7.3 MRSA Flashcards
(20 cards)
MRSA group of gram __ bacterial strains
positive
colonzies..
skin and nasal areas
can infect through..
skin abrasions, abscesses, burns, surgical sies.
generally a limited cause of..
pneumonia
MRSA highly resistanct to
the methicillin class of antimicrobials
what type of acquired MRSA is a major issue
community acquired MRSA
community acquire MRSA major issue for who
individuals in close contact – sports, prisons,
antimicrobial resistance of MRSA
strong resistance to B lactams, SCCmec cassetes
SCCmec caries..
mecA gene that encodes PBP2a
PBP2a
very low affinity for B lactam antibiotics meaning these drugs cannot bind to stop cell wall syntehsis
penicillin binding protein – protein that binds to penicillin an dmakes it incapable of bloicking cell wall synthesis
MRSA is slowly gaining resistance to
vancomycin – VISA and VRSA strains appearing
VRSA srrains
resistant to vancomycin completely
VISA strains
intermediate – means still sensitive to increased levels of vancomycin
what is an alternative drug beyond vancomycin
linezolid – but very expensive and toxic to mitochondria
mechanisms leading to infection and disease - capsule
capsule displays anti-phagocytic action
– prevents phagocytosis by neutrophils
- even if neutrophils have been able to engulf MRSA, the strains are known to survive within them (hijacking neutrophils)
S. aureus has surface associated proteins and toxins that promote adhesion and damage tissues – what is an example of a protein
sortase
sortase
mediates anchoring to the cell wall
bacterial proteins of sortase
protein A and clumping factor (ClfA)
Protein A - when its bound to cell wall
when bound to bacterial cell wall, the bacteria can bind to the antibodies in host cell and now antibodies cannot act on other features of bacterium (hijacked antibodies)
clumping factor ClfA
attached to peptidoglycan, can act as anchor and bind to fibronectin - allows colonization of host cell
