Lecture 1 - Oral Ecology and microbial diversity Flashcards Preview

Pedo Final > Lecture 1 - Oral Ecology and microbial diversity > Flashcards

Flashcards in Lecture 1 - Oral Ecology and microbial diversity Deck (62):
1

how do we detect bacterial species?

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

2

do we have more bacterial cells or human cells?

bacterial cells

3

Bray-Curtis beta diversity chart

defines that each body site harbors a distinct microbial community

4

ecology

study of interrelationships of organisms and their environment

5

niche

specific combination necessary for survival of an organism
parameters may be PHYSICAL, CHEMICAL and biological

6

the hard surfaces of teeth are unique because?

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

7

can microorganisms invade soft tissues?

yes. in periapical and odontogenic infections

8

what are some soft oral surfaces bacteria can adhere to?

sulcus
tongue
mucosa
gingiva

9

hard oral surfaces are either ___________ or _________

subgingival or supragingival

10

planktonic

floating in water

11

sessile

attached to a surface in biofilms

12

example of biofilms

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

13

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

adherent microorganisms
extracellular matrix
aqueous

14

the sticky material that holds biofilm together is

extracellular matrix

15

what are the 3 stages of biofilm life cycle?

attachment
growth
detachment

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

T
T
T

17

What turns on biofilm-adaptive genes?

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

18

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

biofilms

19

what are the 3 primary mechanism for biofilm antimicrobial resistance?

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

20

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

F
They need to attach or they'd be lost

21

biofilms can cause what 4 things?

caries
periodontitis
osteromyelitis
osteonecrosis secondary to bisphosphonate therapy

22

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

T

23

what are the 3 surface sites for adherence?

host surfaces (receptor molecules)
direct bacterial interactions
extracellular matrix

24

promotes by providing binding sites or inhibits by agglutinating and clearing

salivary binding

25

salivary binding is done by what 4 methods?

antibodies
salivary agglutinins
proline-rich glycoproteins
alpha amylase

26

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

toothbrush and floss

27

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

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

28

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

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

29

what requires oxygen at atmospheric levels for growth?

obligate aerobes

30

can switch between aerobic and anaerobic metabolism

facultative anaerobes or facultative aerobes

31

requiring low levels of oxygen

microaerophilic

32

anaerobic metabolism but tolerates the presence of oxygen

aerotolerant anaerobes

33

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

obligate anaerobes or aerophobes

34

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

superoxide dismutase
catalase
peroxidase

35

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

F
they can cause damage

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?

superoxide dismutase
catalase
peroxidase

37

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

T

F - lower Eh

38

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

F - anaerobic

39

which species are found in supragingival plaque?

facultative and microaerophilic

40

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

3% peroxide

41

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

F - indirect
Direct method example - drinking soft drink

42

pH normally ranges from __-____

5-7.5

43

low pH inhibits most species except:

acid tolerant (aciduric) strep and lactobacilli

44

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

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

45

saliva contains:
1
2
3
4
5

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

46

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

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

47

which secretory immunoglobulin in saliva prevents adhesion?

IgA

48

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

IgG

49

what is the main defense of innate immunity?

epithelial barrier and desqaumation

50

what are the major salivary proteins?

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

51

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

sialoperoxidase system

52

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

salivary lactoferrin and serum transferrin

53

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

salivary lysozyme

54

which salivary defense modulates salivary calcium and phosphate chemistry?

acidic proline rich proteins and statherin

55

which bacterium converts lactate to propionate?

veillonella

56

T/F veillonella lowers pH for acid-sensitive strep

F - raises pH

57

Which vitamin is synthesized by veillonella parvula?

vitamin K3

58

vitamin K3 is used by which two bacteria?

p. gingivalis
P. intermedia

59

Vitamin K3 synthesis and use is an example of what?

chain interdependency

60

Which strep bacterium produces enocin to inhibit s. pyogenes?

s. salivarius

61

organisms occupy niche, preventing establishment of new strains is:

colonization resistance

62

name 6 ecologic determinants

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