Biofilms - Microbial Ecology of the Mouth

Question 1

what is a biofilm?

Answer 1

matrix enclosed bacterial (or fungal) populations adherent to each other and/or to surfaces or interfaces

Question 2

what are biofilms generally made of?

Answer 2

bacteria

Question 3

what do the bacteria in biofilms produce?

Answer 3

a glue which is important for protecting it from saliva and antibiotics and innate immune response, therefore making the glue an immune defence

Question 4

what are the defining characteristics of the biofilm?

Answer 4

immune defence and very difficult to clinically manage these infection types with an antimicrobial

Question 5

what are planktonic cells?

Answer 5

free floating cells

Question 6

what are the benefits of being a biofilm?

Answer 6

protective environment, co-ordinated cellular events, division of labour, EPS traps nutrients, less energy utilised, survival in numbers, bacteria can sense one another

Question 7

what is needed for a biofilm development?

Answer 7

surface, conditioning film and micro-organism

Question 8

what are the stages of biofilm development?

Answer 8

adhesion, colonisation, accumulation, complex community and dispersal

Question 9

what is the glycocalyx extra-cellular matrix composed of?

Answer 9

exopolymeric substrate

Question 10

what does the glyocalyx extracellular matrix do?

Answer 10

maintains a hydrated environment, helps maintain a tissue-like integrity and provides protective barrier

Question 11

what does the organisation of microcolonies within the glycocalyx extracellular matrix allow?

Answer 11

active diffusion

Question 12

what features of immune resistance does the glycocalyx extracellular matrix give?

Answer 12

blocks phagocytosis, covers complement activation sites on the bacterial surface, inhibits chemotaxis, decreased natural killer cell function, prevents diffusion of bacterial products, immune complexes - frustrated immunity

Question 13

how does the glycocalyx extracellular matrix have antibiotic resistance?

Answer 13

prevents diffusion of antibiotics, acts as ion-exchange barrier, binding charges molecules, thickness and complexity, physiological state of the bacteria, low growth rates, differential gene expression

Question 14

what is dental plaque?

Answer 14

a diverse microbial community found on the tooth surface, embedded in a matrix of polymers of bacterial and salivary origin

Question 15

where is dental plaque found?

Answer 15

at protected and stagnant surfaces, and these are at greatest risk of disease

Question 16

how does dental plaque form part of the defence system?

Answer 16

it helps to prevent colonisation of enamel by exogenous microorganisms

Question 17

what are the 2 different types of caries?

Answer 17

root surface caries and coronal caries

Question 18

name an endodontic infection

Answer 18

root canal

Question 19

what are the 2 periodontal infections

Answer 19

gingivitis and periodontitis

Question 20

where does oral malodour originate from?

Answer 20

dorsal surface of the tongue

Question 21

name 3 mucosal infections

Answer 21

thrush, angular chelitis, denture stomatitis

Question 22

what are the 4 stages of plaque development?

Answer 22

pioneer colonisation, outgrowth, secondary colonisation, climax community

Question 23

what happens in the outgrowth stage of plaque development?

Answer 23

microcolony spread outward and upward

Question 24

what happens in the secondary colonisation stage of plaque development?

Answer 24

pioneers act as substrate, co-aggregation, specific interactions

Question 25

what happens during the climax community stage of plaque development?

Answer 25

polysaccharide production, synergistic metabolic interactions, nutrients, redox potential, oxygen, pH

Question 26

what is the microbial ecology like with a high protein diet?

Answer 26

few acidogenic organisms, more gram-negatives, secondary metabolites - malodour

Question 27

what is the microbial ecology like with a high carbohydrate diet ?

Answer 27

metabolism reduced pH, aciduric organisms thrive, streptococci and lactobacilli