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
- peptidoglycans
- 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
- rifampin
- Which are the bacteriacidal Abx
- Penicillin, cephalosporin, vancomycin, aminoglycosides, fluoroquinolones, metronidazole
- These drugs disrupt the bacterial/fungal cell membranes
- polymyxins
- 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
- TRUE
- 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
- TRUE
- 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.