Microbiology Antibiotics

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Microbiology Antibiotics
2011-03-17 08:19:30
Microbiology Terra

Antibiotics and MOA
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  1. Interferons

    Naturally occurring agents produced when cells are infected by virus. IFN-alpha and IFN-beta trigger nonspecific reaction. Uninfected cells make antiviral proteins to protect themselves.
  2. Block attachment/Uncoating
    • Various ones prevent virus by entering host cell.
    • Example: amatadine prevents uncoating of Influenza A virus
  3. Protease inhibitors
    • Various ones specific for select protease. Inhibits proper formation of "working" proteins.
    • Viruses
  4. Griseofulvin
    • Binds to microtubules and prevents spindle apparatus formation-inhibitor of microtubules(mitosis).
    • High penetration into keratin. Used for fungal infections of the skin, nails, ringworm, athletes foot.
  5. Quinolones/Fluoroquinolones
    • Inhibits DNA gyrase, the enzyme needed for uncoiling bacterial DNA so it can be replicated-inhibits nucleic acid synthesis
    • example: ciprofloxacin (Cipro)
  6. Rifampin
    Binds to the enzyme RNA polymerase which is needed to synthesize RNA-inhibit nucleic acid synthesis
  7. Nucleoside analogs
    • Mimic the natural occurring nucleosides. mistakenly incorporated into DNA-inhibit nucleic acid synthesis
    • Virus must be actively replicating
  8. Trimethoprim
    Blocks different reaction in folic acid synthesis-interuption of metabolic pathways
  9. Sulfonamides
    Competitively inhibits PABA needed for folic acid synthesis so organism cant make nucleic acids-interuption of metabolic pathways
  10. Antisense nucleic acids
    A strand of nucleic acid complimentary to mRNA, blocks attachment of ribosomal subunits-inhibitor of protien synthesis
  11. Macrolides
    • Binds to 50S ribosome which blocks ribosome movement and prevents reading of mRNA-inhibitor of protien synthesis
    • Examples include: erythromycin, azithromycin (zithromax) and clarithromycin (biaxin)
  12. Tetracyline
    • Block the docking of the tRNA-AA to the A site of the 30S subunit-inhibitor of protien synthesis.
    • Discoloration off teeth and stunts bone growth in young children.
  13. Aminoglycosides
    • Blocks reading of mRNA by binding to 30S subunit of ribosome-inhibitor of protien synthesis.
    • Poorly absorbed orally, given IV, narrow theraputic range, otic and nephrotoxic
  14. Chloramphenicol
    • Prevents peptide bond formation between adjacent amino acids because binds to 50S subunit-inhibitors of protien synthesis
    • In bone marrow prevents incorporation of hemoglobin into RBC=aplastic anemia
  15. Azoles
    Change membrane permeability by inhibiting synthesis of ergosterol. Blocks the enzyme lanosterol a-demethylase-disrupts plasma membrane
  16. Amphotericin B
    • Attaches to ergosterol and changes membrane permeability by creating pores in the membrane-disrupts plasma membrane
    • High concentration can target cholesterol in human cells leading to nephrotoxicity
  17. Polymixin B
    • Changes membrane permeability by attaching to phospholipid (phosphatidylethanolamine) in the plasma membrane-disrupts plasma membrane
    • Also targets eukaryotic cells and can cause nephrotoxicity
  18. Echinocadins
    Inhibit synthesis of beta-glucan component of cell wall by inhibiting the enzyme 1,3 beta-glucan synthase-inhibits cell wall synthesis
  19. Isoniazid
    • Forms a complex within bacteria that blocks the enzyme, fatty acid synthase. This prevents mycolic acid production-inhibits cell wall synthesis
    • Drug of choice however used with other antimicrobials to prevent rapid resistance
  20. Vancomycin
    • inhibits transport of NAG and NAM to PTG growing points outside of plasma membrane-inhibits cell wall
    • Only used IV, Known as "mississippi mud" otic and nephrotoxicity
  21. Bacitracin
    • Inhibits transport of NAM to cell wall by blocking the transporter, bactoprenol-inhibits cell wall synthesis
    • Renal toxicity reatricts use to topical agents (triple antibiotic ointment)
  22. Beta-lactams (penicillin/cephalosporins)
    • Competitvely blocks crosslinking of NAG/NAM subunits-inhibits cell wall
    • Bacteria developed lactamases that destroy beta-lactam ring