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Pedo Exam > Oral Ecology and Microbial Diversity > Flashcards

Oral Ecology and Microbial Diversity Flashcards

1
Q

What are the two traditional methods of studying bacteria and what are the problems?

A

Microscopy: hard to distinguish between bacteria of similar morphotypes

Cultivation: need nutrients; may have a bacteria that inhibits the growth of another bacteria

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2
Q

What is the new way to study bacteria and what does it entail?

A

16s sequencing:
form phylogenetic trees
form rDNA gene alignments

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3
Q

Around how many oral bacteria species have been found?

How many does each individual carry in their own mouth?

A

We have discovered about half of the bacteria in the mouth; around 700 species

Each individual caries around 100-200 species in their own mouth

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4
Q

What are the two general types of bacteria in the mouth?

A

Transient: only there sometimes

True Resident: always in the mouth

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5
Q

What is a microbiome?

How are microbiomes related at different body sites?

A

totality of microbes in a single area
The oral microbiome is very unique, whereas skin and nasal have more overlap
There is a distinct microbiome for each body site

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6
Q

What was the study done and what was the result of the study NICU vs Home Reared Babies?

A

Some babies were put in an incubator after birth and monitored and some babies were taken home

They were tested after 1 day, 2 weeks and 3 mos

The end result was that there was no significant difference in microbiota between the two different groups

Conclusion: bacterial growth is depends on the host control

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7
Q

What is Ecology?

A

The study of interrelationships between an organism and its environment

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8
Q

What is a niche?

A

The several conditions that must be present for an organism’s survival

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9
Q

How many niches are in the oral cavity?

What are the two main niches and what happens when bacteria forms there? Where do bacteria get their nutrients in each niche?

A

Multiple Niches

Non shedding hard surfaces:

  • bacteria can form stable thick biofilm
  • wet environment that provide nutrients to the bacteria
  • bacteria gets food when food passes over teeth

Soft tissues

  • bacteria invade tissues and cause periapical and odontogenic infections
  • bacteria get nutrients from crevicular fluid

YOU CAN NEVER REMOVE ALL OF THE BIOFILM FROM A TOOTH (constant battle)

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10
Q

What surface of the tooth do people get most tooth decay?

A

Pits and Fissures

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11
Q

What symptom is most common when biofilm forms on the tongue and how is it protected?

A

The tongue has crypts and groves that allow bacteria to “hang out” and “hide” in. Over time can cause HALITOSIS–>mal odor

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12
Q

No surface in the mouth is…

A

STERILE

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13
Q

What is formed by bacteria and increases thickness over time?

A

Biofilm

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14
Q

Where do biofilms form in soft tissue surfaces?

In hard tissue surfaces?

A 
Soft tissue:
-tongue
-sulcus
-gingiva
-mucosa
Hard tissues:
(supragingival)
-pits/fissures
-proximals
-direct buccal/lingual
-cementum
-restorations
-calculus
Hard tissues:
(subgingival)
-cementum
-restorations
-calculus
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15
Q

What is considered a biofilm, calculus trap on the tooth?

A

THE CEJ

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16
Q

What is planktonic bacteria?

A

Planktonic bacteria is bacteria that floats around in water; does not adhere to anything

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17
Q

Is there planktonic bacteria in saliva? Why?

A

No there is not

Saliva has a high turnover rate

  • spitting, swallowing disrupts the biofilm so cannot mature
  • biofilm will not grow unless has something to adhere to
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18
Q

In what form do bacteria that cause medical problems attach to a surface?

A

Sessile

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19
Q

What are the two components of a biofilm?

A

Microorganisms + Extracellular matrix

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20
Q

What is the protein secreted in the ECM of oral biofilm?

A

lipopolysaccharide

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21
Q

What are the three functions of ECM of biofilm?

A
  1. protect bacteria
  2. hold biofilm together
  3. anchors biofilm to surface
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22
Q

Circulatory system of biofilm

A

Biofilm once matured has water channels incorporated where water can pass through

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23
Q

What are the three stages of Biofilm formation?

