Lecture 1 - Oral Ecology and microbial diversity

Question 1

how do we detect bacterial species?

Answer 1

traditional methods include MICROSCOPY, CULTIVATION while new methods include 16S sequencing

Question 2

do we have more bacterial cells or human cells?

Answer 2

bacterial cells

Question 3

Bray-Curtis beta diversity chart

Answer 3

defines that each body site harbors a distinct microbial community

Question 4

ecology

Answer 4

study of interrelationships of organisms and their environment

Question 5

niche

Answer 5

specific combination necessary for survival of an organism

parameters may be PHYSICAL, CHEMICAL and biological

Question 6

the hard surfaces of teeth are unique because?

Answer 6

they are non-shedding. Microorganisms can form stable, thick biofilms (“dental plaque”)

Question 7

can microorganisms invade soft tissues?

Answer 7

yes. in periapical and odontogenic infections

Question 8

what are some soft oral surfaces bacteria can adhere to?

Answer 8

sulcus
tongue
mucosa
gingiva

Question 9

hard oral surfaces are either ___________ or _________

Answer 9

subgingival or supragingival

Question 10

planktonic

Answer 10

floating in water

Question 11

sessile

Answer 11

attached to a surface in biofilms

Question 12

example of biofilms

Answer 12

plaque on teeth
gunk in drains
rings in toilets
slippery coating on rocks in streams

Question 13

biofilms are made up of ______________ and ____________ in an ________ environment

Answer 13

adherent microorganisms
extracellular matrix
aqueous

Question 14

the sticky material that holds biofilm together is

Answer 14

extracellular matrix

Question 15

what are the 3 stages of biofilm life cycle?

Answer 15

attachment
growth
detachment

Question 16

T/F biofilm can be formed by single bacterial species
T/F biofilms often include many species of bacteria
T/F biofilms also include other micro-organisms like fungi, algae, protozoa

Answer 16

T
T
T

Question 17

What turns on biofilm-adaptive genes?

Answer 17

when bacteria detects surfaces
when bacteria detects each other (quorum sensing)
when signals pass between bacteria

Question 18

____________: stable, slow-growing communities that are highly resistant to antibiotics, host defenses and mechanical disruptions (antiseptics and disinfectants)

Answer 18

biofilms

Question 19

what are the 3 primary mechanism for biofilm antimicrobial resistance?

Answer 19

1. slowing of diffusion
2. “persister cells”: alive but metabolically inactive survive and repopulate biofilm
3. exchange of resistance genes

Question 20

T/F most bacteria in the mouth is free-floating

Answer 20

F

They need to attach or they’d be lost

Question 21

biofilms can cause what 4 things?

Answer 21

caries
periodontitis
osteromyelitis
osteonecrosis secondary to bisphosphonate therapy

Question 22

T/F to prevent oral biofilms we might need to prevent invasive diseases like cellulitis as well

Answer 22

T

Question 23

what are the 3 surface sites for adherence?

Answer 23

host surfaces (receptor molecules)
direct bacterial interactions
extracellular matrix

Question 24

promotes by providing binding sites or inhibits by agglutinating and clearing

Answer 24

salivary binding

Question 25

salivary binding is done by what 4 methods?

Answer 25

antibodies salivary agglutinins proline-rich glycoproteins alpha amylase

Question 26

what common measures are used to disrupt bacterial adherence in the mouth?

Answer 26

toothbrush and floss

Question 27

T/F the percentage of oxygen is greater in a closed mouth than in the air

Answer 27

F 12-14% oxygen in mouth. 21% in air

Question 28

Positive oxidation-reduction potential means LOW oxygen (T/F)

Answer 28

F + = aerobe = high oxygen - = anaerobe = low oxygen

Question 29

what requires oxygen at atmospheric levels for growth?

