Virulence factors
activates fibrinogen to fibrin → fibrin clot
Coagulase
provide a description including gram stain, shape, catalase +/-
Gram positive cocci (pairs and chains), catalase negative
this is released by SA to sense quorum
agrD (which then becomes AIP)
binds to d-ala-d-ala portion of the peptidoglycan wall
vancomycin
Blood culture positive for Staph aureus and ultrasound shows tricuspid regurgitation
Yes
binds Fc portion of IgG → protection from humoral response and phagocytosis
Protein A
optochin sensitivity?
resistant
Most likely organism for prosthetic valve endocarditis?
Staphylococcus epidermidis
Gram +, Catalase positive, coagulase negative, novobiocin sensitive
AgrA is a transcription factor for ___, which leads to increased biofilm production
RNA Pol III
Patient is an IV drug user, presents with fever of 101, nodules on soles of foot, red spots on retinal fundus, ECHO is normal, urine shows trace blood
Y because has 5 minor despite normal echo
Non-specific binding of MHC II and TCRs on CD4 T cells Promotes excess cytokines released (e.g., IL-1, TNF)
TSST-1
T/F this can affect only a valve that has already been damaged.
True
SCCmec IV has more or less antibiotic resistance than SCCmec II?
Less but has more virulence factors (CA)
By what mechanism of resistance is MRSA resistant to methicillin?
Changed PBP2 to PBP2A so modification of target
Blood culture shows staph aureus, the patient has a temp of 100, fundus photo shows red spots, patient former user of IV drugs.
N, only 1 major and 2 minor are met. Temp is not high enough, needs to be >100.4
present in community acquired SA and aka "leukocydin" because punches holes in WBC's.
PVL
uses this to facilitate binding fibrin-platelet aggregates on damaged heart valves
dextrans
holosystolic murmur; loudest at the left sternal border
tricuspid valve regurg. mitral valve regurg would be loudest at the apex
Toxin present in community acquired SA and involved in biofilm formation and immune cell dysregulation
Phenol-soluble toxins
activates plasminogen to plasmin to digest fibrin clots → dissemination
staphylokinase