3

Question 1

Microbiota

Answer 1

(species of bacteria present)

Question 2

microbiome

Answer 2

(genes that these cells harbor).

Question 3

Streptococci (S. mitis, S. sanguinis, S. oralis, and S. gordonii)

Answer 3

Bind pellicle through surface adhesins
• Provide binding sites for late colonizers (co-aggregation)
• Produce H2O2 (inhibits S. mutans)

Question 4

Veillonella-

Answer 4

metabolize lactic acid

Question 5

Actinomyces-

Answer 5

Binds to pellicle, other early colonizers and late colonizers (co-aggregation)

Question 6

• Fusobacterium nucleatum

Answer 6

Anaerobe (can tolerate 20% O2)
• Co-aggregates with many species
• Removes oxygen (NADH oxidase/peroxidase)

Question 7

Porphymonas gingivalis

Answer 7

Strict anaerobe, asaccharolytic

Question 8

S. sanguinis

Answer 8

• Surface adhesin SsaB binds tooth surface
• Surface adhesins bind other bacteria (CshA/B,Gbp&SspC/D)
• Antagonizes other species
• H2O2- (S. mutans,
Actinomyces ssp.)
 Challisin-like protease-
degrades CSP- mutacin (bacteriocin) production is reduced.
• Reduces inflammation in oral cavity

Question 9

Non-specific plaque hypothesis:

Answer 9

Dental caries results from a perturbation in bacterial populations due to a disruption in the environment rather than a specific bacteria or infectious agent.

Question 10

Streptococcus mutans:

Answer 10

Etiological agent of dental caries
Serotypes- c, e, f, and k based on the rhamose- glucose polysaccharide on cell wall
• 80% of isolates from oral cavity are serotype

Question 11

Acidogenic

Answer 11

ability to metabolism dietary carbohydrates and produce acid

Question 12

Acid tolerant-

Answer 12

ATR (acid tolerance response) more tolerant to acidic environment than commensal bacteria.

Question 13

Glycosyltransferases

Answer 13

extracellular enzymes that form polymers of glucose from sucrose, liberating fructose

Question 14

Glucan binding proteins-

Answer 14

surface proteins that bind glucan

Question 15

S. mutans - Acid tolerance response (ATR)

Answer 15

Up regulation of F1Fo ATPase (pumps protons out of cytoplasm maintaining Δ pH)
• Glycolytic enzymes are more acid tolerant than other species in oral cavity- continues to grow at low pH
• Modifies membrane - less permeable to H+ (protons)

Question 16

Glycosyltransferases

Answer 16

Produce extracellular polysaccharide (EPS) from sucrose
• Absorb to both bacteria and pellicle on tooth surface
• Water insoluble glucan is associated with cariogenic plaque formation- binds everything together (when sucrose is present)

Question 17

Probiotics-

Answer 17

commensal bacteria associate with health

Question 18

S. oligofermentans-

Answer 18

metabolizes lactic acid

Question 19

S. australis-

Answer 19

arginolytic strains- constitutively express ADS - produce NH3 from arginine which can raise the plaque pH. (arginine deaminase –ADS activity).

Question 20

S. gordonii-

Answer 20

produces a protease (challisin) that degrades CSP (signals bacteriocin production) from S. mutans.

Question 21

Bacteriocins-

Answer 21

species specific antimicrobials antagonize growth of target organisms

Question 22

P. gingivalis

Answer 22

Gram-negative rods
• Obligate anaerobic
• Asaccharolytic
• ferments amino acids not sugar
• Requires iron to grow (hemin)
• Keystone pathogen- presence of Pg causes disbiosis, Pg inhibits host immune response to oral flora, allowing some bacteria to take over, leading to further inflammation and bone re-sorption.

Question 23

This bacteria is a late colonizer of dental plaque, is anaerobic but aerotolerant and provides binding sites for other bacteria through co-aggregation.

Answer 23

b) Fusobacterium nucleatum

Question 24

Glucan (EPS) production by S. mutans requires___________.

Answer 24

sucrose

Question 25

Periodontitis is cause by

Answer 25

b) Inflammation | c) Build up of subgingival biofilm