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ICP > L4: The microbial flora of dental plaque > Flashcards

L4: The microbial flora of dental plaque Flashcards

1
Q

what is colonization resistance?

A

when normal flora acts to exclude pathogens and protect the host

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2
Q

on what sites of the body can microbial colonosation take place?

A

hard & non-shedding surfaces

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3
Q

tongue crypts have a ____ redox potential

A

low

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4
Q

what do the low redox potential of tongue crypts mean for gram -ve anaerobes?

A

acts as a reservoir for gram -ve anaerobes = periodontal disease

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5
Q

____ and ___ _____ of saliva at different oral sites may influence caries susceptibility

A

flow and ion content

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6
Q

what is the role of glycoproteins in saliva?

A
  • influeneces aggregation and adhesion of bacteria to oral surfaces
  • interacts with other salivary components and immune defences
  • acts as a primary source of nutrients for normal microflofora
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7
Q

what is the role of urea and free amino acids in saliva?

A

they are metabolised to lead to an increased pH (counteracts acid production after carb intake)

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8
Q

what is GCF and what does it do?

A

gingival crevicular fluid; regulates the microflora of the gingival crevice during health and disease

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9
Q

what are the non-specific factors of saliva?

A
  • physical removal by flow of saliva & GCF
  • swallowing
  • LYSOZYME in saliva hydrolyses peptidoglycan in bacterial cell walls
  • LACTOFERRIN - high affinity iron - binding glycoprotein
  • SIALOPEROXIDASE - salivary peroxidase enzyme system generates inhibitors of bacterial glycolysis
  • antimicrobial peptides (i.e. histatins - histadine rich peptides) that regulate microorgansm levels
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10
Q

what are the specific factors in saliva

A
  • intra-epithelial lymphocytes, langerhan cells & IgA found within the mucosa - acts as a barrier to penetratng antigens
  • secretory IgA - agglutinates bacteria, modulates enzyme activity & inhibits adherence of bacteria to buccal epithelium and enamel.
  • CGF conatins IgG, IgM, IgA, complement and neutrophils
  • specific Ab production stimulated by bacterial antigens at the gingival margin or on oral mucosa
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11
Q

stroptococcus is gram ___

A

+ve

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12
Q

extracellular polysaccharides are associated with

A

plaque formation

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13
Q

what are the 2 strains present in the streptococcus mutans group?

A

S.mutans

S.sobrinus

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14
Q

what 2 isolates are present in the aetiology of enamel caries in children and young adults?

A

dental caries

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15
Q

what are the two main strains of the Streptococcus salivarius group?

A

• S. salivarius – common isolate from most areas
esp. mucosal surfaces.
• S. vestibularis – isolated mainly from vestibular
mucosa of mouth.

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16
Q

where is s. vestibularis found?

A

mainly at the vestibular mucosa of the mouth

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17
Q

what are the 3 main strains of the streptococcus milleri group?

A

S.constellatus, S.intermedius & S.anginosus

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18
Q

what type of pathogens are the streptococcus milleri group? (S.constellatus, S.intermedius & S.anginosus)

A

Opportunistic pathogens – important cause of

purulent disease

19
Q

name 2 strains of the streptococcus oralis group?

A

S.sanguinis, S.gordonii

20
Q

what type of pathogens are the streptococcus oralis group? (what type of pathogens are the streptococcus milleri group? (S.sanguinis, S.gordonii)

A

• Opportunistic pathogens – isolated frequently

from infective endocarditis

21
Q

what type of bacteria is Peptostreptococcus spp (P. anaerobius)

A

obligate anaerobes

22
Q

where is Peptostreptococcus spp (P. anaerobius) recovered from?

A

Recovered from dental plaque esp. in
advanced periodontitis, carious dentine,
infected pulp chambers and root canals, and
dental abscesses.

23
Q

where is Enterococcus (E.faecalis) recovered from?

A

Recovered in low nos. from several oral

sites – involved in root canal infections.

24
Q

where are Staphylococci and micrococci found?

A

not members of the resident oral microflora – may be present transiently

25
Q

what is Rothia?

A

aka Stomatococcus mucilaginosus
a species of Gram-positive, round- to rod-shaped bacteria that is part of the normal community of microbes residing in the mouth and respiratory tract.