A
  1. Attachment
  2. Growth to mature biofilm community
  3. Detachment, to seed new biofilm formation
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24
Q

Describe polymicrobial communities

A
  • Can be formed by single bacterial species but often include many species of bacteria
  • may include fungi, algae, protozoa
  • very sophisticated
  • bacteria communicate with each other within biofilm
  • cooperative activities
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25
Q

What are the cooperative activities that go on in a biofilm?

A

bacteria provide nutrients for one another

bacteria provide metabolic function for one another (get rid of toxins)

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26
Q

How do bacteria detect each other?

A

quorum sensing

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27
Q

T/F: when bacteria attach to the surface they turn on a different set of genes

A

true

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28
Q

Biofilms are stable, slow growing communities that are resistant to four things…

A
  1. antibiotics
  2. mechanical disruption
  3. host defenses
  4. antisepsis
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29
Q

T/F: control measures use on suspended bacteria are as affective on biofilms

A

false

control measures used on suspended bacteria are LESS effective on biofilms
Ex: dose of antibiotics must be increase 1000x

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30
Q

What is quiescent bacteria? Why do these type of bacteria pose a problem for disrupting biofilm?

A

Quiescent bacteria are “sleeping” bacteria
They have no metabolic activity

Antibiotics do not recognize these bacteria because they are not active so they do not kill these bacteria.
Then later these bacteria “wake up” and begin to produce biofilm again

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31
Q

What are four human oral problems that are caused by biofilm?

A
  1. periodontitis
  2. caries
  3. osteomyelitis
  4. osteonecrosis
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32
Q

Three primary mechanism for biofilm antimicrobial resistance

A
  1. slowing of diffusion
  2. “persister cells” (quiescent bacteria)
  3. close proximity and exchange of resistance genes
33
Q

some oral diseases are cause by invasive bacteria. where does this begin? what is an example?

A

Ex: cellulitis

starts with biofilm on tooth and then becomes invasive

34
Q

What are three places bacteria can adhere?

A
  1. host surfaces
  2. other bacteria
  3. extracellular matrix
35
Q

what are two important functions of alpha amylase?

A
  1. good in binding streptococcus strains

2. helps in agglutinating saliva

36
Q

What are common measure used to disrupt bacterial adherence in the mouth?

A

mechanical disruption:

brushing, flossing daily

37
Q

place periodontal pocket, supragingival plaque, air, and closed mouth’s oxygen levels in order from high to low

A
  1. air
  2. close mouth
  3. supragingival plaque (usually)
  4. periodontal pocket
38
Q

what is the definition of positive Eh aerobes

A

high oxygen, microbes have high potential to oxidize or reduce

39
Q

what is the definition of negative Eh anaerboes

A

low oxygen, microbes do not readily oxidize or reduce

40
Q

obligate aerobe

A

requires oxygen for growth

41
Q

facultative anaerobe

A

can switch between aerobic and anaerobic metabolism

42
Q

microaerophillic microorganisms

A

require low levels of oxygen (will not tolerate high levels)

43
Q

aerotolerant anaerobes

A

anaerboic metabolism but can tolerate oxygen

44
Q

obligate anaerobes

A

do not use oxygen as a nutrient and oxygen is toxic

45
Q

what is the mechanism of oxygen toxicity

A

causes oxidation of membrane lipids and destroys cell integrity; oxidizes sulfhydryl groups in enzyme which cause cross linking and inactivity of bacteria

46
Q

anaerobes have genetic inability to make 3 enzymes….

A

superoxide dismutase, catalase, and peroxidases

47
Q

what is the function of superoxide dismutase, catalase, and peroxidases

A

detoxify oxygen radicals in the presence of oxygen

if bacteria do not have these (anaerobes) then these radicals will cause damage to cell

48
Q

what happens to the nature of bacteria as the biofilm gets thicker?

A

the bacteria becomes more anaerobic (negative Eh) because less oxygen is present (sheltered)

49
Q

where are two places that anaerobic bacteria are commonly found?

A
  1. sulcus

2. matured coronal plaque

50
Q

which two bacteria are found in supragingival plaque?

A
  1. facultative anaerobe

2. microaerophillic bacteria

51
Q

what is special about fusobacterium species in terms of oxygen?

