Lecture 4 - Normal Oral Flora

Question 1

T or F, There are few true obligate aerobes in the mouth

Answer 1

True

Question 2

The vast majority of bacteria in the mouth are one of what 3 things?

Answer 2

1. Facultative
2. Microaerophilic
3. Anaerobic

Question 3

Supragingival plaque biofilm is primarily made of what types of bacteria?

Answer 3

Facultative and microaerophilic bacteria

Question 4

What types of bacteria make up most of the subgingival plaque biofilm

Answer 4

facultative and anaerobic bacteria

Question 5

Deep perio-pockets yield very high concentrations of what kind of bacteria?

Answer 5

Strict anaerobes

Question 6

What 3 supragingival plaque biofilm bacteria cause dental caries?

Answer 6

1. Strep. mutans
2. Lactobacillus sp.,
3. Actinomyces sp.

Question 7

What types of subgingival, plaque biofilm bacteria cause periodontal disease and endodontic infections?

Answer 7

Gram negative, facultative & anaerobic rods

Question 8

T or F, Only gram-positive bacteria are associated with Gingivitis?

Answer 8

False, Gingivitis is generally caused by a ‘simple’ overgrowth of plaque biofilm, and thus both gram-positive and gram-negative bacteria are associated with it

Question 9

Describe streptococcus (6)

Answer 9

1. Viridans group and species
2. Mostly alpha-hemolytic = produce green coloring on blood agar
3. Facultative
4. Produce ECM
5. Sugar-substrate = Saccarolytic
6. Many tolerate low pH well

Question 10

Name the “good” G+ cocci and “bad” G+ cocci?

Answer 10

Good: S. anginosis, S. mitis, S. salivarius
Bad: S. mutans

Question 11

S. mutans are found mainly where?

Answer 11

in Plaque

Question 12

S. mutans:

Answer 12

1. Mainly found in plaque
2. Produces insoluble polysaccharides
3. grows well at low pH
4. produces large amounts of lactic acid (dental caries)

Question 13

What two groups of S. mutans are found in humans?

Answer 13

S. mutans and S. sobrinus

Question 14

Which G+ cocci is found in plaque, mucosa, and respiratory tract, a common cause of purulent (= pus-forming) disease

Answer 14

S. angionosis

Question 15

Which two G+ cocci are sworn enemies and why?

Answer 15

S. mutans and S. mitis.
- They both secrete products that the other group doesn’t like. Usually, when one is in high concentration, the other will be at low concentrations.

Question 16

Which G+ cocci is a pioneer species on teeth?

Answer 16

S. mitis

Question 17

S. mitis:

Answer 17

1. Pioneer species on teeth

2. Makes insoluble and soluble polylsaccharides

Question 18

Most important species of S. mitis group

Answer 18

S. sanguinis (remember, pioneer species of teeth)

Question 19

Which G+ cocci colonizes much of the mucosal surface, especially tongue, major source of bacteria in saliva, and generally considered a “good guy”

Answer 19

S. salivarius

Question 20

Which species is most important in S. salivarius?

Answer 20

S. salivarius

Question 21

Enterococcus:

Answer 21

1. Opportunist infections
2. Able to survive harsh environments (significant nosocomial problem)
3. Facultative

Question 22

What bacteria is commonly implicated in endodontic root canal failures and persistent infections?

Answer 22

E. faecalis

Question 23

Two important groups of G+ rods

Answer 23

Actinomyces, Lactobacillus

Question 24

Actinomyces:

Answer 24

1. Forms major portion of plaque flora
2. Increases with gingivitis
3. Associated with root caries
4. Produces ECM
5. Sugar-substrate
6. Tolerates low pH

Question 25

Important species of Actinomyces

Answer 25

A. israelii

Question 26

Lactobacillus acidophilus:

Answer 26

1. increased numbers correlate well with a high-sugar, ‘cariogenic’ diet
2. dentin caries

Question 27

Which bacteria is associated with root caries?

Answer 27

Actinomyces

Question 28

2 common oral G- Cocci

Answer 28

Neisseria

Veillonella alcalescens

Question 29

Which G- Cocci can metabolize lactic acid?

Answer 29

Both Neisseria and Veillonella

Question 30

What G- rod bacteria is associated with aggressive periodontitis in juveniles (teenagers)?

Answer 30

Aggregatibacter actinomycetemcomitans

Question 31

Fusobacterium nucleatum:

Answer 31

Very long thin rod that many other bacteria attach to.

Associated with periodontitis

Question 32

Name common G- Rods that are associated with periodontitis:

Answer 32

1. Aggregatibacter actinomycetemcomitans
2. Fusobacterium nucleatum
3. Bacteroides
4. Tannerella
5. Porphyromonas
6. Prevotella

Question 33

Tannerella:

Answer 33

1. Associated with aggressive periodontal infections

2. Forms Red Complex with P. gingivalis and T. denticola

Question 34

What 3 bacteria make up red complex

Answer 34

Tannerella
P. gingivalis
T. denticola

Question 35

Important species of Tannerella

Answer 35

T. forsythensis

Question 36

Porphyromonas:

Answer 36

1. Asaccharolytic - protein-substrate (do not ferment carbohydrates - no acid produced)

Question 37

Important Porphyromonas species

Answer 37

P. gingivalis

Question 38

Prevotella:

Answer 38

Saccharolytic (can ferment carbs)

Question 39

Important Prevotella species

Answer 39

P. intermedia

Question 40

Spirochete group and species

Answer 40

Treponema

T. denticola (Asaccharolytic)