CAP5-8 Flashcards
Name the 4 stages of a classic bacterial growth phase
Lag
Exponential
Stationary
Decline
Describe the transition from planktonic growth to a biofilm
A developmental pathway, involving:
- biofilm formation
- competence
- motility and chemotaxis
- endospores formation
- scavenging enzymes
- release of antibiotics
- persistor cell state
What is a biofilm
Microbial communities attached to a surface
Spatially Organised in a 3D structure, bacterial cells are enclosed in extracellular matrix, increasing the habitat range of each individual bacteria
Properties of a typical biofilm X4
Cooperation/coordination of behaviour (gene expression)
Structure
Micro environments (from pH to oxygen tension)
Protection (matrix can protect, different cell state can protect)
Name the 5 developmental stages of plaque biofilm
1 pellicle formation
2 attachment of individual bacteria cells
3 growth of individual bacteria (formation of distinct micro colonies)
4 microbial succession and diversification
5 climax community
What does microbial succession in plaque biofilm refer to?
Microbial succession refers to the population shift from a streptococcus dominated plaque to a plaque dominated by Actinomyces
What is quorum sensing?
The process in which single celled organisms monitor their population density by detecting the concentration of small diffusible signal molecules produced by the cells themselves.
What is the signal molecule produced by gram-ves and gram+ves used in quorum sensing?
Gram -ves: N-Acyl Homoserine Lactones
Gram +ves: oligopeptides
What are the two factors important in controlling caries progression, by the ecological plaque hypothesis?
- mechanical cleaning
- some restriction of sugar intake
What is a logical consequence of the specific plaque hypothesis?
Preventive measures targeting specific bacteria eg immunisation
What is a consequence of the non specific plaque hypothesis?
All plaque should be disturbed by mechanical plaque control (tooth brushing)
4 factors contributing to dental caries
Teeth
Plaque bacteria
Sugar
Time
Name the three chemical methods of plaque control
Antibiotics
Antiseptics
Enzymes
Major problems with use of antibiotics in plaque control x4
Disruption of natural flora (C. Albicans)
Resistance
Hypersensitivity
Storage issues
What do antiseptics work on?
Gram positive and gram negative
What is the class of enzymes that is used in chemical plaque control
STAMPs (specifically targetted anti-microbial peptides)
Function of enzymes in chemical plaque control
Used to break off plaque /modify access of nutrients
Downsides of use of enzymes in chemical plaque control x4
Not very effective
Do not store well in toothpastes
Enzymes are very specific
Enzymes are proteins, hence might lead to hypersensitivity
Ideal properties of disclosing agents x6
- non toxic
- does not taste bad ie acceptable taste
- easily removed from mouth after use
- good Colour contrast with teeth and soft tissue
- indicate oldest and most metabolically active areas of plaque
- inexpensive
What is the most commonly used disclosing agent
Erythrosin
Which disclosing agent requires the use of blue/UV lamp to see plaque?
Fluorescin
What does Fluorescin require to work?
Blue /UV lamp
Name 6 antigens of strep mutans
- protein antigens (antigen I/II)
- glucosyltransferase
- glucan binding proteins
- peptidoglycan
- lipoteichoic acid
- serotype specific antigens
What is the replacement theory?
Replacement of pathogenic bacteria by non-pathogenic
