Lecture 8 & 9 - Oral Ecology & Bacterial Plaque Biofilm

Question 1

Define biofilm

Answer 1

Matrix-enclosed bacterial populations adherent to each other and/or to surfaces or interfaces
- When maintained well by brushing, flossing and not eating a lot of sweets, they cause little problem

Question 2

T or F, microbes live as completely separate individual colonies

Answer 2

False, New thinking has shifted to understanding that they live as complex communities called biofilms

Question 3

6 Basic biofilm properties:

Answer 3

1. Complex cooperating and Competing community of different microorganisms
2. Microorganisms are arranged in microcolonies
3. Microcolonies are surrounded and attached together by protective matrix
4. Within, and between, the microcolonies are differing environments
5. Microorganisms have simple communication system
6. Microorganisms in biofilms are more resistant to antibiotics, antimicrobials, and host reponses

Question 4

T or F, Plaque can be compared to a field that is either a well-cared-for lawn or an uncontrolled weed patch.

Answer 4

True

Question 5

What changes may occur as plaque thickness increases?

Answer 5

1. Becomes less permeable to oxygen and saliva
2. Thicker plaque builds up higher concentrations of toxic products, acids, and inflammatory bacterial components. –This greatly changes the environment that encourages growth of different species.

Question 6

Supplemental flora are found:

Answer 6

in a minority of the population where they generally act like normal flora

Question 7

Transient flora consist of:

Answer 7

Microorganisms that are brought to the area from somewhere else.

Question 8

t or F, Transient flora are easily integrated into the area and help colonize and compete for nutrients

Answer 8

False, They almost always have a very difficult time colonizing and competing in the area, and are thus generally cleared within a few hours or days.

Question 9

What type of flora cause overt disease?

Answer 9

True pathogens, (However they will be cleared by subsequent immune response directed against them.)

Question 10

5 roles of normal flora:

Answer 10

1. Competition (innate defenses)
2. Vitamin K synthesis
3. Immune Stimuli: LPS –> Gut
4. Source of opportunists
5. Etiologic agents of caries and chronic inflamm. periodontal disease

Question 11

Normal flora is also known as:

Answer 11

Indigenous flora

Question 12

T or F, Normal flora are site specific, easy to clear but tend to recolonize

Answer 12

False, They are site specific, difficult to clear and tend to recolonize

Question 13

When does bacteria colonization begin?

Answer 13

At the moment of birth we begin to be colonized

Question 14

What vaginal microorganisms successfully colonize the oral cavity at birth?

Answer 14

Lactobacillus

Question 15

What bacteria is found on tongue mucosa?

Answer 15

Strep salivarious

Question 16

What bacteria is inhabits GI tract and fecal area

Answer 16

Bacteroides

Question 17

When teeth erupt, what bacteria colonizes in those new ecological sites?

Answer 17

Strep sanguinis

Question 18

What bacteria find a place where they can colonize and compete well with the appearance of the deep pits & fissures of 2nd molars

Answer 18

Strep. mutans

Question 19

T or F, S. salivarius can’t hold to saliva-pellicle

Answer 19

True

Question 20

As teeth emerge, within days what bacteria colonizes on hard enamel surface

Answer 20

S. sanguinis

Question 21

Where is the primary niche of S. salivarius

Answer 21

Tongue papilla and crypts

Question 22

Where do most bacteria in the mouth call home?

Answer 22

Tongue papilla and crypts

Question 23

Most of the early oral colonization of babies likely comes from where?

Answer 23

From their mother (typically their primary care-giver)

Question 24

The more S. mutans the mother has in her mouth means what for the child?

Answer 24

The faster the child will become colonized

Question 25

t or F, S. sanguinis do not appear in significant numbers in the mouth until after the teeth erupt

Answer 25

True

Question 26

When do S. mutans begin to effectively colonize in the oral cavity?

Answer 26

Typically first appear in large numbers when the pits & fissures of the 2nd molar emerge at about 19 months

Question 27

T or F, Oral bacterial species are evenly distributed within the mouth and biofilm

Answer 27

False, They are not evenly distributed, but rather find their own ecological niche. Some appear to be dependent on the enamel surface for colonization (mutans) while some are not (salivarius)

Question 28

supragingival plaque contains what bacteria

Answer 28

mostly gram positive bacteria such as Streptococcus and Actinomyces

Question 29

Subgingival plaque contains what bacteria

Answer 29

Significant numbers of G- bacteria such as Treponema and Fusobacterium with few G+ bacteria

Question 30

T or f, The bacteria often form multicellular, multispecies complexes held together by linking polymers = biofilms

Answer 30

True

Question 31

Dr. Harold Loe developed a model to study the effects of poor oral hygiene, what did he find?

Answer 31

As time went on the percentage of gram-negative anaerobic bacteria increased, while the number of aerobic bacteria decreased. At the same time the gram-negatives were increasing so was gingivitis. Once oral hygiene resumed the numbers reverted back to normal and the gingivitis reversed.

Question 32

T or F, As plaque increases in complexity and density, a food chain develops, where some bacterial end products provide the substrate or conditions beneficial for other bacteria

Answer 32

True

Question 33

What type of bacteria would be considered primary feeders?

Answer 33

Strep. species because they can metabolize the food we eat (sugars)
- Other bacteria can utilize the secreted end-products of the ‘primary’ feeders.

Question 34

What is the primary food source in subgingival plaque? What is the composition of these bacteria?

Answer 34

Plasma proteins in gingival fluid

- Primary feeders subgingivally are various asaccharolytic, gram negative rods

Question 35

Menadione is a Vitamin K Precursor

Answer 35

True

Question 36

What is the primary food source in subgingival plaque?

Answer 36

Plasma proteins in the gingival fluid

Question 37

What are the “primary feeders” subgingivally

Answer 37

various asaccharolytic, G- rods

Question 38

Name two bacteria that are subgingival bugs taht use menadione as food

Answer 38

P. intermedius

P. gingivalis