2. Biology of Dental Plaque II Flashcards
Numerous Distinct Microenvironments Within Biofilms
• Who came up with biofilm: \_\_\_\_ (Bosman, Montana) • Attachment of diff species of bac, as thickness of biofilm increases, changes in availability of nutrients: ○ Bathed by saliva - contains \_\_\_\_ - which is a carbohydrate; and proteins (if the bacteria are proteolytic) ○ Not all bacteria use carbohydrates, some are fermentative, some are proteolytic ○ Initial bacteria that bind are \_\_\_\_ bacteria • As biofilm gets thicker, there is a gradient for \_\_\_\_ • As gets thicker, avail of \_\_\_\_ decreases - getting to such a low level, anything that requires O2 won't do well • May be changes in \_\_\_\_ (\_\_\_\_ organisms will drop the pH) • Based on depth of plaque, as you go deeper in plaque there is a drop of O2 - in central mass there is virtually none - either \_\_\_\_ or \_\_\_\_ • Under diff nutrient avail - high carbs, there's a gradient; or can be in oxygen - in middle will be \_\_\_\_
Dr. Costaton sugar carb-loving carbs O2 pJ fermentative anaerobic facul. anaerobe fermenters
Primitive Circulatory System of a Biofilm
• Coral reef ○ Release ink on one side, as it disperses through, the ink will diffuse through all the channels ○ Will initially be dispersed uniformly • Channels are the "vessels" • Interactive network that affects different sites, and it is \_\_\_\_ • But bacteria that are close, it will be a \_\_\_\_ ○ Within the microenvironments, living right next to each
unidirectional
bidirectional
Primitive Circulatory System of a Biolfim
* Arrows - using carbohydrates, release \_\_\_\_ that affects what's happening downstream * What happens on one side, will have manifestations what's happening \_\_\_\_ (complete opposite of LV analogy) * Symbiotic, or mutualistic, or commensal, or antagonistic
acid
downstream
Metabolic Interactions within Oral Biofilms
The interactions can be commensal, synergistic, mutualistic or antagonistic
• Lactate (from carbohydrates from \_\_\_\_) can serve as GF for other organisms (\_\_\_\_) ○ Need these organisms present first ○ \_\_\_\_ relationship ○ Remember this! • Continues to build upon itself • Streptococcal that are \_\_\_\_, use oxygen, decreases the amount, and supports anaerobic organisms - \_\_\_\_, and \_\_\_\_ (strict anaerobe)
streptococcal vionella commensal facultative fusobacterium nucleatum p. gingivalis
Resistance to Mechanisms of Host Defense and Antibiotics
• What types of immune is important in removal of EC infections ○ \_\_\_\_ - IgA - prevent bacterium binding to \_\_\_\_, or can bind directly and activate \_\_\_\_ (IgG, IgM), and \_\_\_\_ acts as opsonin ○ Do neutrophils need Ab? No - can recognize presence by \_\_\_\_ and \_\_\_\_ on cells • Immune system has access to bugs in saliva, but to those deep in biofilm they are inaccessible • In biofilm, express \_\_\_\_ that allows to evade detection by immune system ○ Acts differently in \_\_\_\_ • Presence of biofilm and the matrix protects the bugs from immune and innate mechanisms of immunity • Green = antibiotic ○ Cxn in solution is high - \_\_\_\_ bugs are exposed to high cxn of antibiotic - die ○ As biofilm gets larger, and matrix develops, bugs in deeper parts are exposed to low cxn - they begin to become \_\_\_\_ or \_\_\_\_ due to low levels (immune inhibitory cxn?) § Resistance: selection of the bacteria that can evade the antibiotics
antibodies
surface
complement
C3b
MAMPs
DAMPs
genes
planktonic/biofilm
planktonic
resistant
unaffected
Resistance to Mechanisms of Host Defense and Antibiotics
• Living in biofilm alters geno/phenotype - become more apt to become \_\_\_\_ • Some orgs that grow at \_\_\_\_ - won't be affected by antibiotic • \_\_\_\_ - tolerate antibiotic, state that are unaffected (growth at slow rate) ○ When antibiotic that is no longer present, it will replenish the pop with \_\_\_\_ type • Transfer of genes, that transfers \_\_\_\_ - associated with how bugs live in biofilm • Bugs in biofilm are more resistant to antibiotics - clinical significance: don't use antibiotics to treat periodontitis, but when we do (17 yo with rampant bone loss) in cases with patients with a lot of bacteria; scaling and root planing (under ST to get tartar and biofilm off) in conjunction with antibiotics; do SRP \_\_\_\_, then do \_\_\_\_ ○ Disrupts biofilm, puts bugs in \_\_\_\_ state, where antibiotics can do their job ○ Direct clinical representation of this science
resistant
slow growth
persistors
resistant
resistance
first
antibiotics
planktonic
Interspecies Bacterial Communication within Biofilms
Mechanisms include:
physical interaction
physiological interactions
- metabolic cooperation/antagonism
DNA-mediated interactions
- genetic exchange
microbial intercellular signaling
- contact-dependent signaling
- qurom sensing• Bacteria can communicate
• Metabolic interactions
○ Cooperation/antagonism
• Quorum sensing; bacterial equivalent of ____ signaling
• Bacteriosin
○ Bacterial toxin that can affect ____ cells
cytokine
prokaryotic
Quorum Sensing:
A Mechanism of “Communication” Between Bacterial Cells
A process whereby small signaling molecules produced by bacteria are used by the cells to monitor the ____ of their population.
