M9 - Gram + Flashcards
list 3 major genera f Gm +ve oral bacteria
- Actinomyces spp.
- lactobacillus spp.
- eubcterium spp.
after streptococci which bacteria are the most important group of bacteria involved in dental caries?
lactobacilli
what shape are lactobacilli?
pleomorphic rods
facultative anaerobe
what features do lactobacili have?
Acidogenic and aciduric
-survive and reproduce under acidic conditions pH 5.5
what are the 3 main groups of lactobacilli?
- homolactic fermenters
- heterolactic fermenters
- facultative heterolactic fermenters
what do homolactic fermenters produce?
- produce only lactic acid from sugar (glucose)
name some lactobacillus species (homofermenter)
- L casei Gp
- L rhamnosus
- L paracasei
- L acidophilus
what is the link between lactobacilli and carbohydrates?
level of lactobacilli in saliva correlates with carbohydrate intake
- associated with deep carious lesions
as streptococci tend to fall what happens to the lactobacilli?
tend to increase
lactobacilli have no major role in initiating demineralisation, important in progression once low pH established
true
what is the count of lactobacillus in HIGH predicted caries activity?
10000+ per ml of saliva
which lactobacilli have protective measures?
- L. rhamnosus milk protected pre-school children
- Lcasei and L. rhamnosus reduced S.mutans colonisation
Actinomyces are gram +ve pleomorphic rods
true
features of actinomyces
Major proportion of microflora
- aneraobic or facultative anaerobes
- some possess fimbriae which aid in adherence and aggregation
where are actinomyces mainly found?
mainly found in the mouth in dental plaque, in tonsils crypts
name two different species of Actinomyces in the mouth
- A.naesludii
- A- odontolyticus
found in supra and subgingival plaque
what are actinomyces historically associated with?
- root surface caries
what is the effect of actinomyces naeslundii?
- produce extracellular slime and fructans from sucrose
- found in large numbers in dental plaque
- able to cause periodontal disease when introduced in hamsters
describe actinomyces israelii
- opportunistic and most likely to cause actinomycosis
what are the characteristics of pus?
thick fluid expressed from the sinuses
- known as sulphur granules
- aggregations of actinomyces filaments
what is the treatment of actinomycis
long term antibiotic treatment up to 6 weeks
propionibacteria is a gram + bacteria what does it produce?
propionic acid as the major fermentation product