26
Q

where is Rothia rothia

(Stomatococcus) mucilagenous found?

A

isolated

from tongue

27
Q

Actinomyces

A

gram +ve

Forms a major portion of plaque microflora esp. at
approximal sites – also colonise gingival crevice
– nos increase with gingivitis and are associated
with root surface caries. A.israelii can act as
opportunistic pathogen and cause actinomycosis

28
Q

Eubacterium

A 
gram +ve
• Poorly-defined genus – obligate
anaerobes
• Found in subgingival plaque esp. in
periodontitis
• Often isolated from infections of head,
neck and lung and necrotic dental pulp
29
Q

Lactobacillus

A

gram +ve
• Commonly isolated although comprise <1% of
total cultivable flora
• Little known of preferred habitat in normal
mouth
• Proportions and prevalence increase at
advanced caries lesions of enamel and root
surface – highly acidogenic organisms

30
Q

Propionibacterium

A

• Obligate anaerobes – several spp. reported from
mouth incl P. acnes in dental plaque

P. propionicus – opportunistic pathogen &
isolated from actinomycosis

31
Q

Neisseria

A 
gram -ve
• Aerobic – isolated in low numbers from
most sites in mouth
• With S.oralis-group are among early
colonisers of a clean tooth surface
32
Q

Veillonella

A

gram -ve
• Strict anaerobes
• Isolated from most surfaces in mouth
• Highest numbers in dental plaque
• Do not metabolise carbohydrates – utilise
intermediary metabolites (esp. lactate) as
energy sources
• May play important role in ecology of dental
plaque and in aetiology of dental caries

33
Q

gram -ve rods; Facultative/Capnophilic bacteria:

A

• Haemophilus spp – common in saliva, on
epithelial surfaces, and in dental plaque.
• Eikenella corrodens – isolated from wide range
of oral infections.
• Capnocytophaga spp – found in sub-gingival
plaque – opportunistic pathogens.
• Aggregatibacter (Actinobacillus)
actinomycetemcomitans – found in aggressive
periodontitis – uncommon in plaque from healthy
sites.
• Simonsiella – isolated from epithelial surfaces.

34
Q

Gram -ve Rods: obligate anaerobic bacteria

A

• Comprise a large proportion of the microflora of
dental plaque
Black-pigmented; Porphyromonas spp
(asaccharolytic), Prevotella spp (saccharolytic)
Porphyromonas gingivalis
• found at subgingival sites (esp. periodontal
pockets) highly virulent
• produces many putative virulence factors
• rarely found in health

35
Q

Prevotella

A 
gram -ve
• Isolated from dental plaque esp. subgingival
sites
• Some spp. associated with periodontal
disease and abscesses
36
Q

Fusobacterium

A

gram -ve
• Asaccharolytic
• Certain spp. found in normal gingival crevice
and other recovered mainly form periodontal
pockets.
Other oral Gram-negative anaerobic and
microaerophilic bacteria inc Leptotrichia,
Campylobacter, Selenomonas, Centipeda

37
Q

Spirochaetes

A

gram -ve
• Numerous in sub-gingival plaque – several
morphological types – numbers increase in
periodontal disease; role remains unclear
Mycoplasma
• Pleomorphic bacteria with non-rigid outer
membrane – isolated from saliva, oral
mucosa and dental plaque

38
Q

Fungi - what candida spp makes up the largest proportion of the oral fungal flora?

A

C.albicans

39
Q

Viruses

A

• Herpes Simplex (type I) most common virus
detected in the mouth (occasionally detected
in the absence of cold sores)
• Cytomegalovirus present in the saliva of
most individuals
• Hepatitis & Human Immunodeficiency
Viruses – present in the saliva of
asymptomatic individuals
• Coxsackie viruses & Papilloma – both
groups normally associated with lesions

40
Q

what is the most common virus detected in the mouth;?

A

Herpes Simplex (type I)

41
Q

what virus is present in the SALIVA of most individuals?

A

Cytomegalovirus

42
Q

what virus is present in the saliva of

asymptomatic individuals?

A

Hepatitis & Human Immunodeficiency

Viruses

43
Q

what 2 viruses are normally associates with lesions?

A

Coxsackie viruses & Papilloma

ICP (20 decks)

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