Typically, results in altered ____ expression and a subsequent change in bacterial “behavior” including increased ____.
• Bugs of \_\_\_\_ species or \_\_\_\_ species • As density gets higher, it would be beneficial for a bacterial cell to slow down process to make it favorable for themselves • VP - ability of bacterium to cause \_\_\_\_ ○ Deleterious to our survival, but beneficial to the \_\_\_\_
density
gene
virulence potential
same
different
disease
bacteria
Quorom Sensing
Cell density-dependent signaling system mediated by molecules known as ____ that are constitutively produced by bacteria during their growth.
Upon reaching a ____ concentration, binding of autoinducers followed by activation or repression of target ____.
The threshold concentration is reached only when cells are at a high ____; the bacteria sense that the population has reached a critical mass or ____.
Allows bacteria to display a ____ response that benefits the population.
* Release of signaling molecule - some affect same species, or some will affect other species - as long as they have the \_\_\_\_ * Can alter gene expression - can alter the overall behavior - slowing proliferation, resulting in a nutrient source won't be depleted and the bacteria will have more to eat
autoinducers threshold genes density quorum
“unified”
receptor
Quorum Sensing
• Types of behaviors that can be altered ○ \_\_\_\_, competence, \_\_\_\_, antibiotic production (toxin that one bug can produce to inhibit another), \_\_\_\_ (movement within the biofilm), and ability of bugs to form a \_\_\_\_.
virulence
conjugation
sporulation
biofilm
The EPS Matrix of Bacterial Biofilms
Composed of extracellular polymeric substances including ____, proteins, lipids and ____.
The contents of the EPS matrix are derived from ____, saliva and/or gingival crevicular fluid and the composition is highly variable depending upon the ____ of the biofilm.
- proteins, lipids, carbohydrates, extracellular DNA
- inorganic molecules
- ____, fungi, viruses, ____ - remnants of host cells• Spaces between the bacterial cells: EPS matrix
• Mainly produced by bugs in the biofilm
• GCF - liquid that is within the sulcus, that is derived from ____
○ Bacteria growing sub-gingivally, some of their ECM may be composed of proteins from ____
• ____ - may or may not be bacteria
polysaccharides
extracellular DNA
bacteria
microbial constituents
mycoplasma
protozoa
serum
GCF
mycoplasma
The EPS Matrix of Bacterial Biofilms
• Facilitates \_\_\_\_ of bacteria to substrate • Facitilates \_\_\_\_of additional orgs to biofilm • Bridging of bugs to species (\_\_\_\_) • Serves as \_\_\_\_ that holds the cells together ○ Reinforces \_\_\_\_ structure of biofilm
adhesions attachment aggregation cement 3d
The EPS Matrix of Bacterial Biofilms
• Do not memorize all of these • Can be a source of \_\_\_\_ to the bugs • Source of \_\_\_\_ information ○ EC DNA in EPS • \_\_\_\_ barrier ○ Relative to antibiotics and host immune system • Absence of this structure, the biofilm will not exist; NECESSARY FOR SURVIVAL OF \_\_\_\_
nutrients
genetic
protective
biofilm
Phases of Bacterial Biofilm Formation
The very first event in the formation of a bacterial biofilm is ____ of the surface onto which the bacteria will attach.
