Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CSA > microbiology part 1 > Flashcards

microbiology part 1 Flashcards

to review the microbial aetiology of caries and provide context for preventative approach objectives: revisit properties of dental biofilm review the methods to characterise the oral microbiome assess the evidence for the role of micro-organisms in caries describe the main causative bacteria define the properties of cariogenic bacteria

1
Q

what are dental biofilms

A

they are natural and beneficial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

how many species are present in the dental biofilm

A

700+ species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the biofilm composed of

A

bacteria
viruses
fungi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what does the biome help with

A

with key functions
helps to regulate the immune system
and helps with host defences

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is desquamination

A

the shedding of epithelial cells- reduces the bacterial load

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

examples of non shedding surfaces

A

teeth
dentures
implants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the bacterial load like on non shedding surfaces

A

it is high unless you remove the load by eg brushing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how can we tell which bacteria are beneficial or harmful

A

by traditional culture such as

grow the organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what are the issues with traditional culture

A

laborious
expensive
only half the species in the mouth grow on blood agar
very time consuming- need to do multiple tests and isolate the species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what are the issues with microscopy

A

only will tell you the shape of the species( cell morphology)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what does FISH stand for

A

fluorescent in situ hybridisation- can help recognise a few species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are the molecular approaches to identify the species in the microbiome

A

HOMIM (human oral microbiome identification microarray )
DNA-DNA hybridisation
PCR
high throughput whole genome sequencing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the gold standard to see what species an organism is

A

high throughput whole genome sequencing- and put into the database and you can see which organism is present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is metagenomics

A

complex clinical sample such as plaque
extract DNA
cut DNA
sequence and then the short fragments will make a long sequence
tested across a database and we can see which species are present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what does metatranscriptonomics look at

A

RNA to see which proteins are transcribed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is HOMD

A

human oral microbiome database

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

how is the bacteria in the dental biofilm organised

A

structurally organised

functionally organised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

why are bacteria in the biofilm functionally organised

A

so that the aerobic organisms are nearer the surface for O2

and anaerobic at the base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what are the features of the dental biofilms

A 
concerted and collaborative metabolism 
food chains
environment modification
matrix formation
cell-cell signalling
complex interactions- balance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

why are dental biofilms helpful

A

they help get rid of harmful organisms in the mouth due to pathogen exclusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

how can the load of helpful bacteria in the dental biofilm be reduced

A

due to long term antibiotic therapy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what can be the result of long term antibiotic therapy

A

overgrowth of yeasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

bacteria from which organ can cause a inflammatory reaction

A

gut and the mouth but rare

eg Crohns disease in the gut

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

why do we rarely see inflammatory reaction in the mouth

A

because the bacteria communicate between one another and the host

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what is the entero salivary nitrate circulating system

A

where nitrate from green vegetables is reabsorbed from the gut and appears in saliva and the beneficial bacteria can break it down to nitrite which modifies blood pressure . and nitrite that is swallowed becomes acidified nitric oxide which is antibacterial and stimulates mucus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

where does the body get nitrate from

A

from green veggies we eat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what does the nitrate get converted to

A

get converted into nitrite by beneficial bacteria in the oral cavity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

why is nitrite good

A

it can reduce blood pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what does XS nitrite that is swallowed get converted into

A

acidified nitric oxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

where is the XS nitrite converted

A

in the stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

why is acidified nitric oxide good

A

due to the fact it stimulates mucus production which protects the stomach lining and it is antibacterial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

examples of bacteria seen in carious lesions

A

strep mutans
lactobacillus
other acidogenic/tolerating bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

which bacteria are seen in health

A 
strep oralis/mitis 
fusobacterium nucleatum 
actinomycetes spp
haemophillus spp
neisseria spp
34
Q

why is caries multifactorial

A

as it has many components such as:
susceptible host
environmental factor
key oral organisms

35
Q

what factors are included in environmental factors

A

cariogenic diet
poor oral hygiene
low saliva flow rate

36
Q

what happens to older peoples flow rate of saliva

A

decreases- side effect if medication eg blood pressure medication

37
Q

what factors are including in confounding factors

A

fluoride availability
diverse natural microbiota
non specific virulence traits

38
Q

what is the evidence that microbes are involved in the aetiology of dental caries

A

gnotobiotic( known life) animal studies:artificial conditions where they are not exposed to organisms
and then micro-organisms are introduced and we see the effect

39
Q

gnotobiotic animal studies showed

A

specificity of certain microrganisms- eg lactobacilli causes caries
diet- we do not have caries if fermentable sugars are not present
transmission- from infected animal to non infected
antim
antimicrobial agents- effective antimicrobials prevent caries

