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antimicrobials 4-15-06


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The penicillin type drugs work by blocking ------ synthesis, specifically by inhibiting this molecule from cross-linking?
blocks bacterial cell wall synthesis by inhibition of peptidoglycan synthesis.
Which other drugs (aside from penicillins)block peptidoglycan cross linking?
Imipenem, aztreonam and cephalosporins
Bacitracin, vancomycin and cycloserine block the synthesis of this molecule, preventing cell wall synthesis
These drugs block the 50s ribosomal subunit
chloramphenicol, erythromycin, cLindomycin, Lincomycin, streptogramins "Buy AT 30, CELL at 50"
These drugs block the 30s ribosomal subunit
Aminoglycosides and tetracyclines "Buy AT 30, CELL at 50"
These drugs block nucleotide synthesis by interfering with the folate pathway
Sulfonamides (e.g. Bactrim), trimethoprim
These drugs block DNA topoisomerases
Quinolones (e.g. Cipro)
Which drug blocks mRNA synthesis
Which are the bacteriacidal Abx
Penicillin, cephalosporin, vancomycin, aminoglycosides, fluoroquinolones, metronidazole
These drugs disrupt the bacterial/fungal cell membranes
These specific disrupt fungal cell membranes
fluconazole/azoles, amphotericin B, nystatin (FAN the fungal cell membranes)
What is the mechanism of action of Pentamidine
Unknown (tx for pneumocistis and sleeping sickness--leishmania)
Penicillin Which is the IV form and which is the oral form
G = IV, V=oral
Which of these is not a mechanism of penicillin action: (1) binds penicillin-binding protein, (2) blocks peptidoglycan synthesis, (3) blocks transpeptidase catalyzed cross-linking of cell wall and (4) activates autolytic enzymes
Penicillin does not block peptioglycan synthesis, bacitracin, vancomycin and cycloserine do that
T or F: penicillin is effective against gram pos and gram neg rods
False: penicillin is used to treat common streptococci (but not staph), meningococci, gram pos bacilli and spirochetes (i.e. syphilis, treponema). Not used to treat gram neg rods.
What should you watch out for when giving penicillin?
Hypersensitivity rxn (urticaria,severe pruritus) and hemolytic anemia
Methicillin, nafcillin, dicloxacillin These drugs are used mainly for what type of infection
Staphlococcal infection (hence very narrow spectrum)
Methicillin, nafcillin, dicloxacillin T or F: these drugs have the same mechanism of action as penicillin
Methicillin, nafcillin, dicloxacillin Are these drugs penicillinase resistant? If so why?
Bulkier R group makes these drugs resistant to penicillinase
Methicillin, nafcillin, dicloxacillin What should you watch out for when giving these drugs?
Hypersensitivity rxn (urticaria,severe pruritus); methicillin can cuase interstitial nephritis
Ampicillin and amoxicillin T or F: these drugs have the same mechanism of action as penicillin
Ampicillin and amoxicillin Which has greater oral bioavailability?
amOxicillin (O for Oral)
Ampicillin and amoxicillin What do you use these for?
Ampicillin/amoxicillin HELPS to kill enterococci (H. influenzae, E. coli, Listeria monocytogenes, Proteus mirabilis, Salmonella, enterococci)
Ampicillin and amoxicillin Can penicillinase effect these drugs efficacy?
Yes, they are penicillinase sensitive
Ampicillin and amoxicillin Why not give these drugs with a penicillinase inhibitor. Name one.
clavulanic acid
Ampicillin and amoxicillin What should you watch out for when giving these drugs?
Hypersensitivity rxn (ampicillin rash), pseudomembranous colitis
ticarcillin, carbenicillin, piperacillin Why are these considered to have an extended spectrum?
Because they are effective against pseudomonas and other gram neg rods (enterobacter and some species of klebsiella) TCP: Takes Care of Pseudomonas
Carbenicillin, piperacillin, ticarcillin What should you watch out for when giving these drugs?
Hypersensitivity rxn
Carbenicillin, piperacillin, ticarcillin: why administer with clavulanic acid ?
Because they are penicillinase sensitive.
Cephalosporins What is the mechanism of action of Cephalosporins?
inhibit cell wall synthesis
Cephalosporins How are they similar/different from penicillin?
both have a beta-lactam ring structure but cephalosporins are less susceptible to penicillinases
Cephalosporins What are the main similarities/difference between 1st and 2nd generation cephalosporins?
2nd gen has extensive gram neg coverage but weaker gram pos coverage
Cephalosporins 1st gen covers what bugs?
gram positives (staph and strep), Proteus mirabilis, E. coli, Klebsiella (PEcK)
Cephalosporins 2nd gen covers what bugs?
gram positives (staph and strep) though less so, H. influenzae, Enterobacter aerogenes, Neisseria, Proteus mirabilis, E. coli, Klebsiella (HEN PEcK)
Cephalosporins What can 3rd generation drugs do that 1st and 2nd generation can't?
Cross the blood brain barrier
Cephalosporins What are some other benefits of 3rd gen?
better activity against gram neg bugs resistant to beta-lactam drugs. Ceftazidime for Pseudomonas and ceftriaxone for N. gonorrhea
Cephalosporins What are the benefits of 4th gen? name a couple
(cefepime, cefpiramide) inc activity against pseudomonas and gram positives
Cephalosporins What drugs should you avoid taking with cephalosporins?
Aminoglycosides (increases nephrotoxicity) and ethanol (causes a disulfiram-like rxn -- headache, nausea, flushing, hypotension)
Aztreonam When would you use aztreonam?
Only to treat Klebsiella, Pseudomonas and Serratia spp.
Aztreonam Is it beta-lactamase resistant?
Yes, this is one of the huge benefits of the drug, and it is not cross-reactive with PCN!
Aztreonam Which population of pt. is this drug good for?
The PCN-allergic patient that can't take aminoglycosides b/c of renal insufficiency
Aztreonam Are there any toxicity issues with this drug?
Not really. Generally well tolerated with occasional GI upset. Vertigo, Headache and rare hepatotoxicity have been reported.

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