Oral streptococci and caries

Question 1

what are key stone pathogens?

Answer 1

pathogens that are responsible for disease

Question 2

what is the key stone pathogen in caries?

Answer 2

streptococcus mutans

Question 3

are streptococcus mutans gram +ve or -ve?

Answer 3

gram +ve

Question 4

what are the virulence factors for streptococcus mutans?

Answer 4

acidogenic
acidoduric
extracellular polysaccharides

Question 5

streptococcus mutans are acidogenic, what does this mean?

Answer 5

produce acid at a high rate from sugar

Question 6

streptococcus mutans are aciduric, what does this mean?

Answer 6

survive in acidic conditions which can inhibit other bacteria

Question 7

what is the function of extracellular polysaccharides for streptococcus mutans?

Answer 7

for attachment and storage of carbohydrates

Question 8

how is sucrose metabolised by streptococcus mutans?

Answer 8

Glucan transferase metabolises sucrose to produce alpha linked glucans

Question 9

what is the best carbohydrate for polysaccharides? why?

Answer 9

sucrose as it has a high energy bond between glucose and fructose

Question 10

what do glucans do?

Answer 10

enable streptococcus mutans to aggregate (bind to each other)

Question 11

S.mutans will take up a wide range of carbohydrate which makes is more adapted than other species.
give an example of how this can be utilised to kill the bacteria?

Answer 11

xylotol is a carbohydrate that S.mutans will take in but when metabolised is toxic and kills the bacteria

Question 12

name the proteins involved in the attachment of Streptococcus mutans

Answer 12

protein antigens
glucotransferase
glucan binding protein

Question 13

how are protein antigens involved in the attachment of streptococcus mutans?

Answer 13

Allows first binding to pellicle

Question 14

how is glucotransferase involved in the attachment of streptococcus mutans?

Answer 14

Allows aggregation of bacteria (binding to one another) through production of glucans

Question 15

how are glucan binding protiens involved in the attachment of streptococcus mutans?

Answer 15

Binds glucans leading to aggregation

Question 16

explain how vaccines could potentially be made against steptococcus mutans

Answer 16

antibodies could bind to protein antigens and glucan binding proteins to stop them attaching to tooth surface

Question 17

name some other bacterial groups that produce lactic acid

Answer 17

oralis mitis group - streptococcus sanguinis

lactobacilli

actinomyces

rothia denticariosa

Question 18

are lactobacilli gram +ve or -ve?

Answer 18

gram +ve

Question 19

lactobacilli are associated with what kind of caries?

Answer 19

dentinal caries as bind to dentine tubules

Question 20

what can the number of lactobacilli in the oral cavity tell us?

Answer 20

Can also be used to look at carbohydrate intake of an individual: more carbohydrate = higher intake

Question 21

are actinomyces gram +ve or -ve?

Answer 21

gram +ve

Question 22

actinomyces are associated with what kind of caries?

Answer 22

root surface caries

Question 23

name a bacteria that can prevent dysbiosis and this caries

Answer 23

veillonella

Question 24

how does veillonella prevent dysbiosis and thus caries?

Answer 24

uses lactic acid as a substrate it reduces its chances of lowering the pH leading to hard tissue destruction

Question 25

what carbohydrate can prevent caries? how?

Answer 25

Lactose can prevent the aggregation of bacteria through disturbing the extracellular polysacharides

Question 26

what is horizontal gene transfer?

Answer 26

take up DNA from other organisms, some of it can be incorpaorated and allows them to gain a new function

Question 27

remember
An organism can produced different kinds of molecules which favour its survival over other bacteria e.g S.mutans produce lots of acid and survive at a low pH.

Question 28

what is bacteriocin?

Answer 28

a substance released by one bacteria that kills another usually by inducing a metabolic block

Question 29

what are lantibiotics?

Answer 29

an example of small molecules that bacteria can produce to give them a selective advantage

Question 30

what is quorum sensing?

Answer 30

bacteria manage their population density by detecting the concentration of small, diffusible signal molecules produced by the cells themselves.

Question 31

if bacteria find there is a low density through quorum sensing what do they do?

Answer 31

produce molecules for adhesion to focus on colonisation

Question 32

if bacteria find there is a high density through quorum sensing what do they do?

Answer 32

focus on getting nutrient so produce more damaging peptides to take out competitors.