Periodontal Microbiology Flashcards
Early studies of plaque formation used ________ samples from tooth surfaces but this study was limited by _______.
adhesive tape
time that the tape could adhere to tooth (~3 days)
After adhesive tape studies, plaque was studied by its growth on ________ crowns that were worn for different time periods.
epoxy resin
What results were found through experimental gingivitis models?
People were asked to avoid brushing their teeth for a range of 14-21 days. This study showed that some people are more/less susceptible to forming plaque and disease. Extremes: plaque after only 3 days (4%)….full 21 days and no periodontitis (8%)
What were the two methods for studying microbial environments in early research?
Cultivation and Microscopy
What is the “Great Plate Anomaly?”
There is a difference, in which microbes are seen, between cultivation and microscopy because not all organisms can be cultivated
What is the “We know what we can grow” bias?
All studies focused only on cultivatable species
True or False: Fungi, viruses, and exotic archea may also play a role in oral diseases.
True
The _______ is considered to be shared among groups.
core microbiome
Definition: organized cooperating community of organisms with specific inter-bacterial and host-bacterial interactions.
Plaque Biofilm
How many stages occur in the formation of the biofilm?
Five
The five stages in the formation of a biofilm occur _____, although they do overlap.
sequentially
How were the five stages of biofilm formation determined? Why is this not exactly accurate?
By using a continuous “pool of saliva” they determine 5 stages. However, stages in real life will overlap and occur at different intervals. For instance, the biofilm will be disrupted by mechanical removal
What are the five stages of biofilm formation?
- Free swimming bacteria align, arrange into clusters, and attach (ATTACHMENT)
- Cells begin producing a matrix (GROWTH)
- Cells signal to eachother to multiply and form microcolonies (MATURATION)
- Chemical gradients arise and promote attachment of diverse species (DIVERSIFY)
- Some cells escape to their original form and create new biofilms (PROLIFERATION)
In the attachment stage (1st) of biofilm formation, ______ bacteria adhere to an acquire pellicle.
planktonic
How soon after brushing do we form a new pellicle?
two minutes
When planktonic bacteria adhere to the pellicle, what kind of change takes place?
an alteration in surface charge and free energy
What are two important components of the pellicle?
- salivary glycoproteins
2. antibodies
Bacteria very in _____ ability.
attachment
What is the difference between rapid and slow attachers?
slow attachers have no specific mechanism in place.
Rapid attachers: fimbriae, extracellular polymers, glycocalyx
True or False: Bacterial characteristics remain relatively constant, even after attachment to a pellicle.
False. Characteristics CHANGE after attachment:
- synthesis of new OMPs
- active in cellular growth
What are OMPs and why is their production important following bacterial attachment to the pellicle?
OMPs are “outer membrane proteins” and the immune system hates them. They are a particularly good marker for biofilm virulence.
What is a marker for biofilm virulence?
OMPs (outer membrane proteins)
Most strep. cocci are _____ colonizers.
Primary
_________: cell-to-cell recognition of genetically distinct cell types.
Co-aggregation
_________: interactions between suspended and already adhering micro-organisms.
Co-adhesion
It which mechanism of biofilm growth do you see suspension of all cells and formation of clumps?
Co-aggregation
Co-aggregation is mediated by _______ on one cell and _______ on the other.
Protein (or glycoprotein)
carbohydrates
Co-adhesion of bacteria is particularly influenced by _______ and ______.
Temperature
Lactose
How does temperature influence co-adhesion of bacteria?
No co-adhesion can occur at temperatures greater than 37 degrees
How does lactose influence co-adhesion of bacteria?
increases in lactose will decrease the rate of co-adhesion
In co-aggregation, what is the purpose of bacteria forming clumps? Does it always work?
Clumps stick better to tooth structure because it helps the bacteria to settle in an area. There is an upper limit to clumping because they can become too large to be beneficial
Biofilm maturation (step 3) involves an increase in ______, replication, and _____ formation.
diversity
matrix
Maturation of the biofilm involves ecological ________.
Succession (primary, secondary, tertiary)
Why is F.nuc difficult to grow on saliva?
It is a secondary species, it will only attach if primary species are attached and available
Primary colonizers are gram____, Secondary are gram _____, and tertiary are gram ______.
Primary: Gram + (some gram -)
Secondary: Gram -
Tertiary: Gram -
Secondary species are also known as _______ species because they bind to other bacteria.
Bridge
What is an important secondary colonizer in gingiva?
F.nucleatum
P.gingivalis is a ______ colonizer.
Tertiary
Which colonizers are associated with pathogenicity?