A

they scavenge oxygen making the area around them more anaerobic for other bacteria

52
Q

what common therapy is used to kill off oxygen sensitive bacteria?

A

treatment with hydrogen peroxide

53
Q

what is the normal oral pH

A

7.0

54
Q

at what pH does demineralzation of enamel begin

A

5.5

55
Q

what can cause low pH

A

foods/drinks that are acidic
acid reflux in patients
sugar that is converted to lactic acid

56
Q

what are two consequences of low pH

A
  • begining of deminerlization so can cause caries

- kill off good bacteria

57
Q

low pH inhibits most oral species except…

A

Strep and lactobacilli

58
Q

what are the three things needed for caries to occur

A
  1. bacteria
  2. substrate
  3. vulnerable tooth
59
Q

what are exogenous nutrients and what do they provide for?

A

anything ingested
-food (soluble carbs and AA readily taken up by bacteria; starches and proteins that are sticky attach to tooth surface and allow enough time to for bacteria to get nutrients)
supragingival bacteria
DO NOT reach the sulcus

60
Q

What are endogenous nutrients and what do they provide for?

A
  • glycoproteins, inorganic salts, amino acids, glucose, and vitamins in saliva provide for supragingival bacteria
  • shed host cells
  • crevicular fluid contains serum proteins (transudate), AA, glucose, vitamins, hemin, hormones that provide for subgingival bacteria
61
Q

T/F: you need to sugar to get plaque/calculus

A

False

Tube fed patients were found to have tons of plaque but no caries

62
Q

what type of nutrients are needed for caries?

A

exogenous nutrients

-has to come from food you eat

63
Q

Antibodies used for specific immunity

A

sIgA and IgG

64
Q

what does sIgA do

A

in saliva and prevents adhesion

65
Q

what does IgG do

A

in crevicular fluid and works against periodontally important organisms

66
Q

what are 3 general jobs of antibodies in specific immunity

A
  1. inhibit colonization (block binding sites)
  2. act as opsonins
  3. activate complement system
67
Q

what is involved in innate immunity (5)

A
  1. epithelial barrier
  2. saliva flow
  3. antimicrobial peptides
  4. neutrophils
  5. complement proteins from crevicular fluid
68
Q

what is an extremely vulnerable site in the tissue related to the teeth

A

junctional epithelium

lots of neutrophils lined up there

69
Q

what are 2 major salivary proteins and their function

A

a-amylase: digest starches and bind bacteria

mucins: lubricant

70
Q

what are 5 salivary defenses (minor proteins) and their functions

A

salivary lysozyme: destroy bacterial cell wall by digesting peptidoglycan

salivary lactoferrin/serum transferrin: these proteins bind iron to keep away from bacteria
(in toothpastes)

sialoperoxidase system: make superoxide radicals which inactivate bacterial enzymes

antimicrobial peptides: act against bacteria and yeast

acidic proline rich proteins and statherin: coat surface to prevent hyroxyapatite crystals from growing

71
Q

what are 2 mechanisms that help maintain the integrity of the tooth

A

salivary buffering

pellicle proteins

72
Q

what is a peridontal pathogen and causes the most damage

A

p gingivalis

73
Q

what does p gingivalis need to survive

A

vitamin K3

74
Q

what converts lactate to proprionate and raises pH for acid sensitive strep

A

veillonella

75
Q

how does carbon dioxide play a role in altering the environment by bacteria

A

bacteria including peptostreptococci and eubacteria generate CO2 which enhances the growth of other bacteria

76
Q

how does the removal of oxygen by bacteria alter the environment

A

fusobacterium species sequesters oxygen to make a more anaerobic environment so bacteria like t. forsythia can survive

77
Q

what are bacteriocins

A

bacterial inhibitory factor produced by example strep salvarius to inhibit other bacteria from growing (enocin)

78
Q

what is colonization resistance

A

established organisms can prevent the growth of new organisms

79
Q

why is collecting saliva samples for clinical diagnostic tests controversial?

A

saliva contains bacteria shed from all ecosystems

sample can be diluted because not all bacteria in the mouth are floating around (most are adhered to a surface)

Pedo Exam (7 decks)

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