Antibiotics Effective Against MRSA and VRE Flashcards
What occurs in MRSA?
Organism acquires resistance via another mechanism besides production of beta-lactamase. By altering its PCN binding protein, the protein which beta-lactams bind to, these medications to have no effect on this type of S. Aureus.
MRSA is a Gram ___ bacteria.
+
Which is the only beta-lactam that MRSA is not resistant to?
Ceftaroline
How is infection vs colonization of MRSA treated?
Infection: treat
Colonization: isolation
Which drugs are usually used to treat S. Aureus and why?
Methicillin, oxacillin, dicloxicillin, nafcillin
They are beta-lactamase resistant organisms
VRE can be either entercoccus faecium and/or faecalis and are both Gram _____ .
+
Faecalis is more common but not always vanco resistant
Faecium more likely to be resistant
What is the mainstay treatment of MRSA and enterococcus?
Vancomycin
not susceptible to beta-lactamase and binds to a different site than other PCN making is effective against MRSA
What is vancomycin’s MOA?
Inhibits cell wall synthesis
Is vancomycin bacteriostatic or bacteriocidal?
Cidal
How is vanco administered and why?
Large glycopeptide that has poor oral absorption so is primarily used IV
When would vanco be given PO?
C.diff d/t its local antibacterial effects
Vancomycin’s spectrum of action is against Gram ____ and what organisms?
+
MRSA, STACN, S. pneumoniae including pen-R
AE of vancomycin include:
Ototoxicity
Nephrotoxicity
Hypersensitivity
Red Man’s syndrome
How can Red Man’s Syndrome d/t vancomycin infusion be controlled?
Slow infusion rate
premedicate with antihistamine
(not an allergy)
How is vanco cleared from the body?
Renally
What are some instances when you would check a vanco trough?
- Anticipated IV therapy for >4days (mod/severe inf)
- Unstable renal function
- Burns, morbidly obese, significant edema, cystic fibrosis
- Pts on other nephrotoxic drugs (amphotericin B, aminoglycosides, cyclosporin)
- Dialysis
- Poor clinical response to vanco
What type of vanco level should be obtained in patients undergoing dialysis?
Random
Why do we check troughs in patients taking vancomycin?
Vanco exhibits time dependent killing
Troughs are checked to see if the dose is above MIC or high enough. If the trough is within normal limits this means the patient had a high enough concentration for the entire dosing interval and therefore a high enough dose.
When might a peak be recommended in patients taking vanco?
To confirm high serum concentrations to ensure adequate penetration into certain sites of infection (osteomyelitis, endocarditis, CNS infections)
**generally not required
When is a vanco trough typically drawn and why?
30mins prior to the 3rd dose so that the drug has time to reach a steady state (if drawn during redistribution phase, may get a falsely high level)
What is the suggested goal trough level of vanco?
Most inf: 5-15mcg/mL
CNS inf, MRSA HAP/VAP: 15-20mcg/mL
What type of Streptogramin is used to treat MRSA and VRE (E. faecium) and what is its MOA, static/cidal, route of administration?
Synercid (Quinupristin/dalfopristin)
MOA: Inhibition of protein synthesis via action of 50S subunit
Cidal
IV
AE and DI of Synercid:
AE: Infusion site effects, arthralgias, myalgias, increased transaminases
DI: Inhibition of CYP3A4
Which drug used to treat VRE and MRSA acts to inhibit protein synthesis via inhibition of the 70S ribosomal initiation complex?
Linezolid
