from host (difficult to culture)
- a gram - filament shaped, non-motile, non-pigmented oral bacterium
- overall not well characterized
conversion of periodontally healthy sites into diseases sites and associated with ‘refractory’ periodontitis
refractory periodintitis
perio tx not working - like due to smoking and likely harbored larger amounts of Tannerella forsythia
Aggregatibacter (aa) actinomycetemcomitans assoicated with?
AGGRESSIVE LOCALIZED PERIO
aggressive localized perio main bacterium
Aggregatibacter (aa) actinomycetemcomitans
what is unusual about Aggregatibacter (aa) actinomycetemcomitans complex/ profile
IT IS GREEN – not in the red orange complex
what is unusual about Aggregatibacter (aa) actinomycetemcomitans complex/ profile
IT IS GREEN – not in the red orange complex
- growth is enhanced by the presence of CO2
what does Aggregatibacter (aa) actinomycetemcomitans produce?
LEUKOTOXIN – so it actively attacks the white blood cells
virulence factors of Aggregatibacter (aa) actinomycetemcomitans
major one is the leukotoxin
T/F the oral flora is the usual cause of various oral diseases in humans, included abscesses, dental caries, gingivitis, and periodontal disease
TRUE
can even gain entrance into deeper tissues like bone, lung, brain, or extremities
Quorum sensing
the ability to respond to products or signals from other biofilm organisms, or the host, and to use these to grow and prosper
- contributing to the prosperity and long term survival of the bacteria
what do you see in mature biofilms?
NICHES – complex architecture that provides niches with different physicochemical conditions, differing in oxygen availability, in concentration of diffusible substrates and metabolic side products, in pH, and in the cell density
- cells in different regions of biofilm can exhibit different patterns of gene expression
-
mixed species biofilms?
can contain niches with distinct groups of bacteria having metabolic cooperation
- dynamic community with sharing of genetic matiera, competing, and cooperating
key to avoidance of elimination? additional components to this
acterial capsules - facilitates this
+ some can undergo genetic drift and shift
so antigens mutate and antibodies can no longer recognize and bind to them
+sequester themselves within the host tissues
use of antibiotics in chronic periodontitis?
counter- productive because by the time the active agent has penetrated the biofilm - its concentration is too low to be effective and resistant strains of bacteria can emerge
multiplication for organisms? implication on survival?
essential for longer term survival
the pathogens need to reach a certain critical mass within the subgingival biofilm in order to survive
- once this level is reached further multiplication beyond a certain threshold is required for disease to occur
three categories of virulence factors
- enzymes
- metabolic waste products
- toxins
definition of virulence?virulence correlates to what?
“full of poison”
- molecules produced by a pathogen that SPECIFICALLY cause disease, or that influence their host’s function to allow the pathogen to thrive
- ability of bacteria to cause disease in general terms of
1. # of infecting bacteria
2. route of entry into the body
3. effects of host defense mechanisms
4. intrinsic characteristics of the virulence factor
- ability of bacteria to cause disease in general terms of
an organisms ‘power’ o produce disease
these are essential for the production of disease
virulence factors are typically what structure?
coded for by?
proteins or molecules synthesized by enzymes of bacterial origin
proteins coded for by genes in chromosomal DNA bacteriophage DNA or plasmids
virulence factor that is ‘constitutive’ vs?
expressed all the time vs others under specific environmental signals
general methods by which pathogens cause disease
- adhesion
- colonization
- invasion
- immune response inhibitors – like producing proteins that bind to host antibodies
- toxins – proteins made by bacteria that poison host cells
what allows for adhesion and colinixation
- fimbriae
- capsule
- microbial antagonisms/ synergy
action of hyaluronidase
increases tissue permeability
action of phospholipase A or C
induces prostaglandin - mediated bone resorption
neurominidase action
enzyme that facilitates tissue spread of bacteria
catalase action
decreases PMN peroxidase
fibronylisis action
inhibits healing, allows tissue spread of bacteria
what is responsible for odor and taste in periodontal disease
metabolic products of bacteria like
- hydrogen sulfide
- ammonia
- indole
- acids
exotoxins
SOLUBLE PROTEIN EXCRETED BY A PATHOGEN
- may be secreted or may be released during lysis of the cell
- both gram negative and gram positive bacteria can produce these
causes damage to the host by destroying cells or disrupting normal cellular metabolism
endotoxin definition?
differ from exotoxin?
in perio disease, endotoxins do what?
potentially toxic, natural compounds found inside pathogens
unlike an exotoxin – IS NOT SECRETED IN SOLUBLE FORM by live bacteria, but is a structural component in the bacteria which is released mainly when bacteria are lysed
in perio the endotoxin will
- cause tissue damage
- amplify the inflammatory response
LPS in what? consists of ?
found in the OUTER MEMBRANE OF gram negative bacteria
- ENDOTOXIN - that can elicit a strong immune response
consists of lipid A and a polysaccharide (O-antigen) side chain joined by a covalent bond
the core is attached to lipid A
LIPID A is the key in the toxicity
what do the the toxins stimulate in periodontal disease?
a chronic inflammatory response – which the body in essence turns on itself – attachment broken down and the epithelial attachment migrates APICALLY – forming pockets that are further colonized by bacteria
what about P gingivalis is associated with eading/modulating the host response?
multiplying?
damaging and spreading?
Modulating –> Ig and complement proteases, LPS, capsule
Multiplying –> proteinases, hemolysins
Damaging host tissues and spreading –> proteinases - GINGIPAINS - collagenase, trypsin-like activity, fribrinolytic
metabolic end products of p gingivalis?
include butyrate, propionate, and have low molecular weights which allows them to easily penetrate periodontal tissues and disrupt the hose cell activity
Virulence of Tannerella forsythia
Virtually unknown
- proteolytic enzymes, trypsin-like enzymes
- sialidase (Neuraminidase)
T.denticola?
commonly associated with periodontal disease with the other three
P. gingivalis
AA
Tannerella forsythia
spirochetes
gram negative, anerobic, spiral, highly motile
associated with necrotizing periodontal disease and increased number of perio pockets
T. denticola is a common in diseased, SUBGINGIVAL SITES **
Do periodontal bacteria physically invade host tissue in vivo?
controversal BUT NECROTIZING PERIODONTAL DISEASES has been comfirmed – invasion of spirochetes in NUG and NUP
