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Pedo > Lecture 1: Oral ecology > Flashcards

Lecture 1: Oral ecology Flashcards

1
Q

method for bacterial detection

A

16S sequencing, rDNA gene alignment

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2
Q

how much of the oral cavity bacteria has been cultivated

A

more than half

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3
Q

how many species of oral bacteria exist?

A

700 species

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4
Q

how many species of oral bacteria do individuals carry?

A

100-200 species

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5
Q

what is the study of interrelationships of organisms and their environment?

A

ecology

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6
Q

What is a niche?

A

specific combination of conditions that are necessary for the survival of particular organisms (chemical, physical, biological)

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7
Q

where do microorganisms form stable, thick biofilms (plaque)?

A

non-shedding hard surfaces of teeth

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8
Q

how are periapical and odontogenic infections formed?

A

invasion of micro-organisms into soft tissue

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9
Q

soft-tissue surfaces to which bacteria adheres:

A

sulcus, tongue, mucosa, gingiva

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10
Q

hard tissue (supra) to which bacteria adheres:

A

fissures, proximal surfaces, buccal and lingual enamel surfaces, cementum, restorations, calculus

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11
Q

hard tissue (sub) to which bacteria adheres:

A

enamel, cementum, restorations, calculus

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12
Q

____ bacteria floats in water

A

planktonic

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13
Q

Bacteria that causes most dental problems and medical problems are _____, attach to the surface in biofilms

A

sessile

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14
Q

biofilms are made up of ____and ____ in an ____

A

adherent microorganisms, extracellular matrix, aqueous enviornment

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15
Q

3 steps of biofilm life cycle

A

1) attachment 2) growth 3) detachement to seed new biofilm

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16
Q

T/F: biofilms can be formed from one species of bacteria

A

true

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17
Q

T/F: biofilms normal have many species of bacteria

A

true

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18
Q

biofilms can include other microorganisms such as:

A

fungi, algae, protozoa

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19
Q

Once bacteria attach to a surface, they ____

A

change

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20
Q

biofilm-adaptive genes turn on when:

A
  • bacteria detect surfaces
  • bacteria detect each other (quorum)
  • signals pass between bacteria
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21
Q

biofilm species co-exist and cooperate through:

A
  • provide nutrients
  • remove toxins
  • inter and intra cellular signalling
  • division of labor (metabolism)
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22
Q

T/F biofilms are fast growing communities that are highly resistant to antibiotics, host defenses, and mechanical disruption

A

false, slow growing

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23
Q

antibiotic dose to kill biofilm bacteria

A

1000x

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24
Q

3 mechanisms for biofilm antimicrobial resistance:

A

1) slow diffusion
2) persister cells alive but metabolicaly inactive survive and repopulate biofilm
3) close proximity and exchange of resistance genes

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25
Q

T/F most oral bacteria is planktonic

A

false

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26
Q

Saliva is the main precursor for biofilms

A

false

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27
Q

Biofilms cause oral problems such as:

A
  • caries
  • periodontitis
  • osteomyelitis
  • osteonecrosis secondary to bisphosphonate therapy
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28
Q

T/F: preventing oral biofilms prevents some invasive diseases such as cellulitis

A

true

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29
Q

6 oral ecologic determinants for biofilm growth

A
  1. surface receptors for adherence
  2. oxygen tension (Eh)
  3. pH
  4. nutrients
  5. host inhibitory factors
  6. bacterial community interactions
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30
Q

what are surface sites to which bacteria adheres?

A
  • receptor molecules
  • direct bacterial interactions
  • extracellular matrix
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31
Q

salivary binding promotes adherence by providing ____ or inhibits by ____ and _____

A

providing binding sites, agglutinating, clearing

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32
Q

components of saliva

A
  • antibodies (aquired immunity)
  • salivary agglutinins
  • proline- rich glycoproteins
  • alpha-amylase
33
Q

What is the electrical potential or tendency to oxidize or reduce?

A

oxidation-reduction potential (Eh)

34
Q

Eh of aerobes?

A

positive

35
Q

Eh of anaerobes?

