M9- Gram postive oral bacteria

Question 1

Name the major genera of Gram positive oral bacteria.

Answer 1

• 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)

Question 2

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

Answer 2

• Coagulase negative staphylococci

- Staphylococci

Question 3

what do oral staph pose a risk for?

Answer 3

oral disease and cross contamination

Question 4

how sensitive is staphylococci species to methicillin?

Answer 4

90%

Question 5

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

Answer 5

lactobacilli

Question 6

What is the shape of lactobacillus’s rods?

Answer 6

pleomorphic

Question 7

why are lactobacilli described as acidogenic and acidic?

Answer 7

survive and reproduce under acid conditions .. pH 5.5

Question 8

how adhesive is lactobacilli?

Answer 8

poor adhesion properties so late colonisers (EPS important)

Question 9

Name the 3 main groups of lactobacilli.

Answer 9

• Homolactic fermenters (>65%)
• Heterolactic fermenters
• Facultative heterolactic fermenters

Question 10

Describe homolactic fermenters.

Answer 10

– produce only lactic acid from sugar

– Embden-Meyerhof pathway of glycolysis

Question 11

Describe heterlactic fermenters.

Answer 11

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

Question 12

Describe facultative heterolactic fermenters.

Answer 12

– normally homolactic fermenters

– can switch to heterolactic fermentation (induce)

Question 13

what is the most damaging product of pyruvate?

Answer 13

lactic acid

Question 14

Name common lactobacillus species.

Answer 14

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

Question 15

what do lactobacillus species compete with?

Answer 15

mutans

Question 16

what is dentine caries associated with?

Answer 16

deep carious lesions (low pH environment)

Question 17

what do levels of lactobacilli in salvia correlate with?

Answer 17

carbohydrate intake

Question 18

what are dentine caries test used for?

Answer 18

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

Question 19

what happens to lactobacilli as mutans sterptococci falls?

Answer 19

tend to increase

Question 20

where are high numbers of lactobacilli found?

Answer 20

carious dentine

Question 21

what is there is a positive correlation between?

Answer 21

numbers of lactobacilli and carious lesions

Question 22

what role does lactobacilli have in initiating dimineralization?

Answer 22

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

Question 23

what are caries susceptibility tests used to determine?

Answer 23

Determine the numbers of cariogenic bacteria in saliva

S. mutans & Lactobacilli

Question 24

what is targeted on high risk patients?

Answer 24

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

Question 25

How can lactobacilli be protective?

Answer 25

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

Question 26

what are actinocymes?

Answer 26

Gram +ve pleomorphic rods

Question 27

what is actinomyces a major proportion of?

Answer 27

microflora

Question 28

how is actinomyces arranged?

Answer 28

singly, in pairs, short chains or clumps

Question 29

does actinomyces form pores?

Answer 29

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

Question 30

what are other features of actinomyces ?

Answer 30

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

Question 31

Where is actinomyces mainly found?

Answer 31

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

Question 32

Name 2 actinomyces in the mouth.

Answer 32

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

Question 33

what historically is actinomyces associated with?

Answer 33

root surface caries

Question 34

Describe actinomyces naeslundi.

Answer 34

• 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

Question 35

Describe Actinomyces israelii.

Answer 35

• 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

Question 36

What is thick fluid expressed from the sinuses known as?

Answer 36

sulphur granules ( yellow, granular ,particulate)

Question 37

what are granules in pus?

Answer 37

pathogenic (indicator of disease)

Question 38

Pus is aggregations of what?

Answer 38

actinomyces filaments

Question 39

What is in >80 % of all actinomyces lesions?

Answer 39

A. Israelii

Question 40

What is the treatment for actinomyces lesions?

Answer 40

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)

Question 41

describe features of eubacterium species.

Answer 41

•  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

Question 42

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

Answer 42

• Propionibacterium
• Rothia
• Corynebacterium

Question 43

Describe Propionibacterium propionicus.

Answer 43

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

Question 44

Describe Propionibacterium acnes.

Answer 44

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

Question 45

Describe rothia dentocariosa.

Answer 45

• 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

Question 46

Describe corynebacterium matruchotii.

Answer 46

– 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

Question 47

Describe distribution of key species in plaque.

Answer 47

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