Gram-positive bacteria Flashcards
(23 cards)
give examples of 6 gram + bacteria?
- staphylococcus aureus
- streptococcus pyogenes
- streptococcus mutans
- lactobacilli
- actinomycetes
- streptococcus sanguinis
what is the difference between gram + and gram - bacteria?
Gram + = thick peptidoglycan layer and plasma membrane
Gram - = Thin peptidoglycan layer and plasma membrane with lipopolysaccharides
what do lipopolysaccharides do in gram - bacteria?
provide bacterial/antigen toxicity
give some facts about staphylococcus aureus?
- adaptable bacteria
- 20% of population constantly colonised (not always a bad thing)
- MRSA (methicillin resistant staph aureus)
- associated with abscess, impetigo, scaleded skin syndrome and forgein bodies
what is streptococcus pyogenes?
gram + bacteria that causes 15% of sore throats
it can give scarlet fever where tongue goes red/raw/prominent papilla
it gives skin infections eg necrotizinf facitits, cellulitis, impetigo
what does streptococcus mutans cause?
LEADING CAUSE OF DENTAL CARIES
what makes streptococcus mutans so effective?
it has a broad spectrum of carbohydrates as an energy source
what conditions does streptococcus mutans thrive in and what is this called?
acidic conditions - aciduric bacteria
where is streptococcus mutans most commonly found?
in dental fissures
how does streptococcus mutans cause dental caries?
- binds and colonises to the tooth surface
- produces a sticky extracellular polysaccharide (helping it stay on the tooth)
- produces acid at a quick rate (pH 4)
- tolerates high acidic conditions
where is streptococcus oralis mitis found and what is the serious relevance of it?
in the mouth, if this bacteria enters the bloodstream it can cause bacterial endocarditis (inflammation of the heart membrane)
what is the role of streptococcus oralis mitis in the formation of a plaque biofilm?
acts as a tether for other bacteria to attach to which helps kick of the biofilm
define a facultitive anaerobe
can metabolise with or without O2 (not resitricted to set conditions unlike obligate anaerobes)
what is the name of the 2nd more relevant bacteria in the formation of dental caries?
lactobacilli
in which carious lesions is lactobacilli found?
deep carious lesions
what type of anaerobe is lactobacilli
facultative anaerobe
whar does lactobacilli look like under a microscope?
pleomorphic rods (vary in shape)
what are 2 properties of lactobacilli?
- aciduric (withstands acidic conditions)
- acidogenic ( produces acid )
the level of lactobacilli correlates to the diet in what way?
more lactobacilli to more carbohydrate intake
actinomyces is historically associated with what type of caries?
root surface caries
where is actinomyces usually found?
in both supra and subgingival plaque
what does actinomyces look like under a microscope?
pleomorphic rods (that vary in shape)
what can actinomyces be?
- aerobic
OR - facultative
