Staphlocci and streptococci Flashcards
How do staphs appear?
They appear as clumps
“Like a bunch of grapes”
Name three important strains of staph?
S. aureus
S. haemolyticus
s. saprophyticus
Where do you get s. aureus from?
boils, impetigo, sepsis
where do you get s. haemolyticus from?
infected IV lines and catheters
Where do you get saprophyticus from?
UTIs
What is the most common classification system for staphs?
kloos and schleifer system
what is the kloos and schleifer system?
the most common classifcation system for staphs
what can the kloos and schleifer system do?
name 30+ strains by name
concerned predominantly with animal strains
Where can staphs grow?
on a wide range of media
how do staphs appear on media?
as white creamy colonies (depending on species)
what are the two main catagories of staphs
coagulase positive and coagulase negative
give an example of coagulase positive staph?
s.aureus.
what % does s. aureus colonize?
40% of the noses of the population and 70% of the noses of hospital populations
which staphs are coagulase negative?
the vast majority
what do coagulase negative staphs colonize?
man and animal skin. They are usually species specific.
Name a way to distinguish between s. aureus and CNS, besides coagulase test.
DNAase production, as only aureus is positive
what do staphs cause?
diseases from food poisoning to life threatening infections such as septicaemia.
what are the most common organisms in hospital infections?
staphs
Name 12 enzymes and other virulence factors of staphs LPD CCC BC FC SSH
Lipase, phosphatidylinositol, DNAase, Capsule, Catalase, Coagulase, bound coagulase, free coagulase, Staphlokinase, Staph A protein, Hyaluronidase.
What does Lipase do for staphs?
Degrades lipids, it is important in boil formation.
What does phosphatidylinositol-Specific phosopholipase C do for staphs?
It makes tissues susceptible to activated complement
What does DNAase do for staphs?
It degrades DNA
What does hyaluronidase do for staphs?
It breaks down interstitial hyaluronic acid. it is a spreading factor.
What does coagulase do for staphs?
It has a thrombin-like activty. It inhibits phagocytosis by coating cocci and PMNs with fibrin.
What does bound coagulase do for staphs?
It is a ‘clumping factor’. It is attached to cell walls. It has a direct action on fibrinogen.
What does free coagulase do for staphs?
It is secreted and interacts with coagulase reacting factor to form a ‘thrombin-like complex’
what does staphlokinase do for staphs?
Fabrinolytic, it converts plaminogen to plasmin, causing clot lysis.
What does catalase do for staphs?
it breaks down h2o2, and preserves microbe viability.
what does teichoic acid do for staphs?
It aids in adherance and colonization.
What does the capsule do for staphs?
It inhibits phagocytosis & promotes adherence.
What does staph A protein do for staphs?
It is a structure component that inhibits opsonisation by absorption of IgG. It causes the activation of complement, triggering an allergic reaction.
