Gram Positive Bacteria (Staphylococcus) Flashcards
Staphylococcus Aureus can cause…
Food poisoning, bone infections, endocarditis, bacteraemia and skin/soft tissue infections.
Staphylococcus Aureus 3 infections
Scaled skin syndrome, toxic syndrome, MRSA.
Scalded skin syndrome
Toxin production causes skin layers to shed.
Rarely life threatening < 3% mortality.
Treat with oral antibiotics.
Toxic shock syndrome
Fever, hypotension, rash.
Involves multiple organ systems.
Desquamation of the skin on soles/palms.
MRSA is most common in…
Elderly, catheters, surgical wounds and ICU.
MRSA treatment is
Vancomycin
Staphylococcus epidermis
Lives on skin, infection risk with cannulae, longlines and pacemakers.
How often do you change a cannulae
At least every 72 hours.
% of MRSA that is now resistant?
80-90%
Why is MRSA resistant to penicillin?
It produces penicillinase AKA B-lactamase enzyme.
B-lactamase enzyme does what?
It destroys certain B-lactams.
What is used to kill S.Aureus that makes penicillinase?
Flucloxacillin (oral/iv)
Why does Flucloxacillin not kill all S.Aureus that make penecillinase?
Because some S.Aureus are now resistant to penicillinase stable B-lactams (e.g fluclox and methicillin)
Why is MRSA resistant to B-lactam abx?
Because S.aureus acquired new PBP (PBP2) encoded by gene mecA.
PBP2A has…
A low affinity for B-lactam abx, is not blocked by them, so carries on building cell wall.
