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AU 15- Oral Micro > Oral Ecology and Microbial Diversity > Flashcards

Oral Ecology and Microbial Diversity Flashcards

1
Q

What two methods are used to detect bacterial species?

A

Microscopy and Cultivation

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2
Q

Which method of bacterial detection is better for distinguishing between similar morphotypes?

A

Cultivation

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3
Q

Detection of bacterial species by cultivation requires specific _______.

A

Nutrients

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4
Q

During bacterial cultivation, _______ species and _______ species are overgrown.

A

Minor and Slow-growing

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5
Q

True or False: In the oral cavity, 1/4 of all species have been cultivated.

A

False: More than half of the species have been cultivated.

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6
Q

What is 16S sequencing?

A

well-established sequencing method used to identify and compare bacteria present within a given sample; good for studying phylogeny and taxonomy

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7
Q

Through 16S sequencing, it was determined that there are around _____ species common within the oral cavity.

A

700

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8
Q

How many species of bacteria are present in one individual?

A

100-200

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9
Q

Because the mouth is an open system, there are _____ and _______.

A

Transient Species and True Residents

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10
Q

What is the name of the study that aimed to determine whether individuals share a core microbiome and whether changes in biome correlate to health?

A

Human Microbiome Project

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11
Q

True or False: Each person has more bacterial cells than human cells.

A

True

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12
Q

Individuals differ among each other, although ______ are shared at distinct body sites.

A

some core species

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13
Q

What was the importance of the “Early Contact” study?

A

The study sought to disprove the hygiene hypothesis (don’t kiss your baby to avoid transmission of s.mutans). By studying near-preterm babies that were either home-reared or kept in NICU, the study showed that the array of bacteria present at 3 months was identical.

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14
Q

______ is the study of the interrelationships of organisms and their environment.

A

Ecology

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15
Q

A ______ is the specific combination of conditions (physical , chemical, or biological) that are necessary for the survival of a particular organism.

A

Niche

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16
Q

Thick, stable biofilms on hard surfaces of teeth is also known as _______.

A

Dental plaque

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17
Q

Periapical and Odontogenic infections occur after invasion of _______ by micro-organisms.

A

Soft Tissues

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18
Q

When discussing different niches in the oral cavity, what are the two broad categories?

A
  1. Non-shedding (unique) HARD SURFACES

2. Soft Tissue

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19
Q

How does the oral ecology change over time?

A
  1. Acquisition of new organisms from outside the body

2. Changing of oral structures (eruption/loss, pocket formation, injuries)

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20
Q

Biofilm thickness _______ over time.

A

Increases

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21
Q

What are the soft tissue surfaces to which bacteria adhere?

A

Sulcus, Tongue, Mucosa, Gingiva

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22
Q

What are the categories of hard surfaces to which bacteria adhere?

A
  1. Supra-Gingival Surfaces

2. Subgingival Surfaces

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23
Q

What are the most common locations of dental plaque on supra-gingival hard surfaces?

A
  1. Fissures 2. Proximal Surfaces
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24
Q

Bacteria are classified as either _______ or ______.

A

Planktonic or Sessile

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25
Q

Which type of bacteria is 1000 times easier to clear than the other?

A

Planktonic is easier than Biofilms (sessile)

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26
Q

_______ bacteria are floating in water.

A

Planktonic

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27
Q

Most bacteria that cause dental problems are _______.

A

Sessile

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28
Q

Which type of bacteria attach to the surface of biofilms?

A

Sessile

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29
Q

Biofilms are made up of _______ and ________ in an aqueous environment.

A

adherent microorganisms and extracellular matrix

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30
Q

What is the glue-like substance that holds the biofilm together and anchors bacteria?

A

Extracellular Matrix

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31
Q

True or False: Water flows through the extracellular matrix via channels.

A

True

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32
Q

Within a biofilm, bacteria are able to detect one another and communicate via ______ ________.

A

Quorum Sensing

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33
Q

What are the three stages of a biofilm life cycle?

A
  1. Attachment
  2. Growth
  3. Detachment
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34
Q

True or False: Biofilms can be formed by a single bacterial species or many species, but cannot include other micro-organisms such as fungi, algae or protozoa.

A

False: They CAN include other micro-organisms, single, or multiple species.

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35
Q

Once bacteria attach to a surface, they ______.

A

Change (turn on a different set of genes)

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36
Q

Why is biofilm bacterial behavior more complex than suspended cell behavior?

A

Biofilm bacteria live in interactive communities

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37
Q

What are the three situations in which biofilm-adaptive genes are turned on?

A
  1. Bacteria detect surfaces
  2. Bacteria detect each other
  3. Signals pass between bacteria
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38
Q

What are four benefits to multiple species co-existing within a biofilm?

A
  1. Provide nutrients for each other
  2. Remove toxins
  3. Inter/Intra-Species signaling
  4. Division of labor within and among species
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39
Q

Biofilms are stable, slow-growing communities that are highly resistant to _______, ________, and ________.

