Gram-Positive Agent Characteristics Flashcards
What five classes/antibiotics demonstrate concentration-dependent bactericidal activity?
Aminoglycosides, daptomycin, fluoroquinolones, metronidazole, lipoglycopeptides
What are the four resistance mechanisms found in streptococcus pneumoniae and what antibiotics are affected?
Changes in PBP: beta-lactam antibiotics (except ceftriaxone, cefotaxime)
ermB gene: changes in ribosome (clindamycin + macrocodes)
gyrase change: fluoroquinolone
Efflux (mefA): macrolide resistance only
What major drug interaction is observed with Quinupristin/dalfopristin?
CYP 3A4 inhibitor
What major drug interaction is observed with the oxazoledinones (linezolid/tedezolid)?
MAO inhibitor – risk of serotonin syndrome and pressor response
What is the major drug interaction with daptomycin?
Statins – may synergistically increase risk of myopathy
What two drugs have a drug-lab interaction and what is that interaction?
Telavancin and oritavancin; coagulation tests PT, aPTT, INR
What agents (exam 1) have activity versus anaerobes?
piperacillin, Zosyn, Unasyn, Augmentin, Timentin, cefoxitin, cefotetan, carbapenems, and vancomycin (gram-positive)
What are the major adverse effects of vancomycin?
nephrotoxicity, ototoxicity, red man syndrome, interstitial nephritis, and thrombophlebitis
What are the risk factors for nephrotoxicity with vancomycin?
Renal insufficiency, prolonged therapy, high dose, high trough level, concurrent use of other nephrotoxic agents
What are the primary adverse effects associated with Synercid?
myalgia, arthralgia, venous irritation
What are the primary adverse effects associated with linezolid/tedezolid?
Optic and peripheral neuropathy, thrombocytopenia (don’t start if plt <50), anemia
What are the primary adverse effects associated with daptomycin?
Acute eosinophilic pneumonia, myopathy with CPK elevation
What are the primary adverse effects associated with telavancin?
QTc prolongation, taste disturbance, nephrotoxicity, red man syndrome (only one shared with other lipoglycopeptides)
According to Erdman, what is the PKPD characteristic that predicts efficacy for linezolid?
T > MIC, bacteriostatic
What two antibiotics cover VRSA?
Daptomycin, linezolid
What VRE-targeting antibiotic only covers E. faecium and not E. faecalis?
Synercid
What agents cover PRSP (so far)?
Ceftriaxone, cefotaxime, cefepime, ceftaroline, vancomycin, linezolid, daptomycin, synercid, lipoglycopeptides
What agents cover MRSA (so far)?
Ceftaroline, vancomycin, synercid, linezolid, daptomycin, lipoglycopeptides
What agents cover VRE?
Synercid (if faecium), linezolid, daptomycin, oritavancin, and telavancin/dalbavancin (only against some b/c same MOR)
What agents (so far) cover pseudomonas?
Penicillin: Ticarcillin, piperacillin, Timentin, Zosyn
Ceph: ceftazidime, cefoperazone, combo with BL
Carbapenem: all except ertapenem
Aztreonam
What gram-positive agents can penetrate into the CSF?
Vancomycin variable, linezolid 30%
What gram-positive agents must be adjusted in renal insufficiency?
vancomycin, daptomycin, dalbavancin, telavancin
What gram-positive agents are removed by hemodialysis?
if new dialyzer, vancomycin can be removed a small amount (30%).
Linezolid/tedezolid are removed
What drugs can demonstrate cross-resistance with vancomycin?
Telavancin and dalbavancin – also inhibited when D-Ala-D-Ala changes to D-Ala-D-Lac. Oritavancin is not.
What is the mechanism of resistance behind VISA?
Thickening of the staph aureus cell wall. increases the MIC to vancomycin.
What gram-positive antibiotic inhibits the formation of the ribosomal 70S complex?
Linezolid/tedezolid
What gram-positive antibiotic aggregates in the cell walls of bacteria, poking holes in the wall?
Daptomycin
Is Synercid bacteriostatic or bacteriocidal?
By using quinupristin/dalfopristin together, Synercid can be bactericidal (per Cushman) for some organisms (per Erdman)
What are the only gram-positive targeting abx that are available orally?
Linezolid/tedezolid
oral vancomycin for c. diff
What are the only differences between linezolid and tedezolid?
Tedezolid has greater potency against MRSA and has once daily dosing. Otherwise, less evidence base.