Tertiary
S. sanguis is a _______ colonizer and therefore it _______ be pathogenic in deep periodontal pockets.
Primary
Will not
As the thickness of the biofilm increases, an ________ develops and _______ conditions emerge in the deeper layers.
oxygen gradient
anaerobic
From where does supragingival plaque get its nutrition? Subgingival plaque?
SupraGingival: from dietary products dissolved in saliva
SubGingival: Periodontal tissue and blood
How are bacterial hydrolytic enzymes involved in subgingival plaque?
hydrolytic enzymes breakdown host macromolecules into peptides and amino acids
What are the two components that make up the structure of the biofilm?
Microcolonies (15-20% volume)
Interbacterial matrix
What are the three sources of interbacterial matrix in the biofilm?
- dead bacterial cells
- saliva
- gingival exudate
_______ make up the backbone of the biofilm.
Exopolysaccharides
What are the three layers of the biofilm and the components of each?
Lower: dense layer of microbes, matrix of polysaccharides, steep diffusion gradients
Loose Layer: irregular appearance
Fluid Layer: in motion, provides nourishment through molecular diffusion, sublayer is stationary
The steep diffusion gradient is a part of which biofilm layer?
Lower Layer (only way to penetrate is through mechanical removal, it is not broken via arrestin antimicrobials)
The shape of supragingival plaque’s micro-colonies will depend on ________ force.
Shear
What are the two micro-colon shapes that exist in supragingival plaque?
Towers (mushrooms)
Elongated Colonies that can Oscillate
Towers/Mushrooms are ____ shear force; Elongated colonies are ______ shear force.
Low
High
How does the interbacterial matrix vary?
Gram Positive Matrix - very fibrillar
Gram Negative Matrix - very regular
Interbacterial Carbs - provides energy and skeleton
Dextrans and levans are components of a gram____ matrix.
Positive
Tri-laminar vesicles, filled with _______ and proteolytic enzymes, are components of a gram___ matrix.
endotoxins
Negative
True or False: Gram Negative bacteria is only associated with disease.
False. People can have high concentrations of gram negative bacteria and still be healthy
In subgingival plaque, the _____ forms primary attachment in a similar way that a pellicle forms in supragingival plaque.
Cuticle
How quickly does a pellicle form? What is the source?
Within two mins after cleaning. Forms from salivary proteins
The bacterial layers of subgingival plaque are different near the sulcular epithelium compared with near the tooth. What is the difference?
Near the sulcular epithelium there is no interbacterial matrix. There are more spirochetes and flagellated bacteria (tertiary bacteria sit against epithelium and cause inflammation)
Bacterial _____ is necessary for succession of the biofilm.
collaboration
99% of the time, streptococci are _____ colonizers.
Primary
Strep. cristatus is a _______ species, meaning it can live with or without oxygen.
facultativeP
F. nucleatum is a _________ and binds to strep in order to survive in certain environments.
absolute anaerobe
-binds to survive oxygen
P. gingivalis is a _______ and coaggregation is essential to its survival.
obligate anaearobe
What are three advantages of biofilm living?
- Defense
- Protection from external changes
- Transfer of genetic info and material
How do bacteria communicate and regulate expression of genese within the biofilm?
Quorum Sensing
Within the biofilm quorum sensing, which autoinducer is important in determining whether it is a commensal or pathogenic community?
AI-2
In response to cell density in the biofilm, _______ turn on.
Auto-inducer 1 or Autoinducer 2
Biofilm bacteria are ________ more resistant than planktonic.
1000-1500 times
True or False: Biofilm bacteria grow more slowly.
True
Why do biofilm bacteria grow more slowly?
- express non-specific defense mechanisms
- make more exo-polymers that retard diffusion
How does the slow growth of biofilm affect antibiotics?
They don’t work because antibiotics require high cell turnover
How do exo-polymers retard diffusion?
Ion Exchange - prevents high charge molecules from reaching deeper zones
Extracellular Enzymes - inactivate antibiotics
Are there true oral pathogens?
No, all varieties of bacteria may be present throughout life but you may not have disease. Changes in proportions of bacteria will lead to disease.
How is growth of a microbe in pure culture different from growth in nature?
In nature there is:
- limited nutrients
- poor distribution of nutrients
- lack of optimal temperature
- competition
True or False: Non-contact brushing can remove towers and mushrooms.
True. Shear force/sonic forces
If someone has active perio and needs an impant, what is the standard of care?
Treat the perio FIRST or the implant will be lost
Translocation and transmission of bacteria is a good rationale for _____________.
One-stage, full-mouth disinfection
True or False: Plaque cannot form on implant abutments.
False
_____ will not occur in implants; however, ______ and attachment loss may if microbes deposit in a similar manner to periodontal disease.
Caries
Bone loss
