Micro 20

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  1. Who was Paul Ehrlich
    • German physician and bacteriologist
    • began searching for "magic bullet", a drug that would kill a microbial pathogen w/o harming the human host
    • Was looking for sure for syphilis
    • The 606 drug compound he tested proved highly effective in txing dx in lab animals
    • Drug called Salvarsan
  2. Who was Gerhard Domagk
    discovered red dye called Protosil which could be used to treat streptococcal infections in animals
  3. chemotherapeutic agents
    chemicals used to treat disease
  4. Who were Ernst Chain and Howard Florey
    successfully purified penicillin compound
  5. antibiotics
    antimicrobial drugs naturally produced by microorganisms
  6. selective toxicity
    exhibited by antimicrobial drugs, as they cause greater harm to microbes than to human host
  7. therapeutic index
    the lowest dose toxic to patient divided by dose typically used for therapy
  8. Bacteriostatic
    inhibits bacterial growth
  9. bactericidal
    kills bacteria
  10. intrinsic (innate) resistance
    • resistance due to inherent characteristics of organism
    • Ex: If a species lacks a cells wall, will be resistant to penicillin as that's what penicillin attacks
  11. acquired resistance
    when sensitive organisms develop resistance by spontaneous mutation or horizontal gene transfer
  12. β-lactam drugs
    • bactericidal against variety of bacteria
    • Includes penicillins, cephalosporins, monobactams and carbapenems
    • Competitively inhibit enzymes that catalyze formation of peptide bridges in peptidoglycan synthesis (for cell wall)
    • These enzymes bind penicillin, which causes disruption in cell wall synthesis = weakens wall, causing cell to lyse
    • *Are bactericidal only against growing bacteria, as these cells continually synthesize peptidoglycan
  13. PBP's
    • Penicillin-binding proteins
    • enzymes that are affected by β-lactam drugs
  14. What is different btwn the different β-lactam drugs
    • the vary in their spectrum of activity
    • The peptidoglycan of gram+ is exposed on outside, drug can reach target. But Peptidoglycan of gram- is on inside preventing drug from reaching target
    • Another difference is PBP's...
  15. β-lactamase
    an enzyme that breaks the critical β-lactam ring, destroying the activity of the antibiotic
  16. Natural penicillins
    The original penicillins produced naturally by the mold Penicillium chrysogenum

    • Narrow-spectrum
    • effective against gram+ & a few gram-
    • *Bacteria that produce penicillinase are resistant to natural penicillins
  17. Penicillinase-resistant penicillins
    • Lab developed in response to penicillinase-producing Staphylococcus aureus strains
    • include methicillin and dicloxacillin

    • *Unfortunately, some penicillinase-producing bacteria acquired ability to make altered PBP's to which β-lactam no longer bind
    • S. aureus strains that can do this are called MRSA
  18. Broad spectrum penicillins
    • have modified side chains, giving them broad spectrum of activity
    • retain their activity against penicillin sensitive gram+, yet also active against gram -
    • Unfortunately, can be inactivated by β-lactamases

    *Includes ampicillin and amoxicillin
  19. Extended-spectrum penicillins
    • Have greater activity against Pseudomonas species - gram- bacteria that are unaffected by many antimicrobial drugs
    • Has less activity against gram+ bacteria
    • Include Ticarcillin and Piperacillin
  20. Penicillins + β-lactamase inhibitor
    • combo of agents
    • inhibitor interferes with activity of some types of β-lactamases, thereby protecting the penicillin against enzymatic destruction

    Includes Augmentin
  21. Vancomycin
    • blocks peptidoglycan synthesis by binding to peptide side chain of NAM molecules being assembled to form glycan chains
    • weakens cell, causing lysis
    • Used to treat C diff infections
  22. Bacitracin
    inhibits cell wall biosynthesis by interferring with transport of peptidogycan precursors across cytoplamsic membrane
  23. Aminoglycosides
    • are bactericidal drugs that irreversibly bind to 30S ribosomal subunit, causing it to distort and malfunction
    • blocks initiation of translation and causes misreading of mRNA by ribosomes that have already passed initiation step
  24. Tetracyclines
    reversibly bind to 30S ribosomal subunit, blocking the attachment of tRNA and preventing translation from continuing
  25. Glycylcyclines
    related to tetracyclines, same mechanism of action and effect, but wider spectrum of activity
  26. Macrolides
    • reversibly bind to 50S ribosomal subunit and prevent the continuation of translation
    • Often serve as drug of choice for pt's who are allergic to penicillin
  27. Chloramphenicol
    binds 50S ribosomal subunit, preventing peptide bonds from being formed and blocking translation
  28. Lincosamides
    bind to 50S ribosomal subunit and prevent continuation of translation
  29. Oxazolidinones
    bind to 50S ribosomal subunit, interfering with the initiation of translation
  30. Streptogramins
    • 2 streptogramins are administered together (quinupristin and dalfopristin) called Synercid
    • act as synergistic combo, bonding 2 different sites on 50S ribosomal subunit and inhibiting distinct steps of translation
Author
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321252
Card Set
Micro 20
Description
Micro
Updated
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