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Microbiology > M9- Gram postive oral bacteria > Flashcards

M9- Gram postive oral bacteria Flashcards

1
Q

Name the major genera of Gram positive oral bacteria.

A
  • Streptococci spp (Facultative & Obligate anaerobes)
  • Staphylococci spp (Facultative anaerobes)
  • Actinomyces spp.( Facultative anaerobes & Obligate anaerobes)
  • Lactobacillus spp. (Facultative anaerobes)
  • Eubacterium spp. (Obligate anaerobes, Isolated from destructive periodontal disease)
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2
Q

What does CNS stand for and what bacteria is it associated with?

A
  • Coagulase negative staphylococci

- Staphylococci

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3
Q

what do oral staph pose a risk for?

A

oral disease and cross contamination

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4
Q

how sensitive is staphylococci species to methicillin?

A

90%

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5
Q

After streptococci , what is the next most important group of bacteria involved in dental caries?

A

lactobacilli

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6
Q

What is the shape of lactobacillus’s rods?

A

pleomorphic

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7
Q

why are lactobacilli described as acidogenic and acidic?

A

survive and reproduce under acid conditions .. pH 5.5

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8
Q

how adhesive is lactobacilli?

A

poor adhesion properties so late colonisers (EPS important)

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9
Q

Name the 3 main groups of lactobacilli.

A
  • Homolactic fermenters (>65%)
  • Heterolactic fermenters
  • Facultative heterolactic fermenters
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10
Q

Describe homolactic fermenters.

A

– produce only lactic acid from sugar

– Embden-Meyerhof pathway of glycolysis

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11
Q

Describe heterlactic fermenters.

A

– equal amounts of lactic acid, acetic acid (or ethanol) & CO2

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12
Q

Describe facultative heterolactic fermenters.

A

– normally homolactic fermenters

– can switch to heterolactic fermentation (induce)

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13
Q

what is the most damaging product of pyruvate?

A

lactic acid

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14
Q

Name common lactobacillus species.

A
  • lactobacillus casei Gp (most common) (homofermenter)
  • lactobacillus acidophilus (homofermenter)
  • lactobacillus fermentum (heterofermenter)
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15
Q

what do lactobacillus species compete with?

A

mutans

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16
Q

what is dentine caries associated with?

A

deep carious lesions (low pH environment)

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17
Q

what do levels of lactobacilli in salvia correlate with?

A

carbohydrate intake

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18
Q

what are dentine caries test used for?

A

to follow patients over time &/or in combination with other caries predictive tests

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19
Q

what happens to lactobacilli as mutans sterptococci falls?

A

tend to increase

20
Q

where are high numbers of lactobacilli found?

A

carious dentine

21
Q

what is there is a positive correlation between?

A

numbers of lactobacilli and carious lesions

22
Q

what role does lactobacilli have in initiating dimineralization?

A

No major role in initiating demineralization, important in progression once low pH established

23
Q

what are caries susceptibility tests used to determine?

A

Determine the numbers of cariogenic bacteria in saliva

S. mutans & Lactobacilli

24
Q

what is targeted on high risk patients?

A

preventive measures (dietary advice, fissure sealants, fluoride varnishes etc.)

25
Q

How can lactobacilli be protective?

A

• L. rhamnosus milk protected pre-school children
• L. casei & L. rhamnosus reduced S. mutans
colonisation

26
Q

what are actinocymes?

A

Gram +ve pleomorphic rods

27
Q

what is actinomyces a major proportion of?

A

microflora

28
Q

how is actinomyces arranged?

A

singly, in pairs, short chains or clumps

29
Q

does actinomyces form pores?

A

can grow as branched network of hyphae but do not form spores

30
Q

what are other features of actinomyces ?

A

– anerobic or facultative anaerobes (CO2 for Optimal Growth)
– Some possess fimbriae which aid in adherence and aggregation
– non motile

31
Q

Where is actinomyces mainly found?

A

in the mouth, in dental plaque, in tonsil crypts (some in the female genital tract)

32
Q

Name 2 actinomyces in the mouth.

A

– A.naesludii
– A.odontolyticus
(Found in supra & subgingival plaque)

33
Q

what historically is actinomyces associated with?

A

root surface caries

34
Q

Describe actinomyces naeslundi.

A

• produce extracellular slime & fructans from
sucrose
• found in large numbers in dental plaque in approximal and root surfaces
• able to cause periodontal disease when introduced in gnotobiotic hamsters
• Historically associated with enamel & root surface caries
• may cause actinomycosis

35
Q

Describe Actinomyces israelii.

A

• Mouth, dental plaque & female genital tract,
• Strict anaerobe
• opportunistic & most likely to cause actinomycosis
• infection endogenous arising from the normal flora
~60% head and neck region
~20% are abdominal ~20% in the lungs

36
Q

What is thick fluid expressed from the sinuses known as?

A

sulphur granules ( yellow, granular ,particulate)

37
Q

what are granules in pus?

A

pathogenic (indicator of disease)

38
Q

Pus is aggregations of what?

A

actinomyces filaments

39
Q

What is in >80 % of all actinomyces lesions?

A

A. Israelii

40
Q

What is the treatment for actinomyces lesions?

A
  1. Removal of original dental focus of infection
  2. incision and drainage of lesion
  3. long term antibiotic treatment:
    penicillin/amoxycillin (up to 6 weeks)
41
Q

describe features of eubacterium species.

A 
•  Diverse
•  Obligate anaerobes
•  Bacilli to Filamentous
•  Gram variable
•  Large number of unculturable species from abscesses
•  Recent association with progression of dental caries.
•  Asaccharolyic species
implicated in periodontal
disease
42
Q

what other gram + genera are found in the mouth and in dental plaque?

A
  • Propionibacterium
  • Rothia
  • Corynebacterium
43
Q

Describe Propionibacterium propionicus.

A

– produces propionic acid as the major fermentation product
– mouth, dental plaque and calculus
– Similar to Actinomyces israelii
• causes actinomycosis-type lesions & tear duct infections

44
Q

Describe Propionibacterium acnes.

A

– inhabits the skin, acne lesions and soft tissue abscesses.
– Found in periodontal pockets in association with periodontal disease

45
Q

Describe rothia dentocariosa.

A
  • originally isolated from carious teeth (progression of lesion)
  • pleomorphic rods often found in long chains
  • colonises supra-gingival plaque
  • opportunistic pathogen causing a variety of infections including endocarditis
46
Q

Describe corynebacterium matruchotii.

A

– associated with dental plaque
– has a very characteristic “whip handle” morphology
– may be a focus in dental plaque for the initiation of calculus formation
– one study found only in children with active caries

47
Q

Describe distribution of key species in plaque.

A

Actinomyces;
– species associated with higher populations in supra-
gingival plaque samples

Propionobacterium
– Speciessimilarassociation (distribution) in supra & sub gingival plaque

Eubacterium;
– Speciesassociation (distribution) with sub gingival plaque (anaerobic)

Streptococci;
– Generaassociationwitha range of environments

Microbiology (30 decks)

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