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Oral Microbiology > Lecture 1 - Ecology & Microbial Diversity > Flashcards

Lecture 1 - Ecology & Microbial Diversity Flashcards

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1
Q

What are the traditional methods by which we detect bacterial species?

A
  • Microscopy
  • Cultivation
  • DNA methods
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2
Q

In the oral cavity, more than ____ of species have been cultivated.

A

half

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3
Q

Each person harbors around ___ species? (how many)

A

200

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4
Q

Within our bodies, we have slightly ____ bacterial cells than human cells. (more or less)?

A

more

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5
Q

Our microbiota includes much more ___ variety than our human genome.

A

DNA

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6
Q

The study of the interrelationships of organisms and their environment.

A

Ecology

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7
Q

The specific combination of conditions that are necessary for the survival of a particular organism. Parameters may be physical, chemical, or biological.

A

Niche

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8
Q

T/F

There are multiple niches within the oral cavity because different oral sites harvest different bacterial species.

A

True

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9
Q

Examples of soft tissue surfaces in the oral cavity to which bacteria adhere are:

A
  • sulcus
  • tongue
  • mucosa
  • gingiva
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10
Q

Hard surfaces develop a visible biofilm called:

A

dental plaque

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11
Q

Some bacteria are ________, meaning they are free-floating in water.

A

planktonic

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12
Q

Most of the bacteria that cause dental problems and many medical problems are _______ and are attached to a surface in biofilms.

A

sessile

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13
Q

Biofilms are made up of what 2 things within an aqueous environment?

A
  • adherent microorganisms

- extracellular matrix

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14
Q

Bacteria excrete a slimy, glue-like substance that helps adhere them to surfaces. It also hold the biofilm together. What is the substance?

A

Extracellular matrix

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15
Q

Describe the biofilm lifecycle.

A
  • attachment
  • growth to mature biofilm community
  • detachment of cells to seed new biofilm formation
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16
Q

T/F

Biofilm can be formed by a single bacterial species.

A

True

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17
Q

T/F
More often, biofilms include many species of bacteria, but do not include other microorganisms such as fungi, algae, or protozoa.

A

False

Biofilms may also include fungi, algae, or protozoa.

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18
Q

T/F
Biofilms are stable, slow-growing communities that are highly resistant to antibiotics, host defenses, and mechanical disruption.

A

True

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19
Q

Antibiotic doses that kill planktonic cells need to be increased as much as ____-fold to kill biofilm cells (impractical/toxic)

A

1,000

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20
Q

Primary mechanisms for biofilm antimicrobial resistance include:

A
  • slowing of diffusion
  • “persister cells” (alive, but metabolically inactive)
  • close proximity and exchange of resistance genes
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21
Q

What are the 6 ecological determinants that contribute to the environment in the oral cavity and create specific niches?

A
  • Bacterial adherence
  • Oxygen tension (Eh)
  • pH
  • Bacterial food supply or substrate (nutrients)
  • Host inhibitory factors
  • Bacterial community interactions
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22
Q

Host surfaces, direct bacterial interactions, and extracellular matrix provide surface sites for _________.

A

adherence

23
Q

This can either promote (provides binding sites) or inhibit (agglutinating and clearing) in regard to bacterial adherence.

A

Salivary binding

24
Q

The percentage of oxygen in the air is about __%, whereas in the closed mouth it’s about __-__%.

A

21%

12-14%

25
Q

This is the electrical potential or the tendency to oxidize or reduce (oxygen level).

A

Oxidation-Reduction Potential (Eh)

26
Q

This type of microorganism requires O2 at atmospheric levels for growth.

A

obligate aerobe

27
Q

This type of microorganism can switch between aerobic and anaerobic metabolism

A

facultative bacteria

28
Q

This type of microorganism does not use O2; in fact, O2 is toxic and can kill the microorganism or inhibit growth.

A

anaerobe

29
Q

Oxygen toxicity causes oxidation of what two things?

A
  • membrane lipids (destruction of cell integrity)

- sulfhydryl groups in enzymes (cross-linking and inactivity)

30
Q

The sensitivity of anaerobes is due to the genetic inability to make enzymes such as (which 3 enzymes)?

A
  • superoxide dismutase
  • catalase
  • peroxidases
31
Q

What is the action of superoxide dismutase, catalase, and peroxidase?

A

They detoxify oxygen radicals that are generated by living systems in the presence of O2.

32
Q

What types of species might you find in supragingival plaques?

A
  • facultative

- microaerophilic

33
Q

This species scavenges O2 and helps to provide an anaerobic environment for other species.

A

Fusobacterium

34
Q

Normal oral pH is …?

A

7.0

35
Q

Low pH inhibits most oral species except acid tolerant species such as…?

A
  • Strep

- Lactobacilli

36
Q

According to Griffen’s lecture, what three factors are needed for development of caries?

A
  • bacteria
  • substrate
  • vulnerable tooth
37
Q

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

A
  • supragingival environment (saliva and ingested food)

- subgingival environment (crevicular fluid and cells)

38
Q

Ingested food is an example of an _________ nutrient source for microbes.

A

exogenous

39
Q

Endogenous nutrient sources for microbes include:

A
  • saliva
  • shed host cells
  • gingival crevicular fluid
  • breakdown products from periodontal tissues
40
Q

T/F

Endogenous nutrients are sufficient for plaque, but exogenous nutrients (i.e. carbs) are needed for caries.

A

True

41
Q

Host inhibitory factors include:

A
  • specific immunity
  • innate immunity
  • saliva
42
Q

Which antibody is present in saliva and prevents adhesion?

A

sIgA (secretory immunoglobin A)

43
Q

Which antibody is present in crevicular fluid and is directed against periodontically important organisms?

A

IgG

44
Q

The two major salivary proteins are:

A
  • alpha-amylase

- mucins

45
Q

Salivary defenses (minor proteins) include:

A
  • salivary lysozyme
  • salivary lactoferrin and serum transferrin
  • Sialoperoxidase system
  • antimicrobial peptides
  • acidic proline-rich proteins and statherin
46
Q

What is the function of salivary lysozyme?

A

Digests peptidoglycan in bacterial cell wall leading to osmotic disruption and cell death

47
Q

What is the function of salivary lactoferrin and serum transferrin?

A

They bind iron so that it is not bioavailable to bacteria

48
Q

What is the function of the sialoperoxidase system?

A

Generates superoxide radicals which inactivate bacterial enzymes leading to bacterial death

49
Q

What do antimicrobial peptides in saliva do?

A

They have activity against bacteria and yeast

50
Q

What do acidic proline-rich proteins and statherin do?

A

They modulate salivary calcium and phosphate chemistry

51
Q

What are two mechanisms for maintaining tooth integrity?

A
  • pellicle proteins/salivary minerals

- salivary buffering

52
Q

Which two bacterial products act as nutrients?

A
  • lactic acid (streptococci and veillonella)

- vitamin K3 (made by veillonella and used by P. gingivalis and P. intermedia)

53
Q

What two bacterial products/processes alter the environment?

A
  • carbon dioxide

- removal of oxygen

54
Q

What are two microbial inhibitory factors?

A
  • bacteriocins

- colonization resistance

Oral Microbiology (10 decks)

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