Oral Microbiome and Biofilms (3) Flashcards
What is the group of streptococci which is most involved in dental caries?
Groups Mutans
S. mutans
What group of streptococci favours keratinised surfaces?
Group Sallvarius
S. sallvarius
What group of streptococci favours dental plaque?
Also, name the species
Oralis
species … S. gordonii
What group of streptococci is an early coloniser and produces glucans?
S. oralis
What group of streptococci colonises teeth?
S. sanguis
What group of streptococci favours non-keratinised surfaces?
S. mitis
Describe the Streptococci group Oralis
Early colonisers of pellicle. Some produce IgA proteases.
usually commensal
All may act as opportunistic bacteria
What group of streptococci are important in purulent infections?
Anginosis
Where do S. anginosus cause abscesses?
dental and distant site abscesses
What is a purulent infection?
abscess
usually caused by S. anginosus
What are haemolytic bacteria?
Some bacteria produce hemolysins that damage the membrane of red blood cells.
What diseases do S. pyogenes cause?
causes infections such as strep throat and impetigo.
Is the symbiosis in the oral cavity symbiotic or dysbiotic?
it is dynamic
can shift from symbiosis to dysbiosis
What factors can influence the symbiosis in the oral microbiome?
- disease e.g. diabetes
- genetic differences
- activity of salivary proteins
- salivary flow rates
- innate/ adaptive immune factors
- oral hygiene
- diet
- smoking
- antibiotics/antimicrobial agents
How would you describe the shift from health to disease?
complex and multi-factorial
What do Streptococci eat?
glucose
fructose
sucrose
lactose
galactose
mannose
etc
What is Streptococci favourite thing to eat in the oral cavity?
sucrose is a favourite carbohydrate source
How do bacteria create energy?
metabolise carbohydrates
What is the pellicle made up of?
mucins
acid proline-rich proteins (PRPs)
amylase
albumin
immunoglobulins
glucans
glucosyltransferases (GTFs)
What is a main feature/constituent of the pellicle?
salivary glycoproteins
How much of the acquired pellicle is salivary glycoproteins?
90%
Describe the structure of the salivary glycoproteins
contain acidic sugars (-ve) e.g. sialic acid
highly cysteine rich
What charge do acidic sugars have?
negative
What is the role of proline-rich proteins?
protective
What is the relationship between patients with a high level of PRPs and dental caries?
higher PRPs means a lower level of dental caries
What is the role of alpha-amylase?
digestion
What are the bonds in alpha-amylase?
alpha 1-4 glyosidic bonds
What bacteria use alpha-amylase in the dental pellicle to adhere to surfaces?
receptor for S. gordonii and S. sanguinis
What is the first stage in biofilm formation?
adhesion
What do you call the adhesion between different bacteria?
heterotypic cell-cell adhestion
What do you call the adhesion between the same bacteria?
homotypic bacteria
What do you call the first cell adhering to the pellicle?
cell-substratum adhesion
pioneer species
What is an example of an early collanisers
S. oralis
What are the stages of development in the plaque biofilm?
- Start Clean enamel surface
- 2 s Pellicle formation
- 1 m Pioneer bacteria e.g. Strep. sanguis
- 2 h Microcolonies & extracellular polysaccharide
- > 2 h Biofilm
- 48 h Mature plaque
- 2-7 d Microbial succession and diversification
- > 7 d Climax community.
What is the extracellular polysaccharide?
extracellular matrix in a biofilm
After how long does mature plaque form after brushing?
48 hrs
After how long does a biofilm form after brushing?
2 hours
What is a holobiont?
the host organism and all its symbiotic microbial residents
What is a biofilm?
“Community of microbes characterised by cells that are attached to a surface
or to each other and embedded in a matrix of extracellular polymeric
substances.”
