Staphylococci Flashcards
Which body parts can be infected by Staphs?
URT, skin, genital tract, udder
Which species trasmit MRSA to people?
Horses and dogs
Why do you see clumps and clusters in smears of pus?
Divide in many planes
What is capsulation like?
Not capsulated in vitro, but clinical isolates often are
What are the capsules made of?
Polysaccharide and hyaluronic acid
What do MSACRAMMs do?
Bind to specific extracellular matrix epithelium
What do adhesins mimic?
Host molecules
Where are MSCRAMMs anchored?
Peptidoglycan of the cell wall
What molecules can MSCRAMMs be?
Polysaccharides such as poly-n-succinyl glucosamine OR proteins with the LPXTG motif such as fibronectin-binding protein, collagen binding protein or clumping factor which binds fibrinogen
What does protein A do?
Fixes complement and binds IgG to prevent opsonisation
What does coagulase do?
Binds plasma proteins and inhibits complement
How do Staphs inhibit phagocytes?
Peptidoglycans which inhibit chemotaxis and directly inhibit phagocytosis
Which haemolysins do Staphs produce?
Beta (phospholipase C)
Which kind of lysis do Staphs show?
Hot-cold (complete lysis if cold)
Why is secreted coagulase important?
Coagulates PPs, inhibits complement lysis and opsonisation, causes platelet clumping
What is coagulase and catalase activity of most pathogenic Staphs like?
Positive
Which exotoxins cause necrosis of phagocytes?
Alphatoxin and leucocidin
Which exotoxin is a plasminogen activator?
Stapylokinase
What are the properties of a Staph colony?
Facultatively anaerobic, medium sized, yellow
How else can you identify a Staph species?
Sugar fermentation (API strips)
In which body parts are staphs commensal?
URT, skin, vulva, vagina, sheath, udder
How are staphs transmitted?
Animal to animal or mechanical transfer
Where is beta lactamase encoded?
On the plasmid, so use non beta-lactam or clavulanic acid