A

negative

36
Q

_____ require O2 at atmospheric levels for growth

A

obligate aerobes

37
Q

____ can switch between aerobic and anearobic metabolism

A

facultative anaerobes (facultative aerobes)

38
Q

____ require low levels of O2

A

microaerophilic

39
Q

T/F aerotolerant anaerobes possess anaerobic metabolism but tolerate the presence of O2

A

true

40
Q

to which class of microorganism is O2 toxic?

A

obligate anaerobes (aerophobes)

41
Q

how is oxygen toxic to obligate anaerobes?

A
  • causes oxidation of membrane lipids and destruction of cell integrity
  • causes oxidation of sulfhydryl groups in enzymes resulting in cross-linking and inactivity
42
Q

which groups in enzymes are effected by oxygen leading to inactivity?

A

sulfhydryl groups

43
Q

what 3 enzymes are anaerobes unable to make?

A

1) superoxide dismutase (SOD)
2) catalase
3) perroxidase

44
Q

which oxygen products cause damage to cells?

A

superoxide and peroxide

45
Q

superoxide dismutase, catalase, and peroxidase ____ oxygen radicals

A

detoxify

46
Q

T/F the number of detoxifying enzymes in the cell determines the ability for them to exist in O2 enviroment

A

false, distribution

47
Q

older plaque has a ___ Eh

A

lower

48
Q

anaerobic species are found in?

A

sulcus or mature coronal plaque

49
Q

facultative and microaerophilic specis found in?

A

supragingival plaque

50
Q

what species scavanges O2 to provide anaerobic environment for other species (bridge)?

A

fusobacterium (F. nucleatum)

51
Q

pH of soft drink

A

3

52
Q

pH of fermentation product; lactate

A

5

53
Q

pH in mouth ranges from ____ to _____

A

5 to 7.5 (periodontal pocket)

54
Q

what are the nutrients of the supragingival environment?

A

saliva and ingested food

55
Q

what are the nutrients of the subgingival environment?

A

crevicular fluid and cells

56
Q

T/F carbs and aa’s are readily taken up by bacteria

A

true, low MW

57
Q

T/F protens and starches (sticky) are readily taken up by bacteria

A

false, must be retained

58
Q

nutrients of saliva?

A

glycoproteins, inorganic salts, aa’s, glucose, vitamins

59
Q

components of gingival crevicular fluid?

A

serum proteins, aa’s, glucose, vitamins, hemin, hormones

60
Q

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

A

true, exogenous carbs are needed

61
Q

what antibody prevents adhesion?

A

IgA

62
Q

IgG acts by?

A
  • inhibits colonization (block binding site/agglutingation)
  • act as opsonin
  • activate complement system
63
Q

T/F neutrophils, complement proteins of crevicular fluid, and antimicrobial peptids (defensins, histatins, cathelicidins) are considered innate immune defenses?

A

true

64
Q

T/F saliva is an innate defense

A

true

65
Q

the major salivary protein that digests starches and binds bacteria and mucins is ______

A

alpha-amylase

66
Q

salivary _____ digests peptidoglycan in cell wall leading to osmotic disruption and cell death

A

lysozyme

67
Q

salivary ____ and ____ sequesters iron

A

lactoferrin and serum transferrin

68
Q

what system produces superoxide radicals to inactivate bacterial enzymes?

A

sialoperoxidase system

69
Q

T/F antimicrobial peptides have activity against bacteria and yeast

A

true

70
Q

____ and ____ modulate salivary calcium and phosphate chemistry

A

acidic proline-rich proteins and statherin

71
Q

lactate produced by streps is required by _____

A

veillonella

72
Q

veillonella vonverts lactate to _____ to raise pH for acid-sensitive ____

A

propionate strep

73
Q

vitamin K3 (menadione) is synthesized by _____ and used by _____ and _____

A

veillonella parvula, P. gingivalis, P. intermedia

74
Q

carbon dioxide is generated by _____ and _____

A

peptostreptococci and eubacteria

75
Q

carbon dioxide enhances growth of ____ and ____

A

capnocytophaga and actinomycetemcomitans

76
Q

_____ removes oxygen to help species like _____ survive

A

F. nucleatum/periodonticum, taneralla forsythia

77
Q

T/F strep salivarius produces enocin (bacteriocin) that inhibits S. pyrogenes

A

true

78
Q

major oral niches/ecosystems

A
  • supragingival tooth surface and dorsum of tongue

- gingival crevice

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