Micro Chapter 10

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Micro Chapter 10
2013-10-17 22:49:48

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  1. Antimicrobial agents are a class of _________________ used in treating diseases caused by microorganisms
    chemotherapeutic drugs
  2. antibiotic
    an antimicrobial chemical produced naturally by other organisms that is used as an antibacterial agent
  3. semisythetic drugs
    result of altering the chemical structure of an antibiotic
  4. synthetics
    agents that are completely synthesized in a laboratory
  5. History of Antimicrobial agents
    • Paul Ehrlich- Chemotherapy
    • Alexander Fleming- antibiotics (penicillin)
    • Gerhard Domagk- Sulfa drugs
  6. selective toxicity
    the chemical is more toxic to the pathogen than to the host
  7. Selective toxicity is most and least effective...
    • Most between Eukaryotic and prokaryotic cells
    • Less if both are eukaryotic cells
    • Least on viruses because they use the hosts enzymes and ribosomes. Destroying virus would destroy host cell
  8. The primary mechanisms of action
    • Inhibition of Cell Wall Synthesis
    • Inhibition of Protein Synthesis
    • Disruption of Cytoplasmic Memranes
    • Inhibition of Metabolic Pathways
    • Inhibition of Nucleic Acid Synthesis
  9. Inhibition of cell wall synthesis
    involves interfering with the formation of the peptidoglycan layer in bacterial cells. Greatest for organisms that are actively growing and have a thick peptidoglycan layer (gram +)
  10. Inhibition of protein synthesis
    involves ribosomes. Difference in size of prokaryotic and eukaryotic ribosomes allows the drug to target prokaryotic ribosomes.
  11. Disruption of cytoplasmic membranes
    drugs become part of the membrane which causes the membrane to rupture. Fungal infections
  12. Inhibiting a metabolic pathway
    keeps the reactions in the metabolic pathway from happening.
  13. Inhibition of synthesis of nucleic acids
    drugs bind to prokaryotic DNA
  14. Ideal antimicrobial
    • Readily available
    • Inexpensive
    • Stable
    • Easily administered
    • Non toxic/nonallergenic
    • Selectively toxic against wide range of organisms
  15. How to evaluate a drug
    • 1. drugs range of action
    • 2. organisms sensitivity¬†
    • 3. route of administration
    • 4. drugs overall safety and side effects
  16. 3 Efficacy tests
    • Diffusion susceptibility tests
    • Minimum Inhibitory COncentration Tests
    • Minimum Bactericidal concentration test
  17. Routs of Administration 4
    • Topical drugs
    • Oral drugs
    • Intramuscular administration
    • Intravenous administration
  18. Topical drugs
    effective for surface infections
  19. Oral drugs
    simplest to administer

    • but the concentration is usually diluted by the time it gets to infection site
    • Sometimes never makes it there
    • Self administer
  20. Intramuscular administration

    may lack potency and takes time to reach the site
  21. Intravenous adminitration
    • fastest delivery¬†
    • greatest concentration of drug
  22. Side Effects
    • Toxicity
    • Allergies
    • Disruption of normal microbiota
  23. Toxicity
    occurs when drug attacks or has an adverse effect on the host. Involves damage to organs and unborn fetus
  24. Allergies
    allergic reaction or inappropriate immune response.
  25. Disruption of Normal Microbiota
    natural flora is disrupted, inhibited or killed, causing opportunistic organisms to cause secondary infecions
  26. Mechanisms of resistance
    • production of enzymes that inhibit or destroy a drug
    • pathogen finds a way to stop entery of the drug into the organism
    • Pathodens can change the drugs target such as receptor site or a metabolic pathway
    • Pathogens are even able to pump the drug back out of their cells
  27. Multiple resistance
    pathogens resistant to 3 drugs
  28. cross resistance
    pathogens become resistant to similar drugs