Oral Bacteria

Question 1

The oral cavity is dominated by this bacteria:

Answer 1

Streptococci
(S. Mitis- all of mouth.
S. Sanguinis and S. Gordonni- tooth surface)

Question 2

Early (pioneer) oral colonizer. Binds pellicle thru surface adhesins, provides binding sites for late colonizers (co-aggregation), produces H2O2 (inhibits S. mutans)

Answer 2

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

Question 3

Early (pioneer) oral colonizer. Metabolizes lactic acid

Answer 3

Veillonella

Question 4

Early (pioneer) oral colonizer. Binds to pellicle, other early colonizers and late colonizers (co-aggregation)

Answer 4

Actinomyces

Question 5

Late colonizer of oral cavity. Anaerobic but aerotolerant, co-aggregates, removes oxygen

Answer 5

Fusobacterium nucleatum

Question 6

Late colonizer of oral cavity. Strict anaerobe, asaccharolytic

Answer 6

Porphymonas Gingivalis

Question 7

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

Answer 7

Non-specific plaque hypothesis

Question 8

Etiological agent of dental caries. Mainly Serotype C in oral cavity.

Answer 8

Streptococcus Mutans

Question 9

Virulence factors of Streptococcus Mutans:

Answer 9

1. Acidogenic (metabolizes carbs -> acid production)
2. Acid Tolerant- more tolerant than commensal bacteria
3. Glycosyltransferases- enzymes that form polymers of glucose from sucrose, liberating fructose
4. Glucan binding proteins

Question 10

Three GTF (Glycosyltransferase) enzymes of S. mutans:

Answer 10

1. GtfB (Gtfl)- water insoluble glucan, alpha 1,3 linked
2. GtfC (GtfSl)- both water insoluble glucan alpha 1,3 linked and water soluble alpha 1,6-linked glucose
3. GtfD (GtfS)- water soluble alpha 1,6-linked glucose

Question 11

Probiotics used to treat dental caries:

Answer 11

1. S. Oligofermentans- metabolizes lactic acid
2. S. Australis- raises plaque pH
3. S. Gordonii- Produces protease that degrades CSP

Question 12

Glucan (EPS) production by S. mutans requires ____

Answer 12

Sucrose

Question 13

Bacterial species most commonly associated with Periodontal Disease:

Answer 13

1. P. Gingivalis (Porphyromonas Gingivalis)
2. Tannerella Forsythia
3. Treponema Denticola

(All anaerobes, all part of Socransky’s Red Complex)

Question 14

P. Gingivalis:

1. Gram stain?
2. Oxygen Tolerance?
3. What does it ferment?
4. Why is it a keystone pathogen in periodontal disease?

Answer 14

1. Gram-negative
2. Obligate anaerobic
3. Amino acid (not sugar)
4. Causes disbiosis (inhibits host immune response, allowing bacteria to take over)

Question 15

Periodontitis is caused by _____

Answer 15

Inflammation and build up of subgingival biofilm