This is followed by: Phase 1: \_\_\_\_ Phase 2: \_\_\_\_ Phase 3: \_\_\_\_ Phase 4: \_\_\_\_ Phase 5: \_\_\_\_
"conditioning" initial attachment irreversible attachment growth maturation dispersal
Phases of Bacterial Biofilm Formation
Lag - ____
Log - ____
Stationary - ____
Death - ____
* Lag - early phases of attachment * Once attaches - proliferate * Cxn of cells is as high as it gets (nutirents, quorum sensing, competiton for mebtaolites) * Maturation - of the ECM * Depletion of nutrients, the biofilm falls apart and bugs fall into the \_\_\_\_ environment
attachment growth maturation dispersal fluid
A Few Basic Concepts About the Formation of Dental Plaque
- Dental plaque is a ____ biofilm the formation of which is a highly ____ process that gives rise to distinct microbial populations within its structure.
multispecies
ordered
A Few Basic Concepts About the Formation of Dental Plaque
- The specific bacterial organisms found in various types of plaque is dependent upon the ____ factors under which the plaque is developing.
- Plaque formation is a ____ process that is driven by constant ____ within the dentogingival environment and the plaque itself.
environmental
dynamic
ecological changes
Determinants of the Microbial Microenvironment 1. Host Factors: • \_\_\_\_ • gingival crevicular fluid (GCF) • \_\_\_\_ • oral hygiene habits • \_\_\_\_ • numerous others
• GCF - derived from \_\_\_\_ - contains proteins ○ \_\_\_\_ orgs • Saliva contains what you eat, and rich in carbohydrates ○ \_\_\_\_ bugs
saliva diet medical history/medications serum proteolytic carb-loving
Determinants of the Microbial Microenvironment 2. Bacterial Factors: • \_\_\_\_ • metabolic characteristics - oxygen requirements - preferred source of nutrients • production of toxins (\_\_\_\_) • coaggregation • factors affecting the \_\_\_\_
• Adhesins - critical to formation of \_\_\_\_
adhesins
bacteriocins
host response
dental plaque
Determinants of the Microbial Microenvironment
Potential Nutritional Interactions Between Plaque Bacteria (“____”)
food chains
Determinants of the Microbial Microenvironment 3. Local Physicochemical Factors: • pH • \_\_\_\_ (oxygen potential) • temperature • \_\_\_\_ availability
redox potential
nutrient
Determinants of the Microbial Microenvironment
• Cementum is apical to enamel ends • Soft tissue is attached to teeth - one component is \_\_\_\_, and the other is the \_\_\_\_attachment ○ JE/SE is only histologically seen • Apical to oral epithelium, tissue above red line is alveolar mucosa ○ Big histological difference: OE is \_\_\_\_, and AM is \_\_\_\_ ○ OE is bound to underlying bone, but AM moves (has a large number of \_\_\_\_ structures) ○ Structure that divides these two is the \_\_\_\_ • Probe slides into gingival sulcus (SE on lateral wall, tooth on other lateral wall and JE at the base) • Connective tissue attachment - collagen fiber bundles that impregnate in the cementum, covering the root of the tooth, that anchor the ST to this tooth • Distance between bone and base of JE is 2mm • With gingivitis there are changes: ○ Inflam cells, and disruption of JE and SE ○ All the tissue looks larger - \_\_\_\_ reaction in CT, BV dilate, and movement of fluid inducing edema - why it looks erythematous, swollen, etc. • Environment changes - deeper - living in GCF that has \_\_\_\_ from an inflam reaction, and the \_\_\_\_ cxn is much different (from the saliva, on the outside)
JE collagen fiber keratinized non-keratinized elastic MEJ inflammatory protein oxygen
Determinants of the Microbial Microenvironment
• With periodontitis: ○ Enviornmentally very different in the \_\_\_\_
periodontal pocket
Stages of an Infection
* Microbial infections dvelop * \_\_\_\_ first * Prolfieration, and invade * Induce \_\_\_\_ reaction * If inflam reaciton doesn't eliminate, then an \_\_\_\_ immune response
In a tooth…
• Enamel gets ____, bac attach to it
• As biomass increases in complexity, orgs start to inhabit biomass
• Can invade epithelial cells and get into gingival conn tissue
• And then an inflam reaction (____), and under adaptive immune response (develops into ____)
attachment
inflam
adaptive
conditioned
gingivitis
periodontitus
The Acquired Pellicle
1. Essentially ____ organic film that is deposited on teeth and facilitates ____
cell-free
plaque initiation
