Antimicrobial 2

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  1. Are penicillins static or cidal?
  2. What is the mechanism of action of penicillins?
    interfere with bacterial cell wall formation
  3. Are penicillins most effective against actively growing and dividing bacteria, or against non-reproducing bacteria?
    against actively growing and dividing bacteria
  4. Should penicillins be used with static antimicrobial drugs? Why or why not?
    no-because static drugs prevent bacteria from actively growing and dividing (reproducing), so the penicillins do not get a chance to interfere with the bacterial cell wall formation
  5. In general, most penicillins should be given on an empty stomach. Which one can be given with food?
  6. How are penicillins excreted?
    mostly by the kidney, into the urine
  7. Can penicillins reach high concentrations in the urine? Why?
    yes-because penicillins are actively secreted by kidney tubule cells into the urine.
  8. What is a beta-lactam ring? What 2 main categories of antimicroial drugs have beta-lactam rings?
    a specific part of certain drug molecules - penicillins and cephalosporins.
  9. What is beta-lactamase?
    an enzyme secreted by certain strains of bacteria - some staphlylococci. Beta-lactamase breaks down the beta-lactam ring part of the penicillin or cephalosproin molecule, making the drug ineffective
  10. Who makes beta-lactamase - certain drugs, certain bacteria, or certain patients?
    certain bacteria - some staphylococci
  11. Who does beta-lactamase help - the drug, the bacteria, or the patient?
    the bacteria
  12. For our point of view, is beta-lactamase good or bad?
    bad - good for the bacteria, bad for the patient.
  13. What is penicillinase?
    a sub-category of beta-lactamase that specifically attacks the beta-lactam ring of penicillins.
  14. What is "cross-resistance"?
    If a particular strain of bacteria is resistant to a particular type of drug, it will probably be resistant to similar, related drugs.
  15. Are some bacteria naturally resistant to penicillins?
  16. Are some penicillins naturally resistant to beta-lactamase-secreting bacteria? Name 3 of them. Why are these particular drugs not used a lot?
    yes - oxacillin, dicloxacillin, cloxacillin. narrow spectrum
  17. Referring to antimicrobial drugs, waht does "portentiation" mean?
    a substance has been added to the drug to make it work better, give it a broader spectrum.
  18. What substance is commonly added to which penicillin to potentiate it? What is the proprietary name of this combination?
    clavulanic acid + amoxicillin = Clavamox
  19. Specifically, how does clavulanic acid potentiate the penicillin type drug?
    clavulanic acid binds tightly to beta-lactamase produced by bacteria, so the beta-lactamase cannot gt loose and attack the penicillin type drug
  20. How is Clavamox supplied - tablets loose in a bottle, or tables individually foiled wraped? Why?
    Individually foil wrapped. Because clavulanic acid absorbs moisture from the air, and tablets containing clavulanic acid will break down when exposed to air.
  21. In general, do penicillins work beter against Gram positive or Gram negative bacteria?
    gram positive
  22. Why are penicillins usually very safe for veterinary patients?
    Penicillins affect the cell walls of bacteria. Mammalian cells do not have cell walls.
  23. What are the 2 main precautions in penicillin use?
    anaphylactic reation, superinfection
  24. Are anaphylactic reactions more common in people or in pets?
  25. What is "superinfection"?
    When the antimicrobial drug kills off all of the normal gut flora, which allows pathogenic microorganisms to proliferate. This can cause severe, maybe fatal, diarrhea.
  26. If your doctor needs to prescribe an antimicrobial drug to an exotic animal, it is safe for her to pick out a penicillin type drug and just use the dog dosage for the exotic animal. True or false? Explain.
    False. We should use an exotic animal formulary when deciding what drugs and dosages to use in exotics. Penicillin type drugs can kill guinea pigs, ferrets, hamsters, and rabbits. Penicillins may be toxic in snakes, turtles, some birds,and chinchillas.
  27. Penicillins should never be used in livestock. True or false?
    False. Some penicillins are approved for use in livestock - be sure to observe withdrawal times.
  28. Most penicillins are well absorbed if given PO, with one exception. Name it, and tell why.
    Penicillin G - is inactivated by gastric acid
  29. Penicillin G is give parenterallly, and is often combined with what compounds to prolong its duration of action?
    procaine, benzathine
  30. Name 8 commonly used penicillins.
    penicillin - G, ampicilllin, amoxicillin, cloxacillin, dicloxacillin, oxacillin, carbenicillin, piperacillin
  31. Which is the most commonly used penicillin in small animal practice?
  32. What is amoxicillin often combined with to give it a broader spectrum of activity? What is this combination called?
    clavulanic acid. this combination is called Clavamox
  33. Are cephalosporins similar to the penicillins? Do they contain beta-lactam rings?
    yes and yes
  34. Are cephalosporins susceptible to beta-lactamase? Are the ccephalosporins as susceptible as the penicillins to beta-lactamase?
    yes. no.
  35. Are cephalosporins cidal or static? How do they work?
    cidal. like the penicillins, cephalosporins work on actively growing and dividing bacteria
  36. Briefly describe first generation cephalosporins. What type of bacteria do they affect? How are they administered? Give examples.
    first generation - oldest - mainly effect against Gram positive bacteria. some are given PO, some parenterally. "ceph" usuallly older. cefadroxil-Cefa-Tabs, cephalexin-Mefoxin
  37. Briefly describe third generation cepahlosporins. What type of bacteria do they affect? Give an example.
    third generation - newest - get even less Gram positive and even more Gram negative bacteria. most are injectable only. ceftiofur - Naxcel, cefpodoxime - Simplicef.
  38. How are cephalosporins excreted?
    liver and kidneys
  39. Can oral administration of cephalosporins cause suerinfection?
  40. Is bacitracin similar to penicillins?
  41. What route of administration is usually used or bacitracin?
  42. What 2 other antimicrobials are often combined with bacitracin for topical administration?
    neomycin, polymixin B
Card Set:
Antimicrobial 2
2012-02-12 16:37:49

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