40
Q

why ca we not do germ free ethical studies on humans

A

due to ethical reasons

41
Q

what is a cross sectional study

A

where we take a group of people- at one time point

sample of plaque and analyse for which species and see where caries is or isn’t

42
Q

what is the issue with cross sectional studies

A

cheap but only show associations- do not know certainly if the bacteria found in the lesion caused the lesion or grew as a consequence of the lesion

43
Q

what is a longitudinal studies

A

small group of people- caries free
choose caries prone site
a % of those people should develop caries in that area in a few years
monitor every 3-6 months for several years
compare the microorganisms before during and after

44
Q

what are the disadvantages of longitudinal studies

A

expensive

takes a lot of time- not many done

45
Q

Vaccination

A

Vaccination against strep mutans in rodents and primates

46
Q

Why are vaccinations for varies not introduced to humans

A

There were a few side effects and the public confidence in vaccines was little so the cost of clinical trials
But fluoride was having an effect
Vaccine hasn’t been tested in human clinical trials

47
Q

what serotype is found of strep mutans

A

c
e
f

48
Q

what serotype is found of strep srobinus

A

d

g

49
Q

what species of actinomyces is present

A

a naeslundii
a odontolyticus
a isrealii

50
Q

what species of bifidobacteria

A

bifidobacterium

51
Q

which species of candida is found

A

c albicans

52
Q

describe strep mutans

A

gram +ve cocci
found on hard surfaces- non shedding surfaces
implicated in initiation of caries

53
Q

describe lactobacillus

A

gram +ve rods

implicated in advanced dental caries

54
Q

describe bifidobacterium ( more recent years)

A

gram +ve rods
branched cells
recently implicated caries

55
Q

what are the difficulties with trying to associate microorganisms with dental caries

A

disease occurs at sights where there is natural biome
difficult to correlate microbiota to enamel status
lesions can remineralise
pathogenic traits are relatively non specific
multifactorial nature of caries

56
Q

what bacteria is found at caries sites

A

strep mutans but not always

in both proportions and isolation frequencies

57
Q

which bacterias have an inverse relationship

A

between strep mutans and strep sanguinis

58
Q

what % of caries had more than 10% MS

A

71%

59
Q

what percentage of caries free fissures had no detectable MS

A

70%

60
Q

when does MS first start to show

A

early demineralisation

61
Q

can caries also occur if MS is not present

A

YES

62
Q

examples of acidogenic bacteria

A

strep mitis

strep oralis

63
Q

give examples of lactate utilising bacteria

A

veillonella

64
Q

what is lactate converted to

A

propionate or acetate

65
Q

describe veillonella

A

gram negative coccus
anaerobic
utilises lactic acid in plaque

66
Q

name base generating species

A

s salivarius will make the pH basic when urea is present
s sanguinis will make the pH basic when arginine is present
a naeslundii will make the pH basic when urea is present

67
Q

when will s salivarius make the ph basic

A

when urea is available

68
Q

when will s sanguinis make the ph basic

A

when arginine is present

69
Q

when a naeslundii will make the ph basic

A

when urea is available

70
Q

which species is found in people with low caries or no caries

A

strep dentisani

strep A12

71
Q

what do both strep dentisani and strep A12 do

A

they are arginolytic meaning they break down arginine into ammonia snd inhibits strep mutans

72
Q

what can strep dentisani and strep A12 be used as

A

As probiotic

73
Q

describe the urea to ammonia conversion

A

urea + h20—–> ammonia + CO2 by the enzyme urease

74
Q

describe the arginine deiminase system

A

arginine—->citulline+ ammonia—-> ornithine + carbamyl- P—-> ATP+ C02 + ammonia

75
Q

what bacteria is associated with childhood caries/nursing bottle caries

A

mutans streptococci

lactobacilli

76
Q

which bacteria is associated with root surface caries in early studies

A

actinomyces spp

77
Q

which bacteria is associated with root surface caries in later studies

A

MS

lactobacilli

78
Q

which bacteria is associated with root surface caries in recent studies

A

diverse microbiota
actinomyces spp- A israelii and A gerensceriae
MS
gram negative rods

79
Q

what bacteria do you find in infected dentine

A

MS
lactobacilli
actinomyces spp- A israelii and A gerensceriae
gram negative anaerobic rods - prevotella

80
Q

what molecular changes do you find in infected dentine

A

strep mutans
eubacterium saburreum
diverse array of lactobacillius
diverse array of prevotella

81
Q

what else is found in infected dentine

A

acidogenic bacteria

combined with proteolytic and collagenolytic bacteria

82
Q

characteristic of cariogenic bacteria

A

rapid sugar transport and acid production PEP-PTS
aciduricity
EPS
IPS

CSA (51 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions