M9- Gram postive oral bacteria Flashcards
Name the major genera of Gram positive oral bacteria.
- 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)
What does CNS stand for and what bacteria is it associated with?
- Coagulase negative staphylococci
- Staphylococci
what do oral staph pose a risk for?
oral disease and cross contamination
how sensitive is staphylococci species to methicillin?
90%
After streptococci , what is the next most important group of bacteria involved in dental caries?
lactobacilli
What is the shape of lactobacillus’s rods?
pleomorphic
why are lactobacilli described as acidogenic and acidic?
survive and reproduce under acid conditions .. pH 5.5
how adhesive is lactobacilli?
poor adhesion properties so late colonisers (EPS important)
Name the 3 main groups of lactobacilli.
- Homolactic fermenters (>65%)
- Heterolactic fermenters
- Facultative heterolactic fermenters
Describe homolactic fermenters.
– produce only lactic acid from sugar
– Embden-Meyerhof pathway of glycolysis
Describe heterlactic fermenters.
– equal amounts of lactic acid, acetic acid (or ethanol) & CO2
Describe facultative heterolactic fermenters.
– normally homolactic fermenters
– can switch to heterolactic fermentation (induce)
what is the most damaging product of pyruvate?
lactic acid
Name common lactobacillus species.
- lactobacillus casei Gp (most common) (homofermenter)
- lactobacillus acidophilus (homofermenter)
- lactobacillus fermentum (heterofermenter)
what do lactobacillus species compete with?
mutans
what is dentine caries associated with?
deep carious lesions (low pH environment)
what do levels of lactobacilli in salvia correlate with?
carbohydrate intake
what are dentine caries test used for?
to follow patients over time &/or in combination with other caries predictive tests
what happens to lactobacilli as mutans sterptococci falls?
tend to increase
where are high numbers of lactobacilli found?
carious dentine
what is there is a positive correlation between?
numbers of lactobacilli and carious lesions
what role does lactobacilli have in initiating dimineralization?
No major role in initiating demineralization, important in progression once low pH established
what are caries susceptibility tests used to determine?
Determine the numbers of cariogenic bacteria in saliva
S. mutans & Lactobacilli
what is targeted on high risk patients?
preventive measures (dietary advice, fissure sealants, fluoride varnishes etc.)
How can lactobacilli be protective?
• L. rhamnosus milk protected pre-school children
• L. casei & L. rhamnosus reduced S. mutans
colonisation
what are actinocymes?
Gram +ve pleomorphic rods
what is actinomyces a major proportion of?
microflora
how is actinomyces arranged?
singly, in pairs, short chains or clumps
does actinomyces form pores?
can grow as branched network of hyphae but do not form spores
what are other features of actinomyces ?
– anerobic or facultative anaerobes (CO2 for Optimal Growth)
– Some possess fimbriae which aid in adherence and aggregation
– non motile
Where is actinomyces mainly found?
in the mouth, in dental plaque, in tonsil crypts (some in the female genital tract)
Name 2 actinomyces in the mouth.
– A.naesludii
– A.odontolyticus
(Found in supra & subgingival plaque)
what historically is actinomyces associated with?
root surface caries
Describe actinomyces naeslundi.
• 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
Describe Actinomyces israelii.
• 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
What is thick fluid expressed from the sinuses known as?
sulphur granules ( yellow, granular ,particulate)
what are granules in pus?
pathogenic (indicator of disease)
Pus is aggregations of what?
actinomyces filaments
What is in >80 % of all actinomyces lesions?
A. Israelii
What is the treatment for actinomyces lesions?
- Removal of original dental focus of infection
- incision and drainage of lesion
- long term antibiotic treatment:
penicillin/amoxycillin (up to 6 weeks)
describe features of eubacterium species.
• 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
what other gram + genera are found in the mouth and in dental plaque?
- Propionibacterium
- Rothia
- Corynebacterium
Describe Propionibacterium propionicus.
– produces propionic acid as the major fermentation product
– mouth, dental plaque and calculus
– Similar to Actinomyces israelii
• causes actinomycosis-type lesions & tear duct infections
Describe Propionibacterium acnes.
– inhabits the skin, acne lesions and soft tissue abscesses.
– Found in periodontal pockets in association with periodontal disease
Describe rothia dentocariosa.
- 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
Describe corynebacterium matruchotii.
– 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
Describe distribution of key species in plaque.
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