Answer 29

obligate aerobes

Question 30

can switch between aerobic and anaerobic metabolism

Answer 30

facultative anaerobes or facultative aerobes

Question 31

requiring low levels of oxygen

Answer 31

microaerophilic

Question 32

anaerobic metabolism but tolerates the presence of oxygen

Answer 32

aerotolerant anaerobes

Question 33

do not use oxygen as nutrient. Oxygen is toxic, killing or inhibiting growth

Answer 33

obligate anaerobes or aerophobes

Question 34

sensitivity of anaerobes to oxygen is due to the genetic inability to make enzymes like:__________, ____ and _________

Answer 34

superoxide dismutase catalase peroxidase

Question 35

T/F In the absence of enzymes like catalase and peroxidase, oxygen products with superoxide and peroxide cannot cause damage to cellular components

Answer 35

F | they can cause damage

Question 36

``` Which enzyme(s) detoxify oxygen radicals that are generated by living systems in presence of oxygen? The distribution of Which enzymes(s) determines their ability to exist in the presence of oxygen? ```

Answer 36

superoxide dismutase catalase peroxidase

Question 37

T/F Older plaque gets thick and becomes sheltered from oxygen Older plaque has higher oxidation-reduction potential and corresponding shift in microflora

Answer 37

T F - lower Eh

Question 38

T/F aerobic species are found primarily in oxygen-protected sites like the sulcus or mature coronal plaque

Answer 38

F - anaerobic

Question 39

which species are found in supragingival plaque?

Answer 39

facultative and microaerophilic

Question 40

what common therapy is designed to exploit oxygen sensitivity of oral bacteria?

Answer 40

3% peroxide

Question 41

T/F bacterial fermentation of sugars to lactate is an example of directly affecting pH

Answer 41

F - indirect | Direct method example - drinking soft drink

Question 42

pH normally ranges from __-____

Answer 42

5-7.5

Question 43

low pH inhibits most species except:

Answer 43

acid tolerant (aciduric) strep and lactobacilli

Question 44

what are the two major physical nutrient niches in oral cavity?

Answer 44

supragingival - saliva and ingested food | subgingival - crevicular food and cells

Question 45

``` saliva contains: 1 2 3 4 5 ```

Answer 45

``` 1 glycoproteins 2 inorganic salts 3 amino acids 4 glucose 5 vitamins ```

Question 46

T/F endogenous nutrients are not sufficient for plaque. | endogenous nutrients are not sufficient for caries.

Answer 46

F (they are sufficient) | T - they need exogenous carbs

Question 47

which secretory immunoglobulin in saliva prevents adhesion?

Answer 47

IgA

Question 48

which immunoglobulin in crevicular fluid is directed against periodontally important organisms both systemically and locally produced?

Answer 48

IgG

Question 49

what is the main defense of innate immunity?

Answer 49

epithelial barrier and desqaumation

Question 50

what are the major salivary proteins?

Answer 50

alpha-amylase: digests starches and binds bacteria | mucins: lubricants

Question 51

which salivary defense generates superoxide radicals which inactivate bacterial enzymes leading to bacterial death?

Answer 51

sialoperoxidase system

Question 52

which salivary defense binds iron so that it is not bioavailable to bacteria?

Answer 52

salivary lactoferrin and serum transferrin

Question 53

which salivary defense digest peptidoglycan in bacterial cell wall leading to osmotic disruption and cell death?

Answer 53

salivary lysozyme

Question 54

which salivary defense modulates salivary calcium and phosphate chemistry?

Answer 54

acidic proline rich proteins and statherin

Question 55

which bacterium converts lactate to propionate?

Answer 55

veillonella

Question 56

T/F veillonella lowers pH for acid-sensitive strep

Answer 56

F - raises pH

Question 57

Which vitamin is synthesized by veillonella parvula?

Answer 57

vitamin K3

Question 58

vitamin K3 is used by which two bacteria?

Answer 58

p. gingivalis | P. intermedia

Question 59

Vitamin K3 synthesis and use is an example of what?

Answer 59

chain interdependency

Question 60

Which strep bacterium produces enocin to inhibit s. pyogenes?

Answer 60

s. salivarius

Question 61

organisms occupy niche, preventing establishment of new strains is:

Answer 61

colonization resistance

Question 62

name 6 ecologic determinants

Answer 62

``` 1 surface receptors for adherence 2 oxygen tension (Eh) 3 pH 4 nutrients 5 host inhibitory factors 6 bacterial community interactions ```