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Year 2 CSA > Microbiology of caries > Flashcards

Microbiology of caries Flashcards

1
Q

what are dental biofilms?

A

natural and beneficial

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2
Q

how many species are present in a Biofilm?

A

700+

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3
Q

what is the biofilm composed of?

A

bacteria
viruses
fungi

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4
Q

what does the biome help with?

A

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

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5
Q

what is desquamination

A

the shedding of epithelial cells- reduces the bacterial load

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6
Q

examples of non shedding surfaces

A

teeth
dentures
implants

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7
Q

what is the bacterial load like on non shedding surfaces

A

it is high unless you remove the load by eg brushing

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8
Q

how can we tell which bacteria are beneficial or harmful

A

by traditional culture such as
grow the organism

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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

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10
Q

what are the issues with microscopy

A

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

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11
Q

what does FISH stand for

A

fluorescent in situ hybridisation- can help recognise a few species

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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

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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

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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

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15
Q

what does metatranscriptonomics look at

A

RNA to see which proteins are transcribed

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16
Q

what is HOMD

A

human oral microbiome database

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17
Q

how is the bacteria in the dental biofilm organised

A

structurally organised
functionally organised

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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

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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

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20
Q

why are dental biofilms helpful

A

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

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21
Q

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

A

due to long term antibiotic therapy

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22
Q

what can be the result of long term antibiotic therapy

A

overgrowth of yeasts

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23
Q

bacteria from which organ can cause a inflammatory reaction

A

gut and the mouth but rare
eg Crohns disease in the gut

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24
Q

why do we rarely see inflammatory reaction in the mouth

A

because the bacteria communicate between one another and the host

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25
Q

what is the entero salivary nitrate circulating system

A

where nitrate from green vegetables is reabsorbed from the gut/ intestines 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

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26
Q

where does the body get nitrate from

A

from green veggies we eat

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27
Q

what does the nitrate get converted to

A

get converted into nitrite by beneficial bacteria in the oral cavity

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28
Q

why is nitrite good

A

it can reduce blood pressure

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29
Q

what does XS nitrite that is swallowed get converted into

A

acidified nitric oxide

30
Q

where is the XS nitrite converted

A

in the stomach

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

32
Q

examples of bacteria seen in carious lesions

A

strep oralis/mitis
fusobacterium nucleatum
actinomycetes spp
haemophillus spp
neisseria spp

33
Q

why is caries multifactorial

A

various factors can contribute to the disease

34
Q

what factors are included in environmental factors

A

cariogenic diet, poor oral hygiene, low saliva flow

35
Q

what are the confounding factors?

A

fluoride availability, diversity of microbiota, non specific virulence traits

36
Q

what evidence do we have for the role of microbes in causing caries?

A

gnotobiotic animal studies, human epidemiology studies and vaccination

37
Q

what is a gnotobiotic animal study?

A

controlled research environments where no microbes are present or at least present are known and are controlled vigoruously eg. gnotobiotic animals such as rats must be completely devoid of microbes in their bodies

38
Q

what does the gnotobiotic rat study show us about caries

A

when they were infected with just strep much and sugars they showed caries
therefore shows;
1) some bacteria are more cariogenic than others
2) diet and particular fermentable sugars
3) transmission from animal to animal
4) antimicrobial agents

39
Q

what does human epidemiology studies show us about caries? what are the 3 methods we use to investigate?

A

1) cross sectional study= cheaper but only show us associations
2) longitudinal study= shows cause and effect relationships between microbe and disease
3) vaccination= carried out by rodent and primates

40
Q

what serotype is found of strep mutans

A

c e and f

41
Q

what stereotypes found in s. sobrinus

A

d and g

41
Q

what stereotypes found in s. sobrinus

A

d and g

41
Q

what stereotypes found in s. sobrinus

A

d and g

41
Q

what stereotypes found in s. sobrinus

A

d and g

41
Q

what stereotypes found in s. sobrinus

A

d and g

42
Q

describe strep mut

A
  • Gram positive cocci/short rods
  • Found on hard non-shedding surfaces
  • Implicated in initiation of caries
43
Q

give eg of actinomyces

A

o A. naeslundii
o A. odontolyticus
o A. israelii or A. gerencseriae

44
Q

give eg of actinomyces

A

o A. naeslundii
o A. odontolyticus
o A. israelii or A. gerencseriae

44
Q

give eg of actinomyces

A

o A. naeslundii
o A. odontolyticus
o A. israelii or A. gerencseriae

45
Q

describe Lactobacillus

A

Lactobacillus – gram positive rod, implicated in advanced dental caries

46
Q

describe bifidobacterium

A

Bifidobacterium – gram positive rod, branched cells, recently implicated in caries

47
Q

name a species of candida

A

c. albicans

48
Q

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

A

1) disease occur at sites with natural, diverse microbiota
2) pathogens found at “healthy” sites often as minor component of multi- species biofilms
3) difficult to correlate microbiota to enamel status= once lesions appear they can be remineralised
4) pathogenic traits are non specific and many factors contributing to caries

49
Q

what bacteria is found at caries sites according to cross sectional studies

A

s. mutans

50
Q

according to cross section studies which bacterias have an inverse relationship

A

MS and s. sanguinis

51
Q

what are the most caries prone sites

A

fissures and fissures that had Mutan Streptococci indicated carious fissures.

52
Q

what % of caries had more than 10% MS

A

71% therefore 30% caries fissures had lower or no MS

53
Q

what percentage of caries free fissures had no detectable MS

A

70%

54
Q

when can MS occur

A

first signs of demineralisation

55
Q

can caries also occur if MS is not present and what does this show

A

yes
that other species have a role in caries progression eg. ;lactobacilli in advanced lesions

56
Q

examples of acidogenic bacteria

A

s. mitis and s.oralis

57
Q

give examples of lactate utilising bacteria

A

Veillonella utilises lactic acid in plaque and converts it into a weaker acid, reducing demineralisation.

58
Q

give eg of base producing species

A

Streptococcus salivarius, A. naeslundii and s. sanguinis

59
Q

what can s. salivarius and A. naeslundii hydrolyse urea into?

A

ammonia and co2

60
Q

what is the role of s. sanguinis

A

utilises the arginine deaminase system

61
Q

what bacteria is associated with childhood caries/nursing bottle caries

A

MS and lactobacillus

62
Q

which bacteria is associated with root surface caries in early studies

A

actinomyces spp

63
Q

which bacterias are associated with root surface caries in later studies

A

MS and lactobacilli

64
Q

which bacterias are associated with root surface caries in recent studies

A

diverse microbiota
actinomyces spp
MS
gram negative rods

65
Q

what molecular changes do you find in infected dentine

A

31 new taxa
data suggests combinations of acidogenic bacteria combined with proteolytic and collagenolytic anaerobes

66
Q

what bacteria do you find in infected dentine

A

MS Lactobacilli actinomycetes spp (a. israelii A. gerencseriae gram negative anaerobic rods

Year 2 CSA (6 decks)

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