A

Antibiotics
Host Defenses
Mechanical Disruption

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40
Q

______ doses that kill suspended cells must be increased by 1000-fold to kill biofilm cells (which would be toxic to the host).

A

Antibiotic

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41
Q

What are the three primary mechanisms for biofilm antimicrobial resistance?

A
  1. Slowing of diffusion
  2. Inactive “Persister Cells” repopulate the biofilm
  3. Exchange of resistance genes via close proximity
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42
Q

Most bacteria in the mouth are NOT _______.

A

Planktonic (free-floating)

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43
Q

True or False: Saliva is a thick film on oral structures.

A

False. Saliva is just a thin film (a few microns)

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44
Q

Biofilms are the cause of many oral problems such as caries, osteomyelitis, _______ and ________.

A

Periodontitis

Osteonecrosis

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45
Q

Some oral diseases, such as cellulitis, are caused by ______ bacteria, not biofilm bacteria.

A

invasive

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46
Q

What are the six factors that contribute to the oral cavity environment and create specific niches?

A
  1. Bacterial Adherence
  2. Oxygen Tension
  3. pH
  4. Bacterial food supply or substrate
  5. Host inhibitory factors
  6. Bacterial community interactions
47
Q

Bacteria are able to adhere to host surfaces, other bacteria, and/or ________.

A

Extracellular Matrix

48
Q

Saliva will promote binding by providing _________ or inhibit binding by _________.

A

Promotion: Binding Sites
Inhibition: Agglutinating/Clearing

49
Q

Bacteria are able to bind to the host pellicle by binding to components of saliva. What are the four discussed components that bind bacteria?

A
  1. Antibodies
  2. Salivary Agglutinins
  3. Proline-Rich Glycoproteins
  4. alpha-amylase
50
Q

What is the main component of saliva (and oral soft tissues) that will bind bacteria?

A

Alpha-amylase

51
Q

Oxygen tension is the _______ of oxygen compared to other gases.

A

partial pressure

52
Q

Compare the percent oxygen (oxygen tension) that is present in a periodontal pocket to the closed mouth and to the air.

A

Perio pocket = 1-2%
closed mouth = 12-14%
Air = 21%

53
Q

What is the oxygen tension within supragingival plaque? What accounts for the somewhat large range?

A

1-20%

the age of the plaque has a large influence on percent

54
Q

_________ is the electrical potential or tendency to oxidize/reduce (oxygen level)

A

Oxidation-Reduction Potential (Eh)

55
Q

A positive Eh aerobe will have ______ oxygen. A negative Eh anaerobe will have _______ oxygen.

A

+ high

- low

56
Q

_______ require oxygen at atmospheric levels in order to grow.

A

Obligate Aerobes

57
Q

______ can switch between aerobic and anaerobic metabolism.

A

Facultative Anaerobes (or faculatative aerobes)

58
Q

Which kind of microorganism requires low levels of oxygen?

A

microaerophilic

59
Q

Which type of microorganism thrives without oxygen but will tolerate its presence?

A

Aerotolerant anaerobe

60
Q

______ do not use oxygen as a nutrient and are killed or inhibits by it.

A

Obligate anaerobes

61
Q

Which type of microorganism will not be found in the oral environment? What is the oxygen tension in a closed mouth?

A

Obligate anaerobes

12-14% oxygen

62
Q

_________ causes oxidation of membrane lipids which leads to destruction of cell integrity, and oxidation of enzyme sulfhydryl groups resulting in cross-linking (inactivity).

A

Oxygen Toxicity

63
Q

The genetic inability to make ________ is the cause of anaerobic sensitivity to oxygen.

A

Enzymes:
SOD (superoxide dismutase)
catalase
peroxidases

64
Q

What happens when aerobes face oxygen without the appropriate enzymes present?

A

oxygen products (superoxide and peroxide) cause damage to cellular constituents

65
Q

What three important enzymes are responsible for detoxifying oxygen radicals that are generated by living systems in the presence of oxygen?

A

Superoxide Dismutase
Catalase
Peroxidase

66
Q

Why does older plaque have a lower Eh?

A

Eh (oxidation-reduction potential)

older plaque gets thick and becomes sheltered from oxygen. This causes a change in the microflora

67
Q

What species are typically found in the sulcus or mature coronal plaque?

A

Anaerobic (these sites are protected from oxygen)

68
Q

What species are found in supragingival plaques?

A

facultative and microaerophilic

69
Q

_________ species scavenge oxygen and help to provide an anaerobic environment for other species.

A

Fusobacterium

70
Q

Ingested foods indirectly affect pH through bacterial fermentation of sugar to _______.

A

Lactate

pH= 5

71
Q

The inflammation within periodontal pockets creates an environment with a pH around _____.

A

7.5

72
Q

____ pH inhibits most oral species except strep and lactobacilli.

A

low

strep and lactobacilli are “acid tolerant”

73
Q

Supragingival pH is _______ than subgingival pH.

A

lower

74
Q

Supragingival oxygen is _______ than subgingival.

A

higher

75
Q

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

A
  1. Subgingival

2. Supragingival

76
Q

The supragingival environment includes endogenous _______ and exogenous _______.

A

saliva

ingested foods

77
Q

The subgingival environment includes _______ fluid and cells.

A

crevicular

78
Q

True or False: The subgingival environment contains exogenous components.

A

False: only endogenous, ingested nutrients do NOT reach subgingivally

79
Q

Based on bioavailability, the nutrients sources in the oral cavity are either _______ or _________.

A
  1. Low molecular weight, soluble carbs and amino acids

2. Starches and proteins

80
Q

What type of ingested nutrient is readily taken up by bacteria?

A

low molecular weight, soluble carbs or amino acids

81
Q

What type of ingested nutrient must be retained in order for bacterial digestion to occur?

A

starches and proteins

82
Q

Saliva contains glycoproteins, inorganic salts, amino acids, glucose, and vitamins which is only available to ______ inhabitants.

A

SUPRAgingival

83
Q

What are the four discussed endogenous nutrient sources?

A
  1. saliva
  2. shed host cells
  3. gingival crevicular fluid
  4. breakdown products of periodontal tissue
84
Q

_________ contains tissue and serum proteins, amino acids, glucose, vitamins, hemin, and hormones.

A

Gingival crevicular fluid

85
Q

The _____ and ______ of gingival crevicular fluid is influenced by degree of inflammation.

A

flow and composition

86
Q

Tube-fed patients have an abundance of both supra and subgingival plaque because ______ nutrients are sufficient.

A

endogenous

87
Q

Why are endogenous nutrients not sufficient for caries formation?

A

Because exogenous carbohydrates are required

88
Q

Host inhibitory factors include ______immunity, ______immunity, and ______.

A

Innate
Specific
Saliva

89
Q

What are three important mechanisms of host antibodies?

A
  1. Inhibit colonization
  2. act as opsonins
  3. activate complement system
90
Q

Which immunoglobulin in saliva is important for preventing adhesion?

A

salivary Ig A

91
Q

Which immunoglobulin acts in crevicular fluid to directly combat periodontal organisms?

A

Ig G

92
Q

________ are a component of innate immunity and account for 95% of leukocytes in crevicular fluid.

A

neutrophils

93
Q

True or False: Neutrophils are abundantly present throughout the mouth.

A

False: neutrophils are not active supragingivally

94
Q

Antimicrobial peptides are produced in the _______ and participate in innate immunity.

A

salivary glands

95
Q

What are the two MAJOR salivary proteins?

A

alpha-amylase

mucins

96
Q

Which salivary protein is important for digestion of starch and binding of bacteria?

A

alpha amylase

97
Q

Which salivary protein acts as a lubricant?

A

mucin

98
Q

What are the seven minor salivary proteins?

A
  1. Lysozyme
  2. lactoferrin
  3. serum transferrin
  4. sialoperoxidase
  5. antimicrobial peptides
  6. acidic proline-rich
  7. statherin

“Some Silly Ladies Act Stupid And Lazy”

99
Q

Salivary ______ digests peptidoglycan in the bacterial cell wall, leading to osmotic disruption and cell death.

A

lysozyme

100
Q

Which two minor salivary proteins are responsible for binding iron so that it is not available to bacteria?

A

lactoferrin and serum transferrin

101
Q

_______ generates superoxide radicals which inactivate bacterial enzymes and lead to bacterial death.

A

sialoperoxidase

102
Q

Which salivary component acts against bacteria and yeast to create porins?

A

antimicrobial peptides

103
Q

Which two salivary components protect the mineral integrity of oral structures by modulating calcium and phosphate chemistry?

A

acidic proline-rich proteins and statherin

“To maintain Calcium and Phosphate you must….follow the STAT- IC PRO”

104
Q

What are the two mechanisms for maintaining the integrity of teeth?

A
  1. pellicle proteins/salivary minerals

2. salivary buffering

105
Q

What are the two discussed bacterial products that are used by other bacteria as nutrients?

A 
Lactic Acid (metabolized sugar)
Vitamin K3 (menadione)
106
Q

Veillonella is a critical component of the bacterial food chain. Veillonella soaks up lactate byproducts and converts it to ________ which in turn raises the pH for acid-sensitive strep.

A

propionate

107
Q

Which bacterial product is used by P. gingivalis (perio disease) after it is synthesized by Veillonella?

A

menadione (vitamin K3)

108
Q

_____ and _____ are bacterial products whose presence or absence will alter the environment and allow specific bacteria to thrive.

A

Carbon dioxide

oxygen

109
Q

_______ are bacterial inhibitory factors that are produced by one bacteria and inhibit another.

A

bacteriocins

110
Q

What is colonization resistance?

A

established organisms occupy a certain niche and prevent establishment of new strains

111
Q

Is pH greater for subgingival or supragingival environments?

A

subgingival

112
Q

Which niche is able to utilize ingested nutrients?

A

supragingival bacteria

113
Q

What are the two major oral niches (ecosystems)?

A
  1. Supragingival tooth surface and dorsum of tongue

2. gingival crevice (subgingival tooth and crevicular epithelial surfaces

AU 15- Oral Micro (11 decks)

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