21 - Antimicrobial Medications

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21 - Antimicrobial Medications
2010-06-10 16:39:47
Antimicrobial Medications

21 - Antimicrobial Medications
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  1. What is Salvarsan?
    • First documented chemical used as an antimicrobial.
    • Discovered by Paul Erlich in treatment of syphillis
  2. Who discovered penicillin and how?
    • Alexander Flemming
    • Accidentlly while working with staphyloccoccus.
    • Noticed there were no colonies growing near a mold contaminant...thought the colonies were "melting."
  3. When and what was the first antibiotic tested on humans?
    • WWII
    • Treatment of wounded soldiers for staphylococcus aureus infections
  4. What is Penicillin G?
    The first alteration of penicillin, broadened its spectrum
  5. What is MRSA?
    Methicillin Resistant Staphyloccocus Aureus
  6. Where do most modern antibiotics come from?
    Organisms living in the soil
  7. How are commerical antibiotics produced?
    • Strain inoculated into broth medium
    • Incubated until maximum ideal concetration is reached
    • Drug extracted from medium
    • Extensively purified

    Sometimes altered to achieve new characteristics, ie capsules, liquid.
  8. What is theapeutic index?
    • Lowest does toxic to patient divided by dose typically used for treatment.
    • High therapeutic index = less toxic to patient
  9. What are the 2 antimicrobial actions?
    • Bacteriostatic - inhibits further bacterial growth, but doesn't kill the bacteria
    • Bacteriocidal - kills bacteria
  10. What are the 2 spectrums of activity for antimicrobials?
    • Narrow Spectrum - Works on narrow range of organisms only. EX - Gram positive OR negative
    • Broad Spectrum - Works on broad range of organisms; causes disruption of normal flora
  11. What is a drugs half-life?
    • Time it takes for the body to eliminate one half the original dose in serum
    • Dictates frequency of dosage
  12. Synergistic, Antagonistic, and Additive effects of drugs on each other:
    • Synergistic - One drug enhances performance of another
    • Antagonistic - One drug interferes with effect of another
    • Additive - When added drug does not effect another drug
  13. What are the adverse effects of antimicrobial drugs?
    • Allergic Reactions - often life threatening
    • Toxic Effects - Aplastic anemia, body cannot make R or WBC's.
    • Supression of normal flora - When normal flora is diminished, other organisms have an opportunity to move in
    • Antimicrobial resistance - Microogranisms can come immune to antibiotics
  14. What are the "Mechanisms of Action" of antimicrobial drugs?
    • Inhibition of cell wall synthesis (do not effect humans or other eurkaryotes)
    • Inhibition of protien synthesis (ribosomes)
    • Inhibition of nucleic acid synthesis (nucleus)
    • Inhibition of metabolic pathways (mitochondria)
    • Interference with cell membrane integrity
  15. What are natural penicillins?
    • Narrow spectrum
    • Effective against gram + and - cocci
  16. What are broad spectrum penicillins?
    • Penicillins that has a modified side chain
    • Effective against gram + and -
  17. How does vancomycin work?
    • Inhibits formation of glycan chain
    • Must be given intravenously due to poor absorption in digestive tract
    • Important in treating infections caused by penicillin resistant gram + organisms
  18. What are cephalosporins?
    Broad range of antibiotics that are resistant to beta lactams
  19. What is Bacitracin?
    • Common ingredient in non-prescription first aid ointments
    • Highly toxic
    • Can only use topically
  20. Which antibiotics inhibit protien synthesis?
    • Aminoglycosides
    • Tetracyclins
    • Streptogramins
  21. How does streptomycin work?
    Causes misreading of mRNA
  22. How do tetracyclins work?
    • Blocks attachment of tRNA to ribosome
    • Causes discoloration of teeth if taken as a young child
  23. How does ciprofloxacin (a fluoroquinolones) work?
    Inhibits action of DNA enzyme
  24. What does inhibiting the metabolic pathway do?
    Inhibit the production of folic acid
  25. What is polymixin B?
    • Common ingredient in first aid ointments
    • Can bind to eukaryotic cells (humans)
    • Limited to topical use
  26. What is MIC?
    • Minimum Inhibitory Concentration
    • Smallest effective dose
  27. How is MIC determined?
    • By examining strains ability to grow in broth containing different concentrations of test drug
    • Serial Dilution - Test tubes inpregnanted
    • Disc Diffusion Method - Discs impregnated with antibiotic and placed on plate
    • E-test - Strips impregnated with antibiotic
  28. What are the 2 types of "Acquisition of Resistance?"
    • Spontaneous Mutation - Natural alteration of existing genes, relatively rare
    • Acquisition of New Genes - Occurs most commonly by conjugation
  29. What are some emerging examples of antimicrobial resistance?
    • Enterococci - some strains now resistant to vancomycin, Termed - "Vancomycin Resistant Enterococcus" or "VRE"
    • MRSA - strain of staphylococcus arueus now resistant to Methicillin
    • Streptococcus pneumoniae - some strains have gained resistance to penicillin
  30. What is the mechanism of action for antiviral drugs?
    Viral uncoating - prevents severity and duration of disease