Oral Microbiome and Biofilms (3)

Question 1

What is the group of streptococci which is most involved in dental caries?

Answer 1

Groups Mutans

S. mutans

Question 2

What group of streptococci favours keratinised surfaces?

Answer 2

Group Sallvarius

S. sallvarius

Question 3

What group of streptococci favours dental plaque?

Also, name the species

Answer 3

Oralis

species … S. gordonii

Question 4

What group of streptococci is an early coloniser and produces glucans?

Answer 4

S. oralis

Question 5

What group of streptococci colonises teeth?

Answer 5

S. sanguis

Question 6

What group of streptococci favours non-keratinised surfaces?

Answer 6

S. mitis

Question 7

Describe the Streptococci group Oralis

Answer 7

Early colonisers of pellicle. Some produce IgA proteases.

usually commensal

All may act as opportunistic bacteria

Question 8

What group of streptococci are important in purulent infections?

Answer 8

Anginosis

Question 9

Where do S. anginosus cause abscesses?

Answer 9

dental and distant site abscesses

Question 10

What is a purulent infection?

Answer 10

abscess

usually caused by S. anginosus

Question 11

What are haemolytic bacteria?

Answer 11

Some bacteria produce hemolysins that damage the membrane of red blood cells.

Question 12

What diseases do S. pyogenes cause?

Answer 12

causes infections such as strep throat and impetigo.

Question 13

Is the symbiosis in the oral cavity symbiotic or dysbiotic?

Answer 13

it is dynamic
can shift from symbiosis to dysbiosis

Question 14

What factors can influence the symbiosis in the oral microbiome?

Answer 14

1. disease e.g. diabetes
2. genetic differences
3. activity of salivary proteins
4. salivary flow rates
5. innate/ adaptive immune factors
6. oral hygiene
7. diet
8. smoking
9. antibiotics/antimicrobial agents

Question 15

How would you describe the shift from health to disease?

Answer 15

complex and multi-factorial

Question 16

What do Streptococci eat?

Answer 16

glucose
fructose
sucrose
lactose
galactose
mannose

etc

Question 17

What is Streptococci favourite thing to eat in the oral cavity?

Answer 17

sucrose is a favourite carbohydrate source

Question 18

How do bacteria create energy?

Answer 18

metabolise carbohydrates

Question 19

What is the pellicle made up of?

Answer 19

mucins
acid proline-rich proteins (PRPs)
amylase

albumin
immunoglobulins
glucans
glucosyltransferases (GTFs)

Question 20

What is a main feature/constituent of the pellicle?

Answer 20

salivary glycoproteins

Question 21

How much of the acquired pellicle is salivary glycoproteins?

Answer 21

90%

Question 22

Describe the structure of the salivary glycoproteins

Answer 22

contain acidic sugars (-ve) e.g. sialic acid

highly cysteine rich

Question 23

What charge do acidic sugars have?

Answer 23

negative

Question 24

What is the role of proline-rich proteins?

Answer 24

protective

Question 25

What is the relationship between patients with a high level of PRPs and dental caries?

Answer 25

higher PRPs means a lower level of dental caries

Question 26

What is the role of alpha-amylase?

Answer 26

digestion

Question 27

What are the bonds in alpha-amylase?

Answer 27

alpha 1-4 glyosidic bonds

Question 28

What bacteria use alpha-amylase in the dental pellicle to adhere to surfaces?

Answer 28

receptor for S. gordonii and S. sanguinis

Question 29

What is the first stage in biofilm formation?

Answer 29

adhesion

Question 30

What do you call the adhesion between different bacteria?

Answer 30

heterotypic cell-cell adhestion

Question 31

What do you call the adhesion between the same bacteria?

Answer 31

homotypic bacteria

Question 32

What do you call the first cell adhering to the pellicle?

Answer 32

cell-substratum adhesion pioneer species

Question 33

What is an example of an early collanisers

Answer 33

S. oralis

Question 34

What are the stages of development in the plaque biofilm?

Answer 34

1. Start Clean enamel surface 2. 2 s Pellicle formation 3. 1 m Pioneer bacteria e.g. Strep. sanguis 4. 2 h Microcolonies & extracellular polysaccharide 5. > 2 h Biofilm 6. 48 h Mature plaque 7. 2-7 d Microbial succession and diversification 8. > 7 d Climax community.

Question 35

What is the extracellular polysaccharide?

Answer 35

extracellular matrix in a biofilm

Question 36

After how long does mature plaque form after brushing?

Answer 36

48 hrs

Question 37

After how long does a biofilm form after brushing?

Answer 37

2 hours

Question 38

What is a holobiont?

Answer 38

the host organism and all its symbiotic microbial residents

Question 39

What is a biofilm?

Answer 39

“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.”