chapter 13

  1. who coined the term chemotherapy
    Paul Ehrlich
  2. the use of chemical substances to kill pathogenic organisms without injuring the host. Today it refers to the use of chemical substances to treat various aspects of disease
  3. any chemical substance used in medical practive
    chemotherapeutic or drugs
  4. a special group of chemotherapeutic agents used to treat diseases caused my microbes
    antimicrobial agent
  5. against life
  6. in the 1940s Selman Waksman discovered streptomycin and defined it as an_.
  7. a chemical substance produced by microorganisms which has the capacity to inhibit the growth of bacteria and even destroy bacteria and other microorganisms in dilute solution
  8. an antimicrobial agent synthesized chemically in the lab
    synthetic drug
  9. who isolated penicillin and worked with other researchers to develop methods of mass production. purified and reduced to not be toxic.
    Ernst Chain and Howard Florey
  10. it must harm the microbes without causing significant damage to the host
    selective toxicity
  11. amount of a drug necessary to cause host damage
    toxic dosage level
  12. level of drug dosage that successfully elimiantes a pathogenic organism if maintained over a period of time
    therapeutic dosage level
  13. the amximum tolerable dose os a particular drug per kilogram of body weight divided by the minimum dose per kilogram body weight that will cure the disease
    chemotherapeutic index
  14. the range of different microbes against which an antimicrobial agent acts
    spectrum of activity
  15. agents that are effective against both gram-positive and gram-negative bacteria
    broad spectrum
  16. agents that are effective only against a small number of organisms
    narrow spectrum
  17. what happens if gram-negative bacteria are killed too fast
    they release lipoprotein which is toxic and if they are killed too fast then it will harm the host by becoming toxic
  18. what are the 5 different modes of action of antimicrobials
    • 1) inhibition of cell wall synthesis - bonds to the active site and blocks enzyme action
    • 2) disruption of cell membranes function
    • 3) inhibition of protein synthesis
    • 4) inhibition of nucleic acid synthesis
    • 5) action as antimetabolites
  19. what are the 3 side effects of antimicrobial agent on infected persons
    • 1) toxicity
    • 2) allergy
    • 3) disruption of normal microflora
  20. what are the 5 mechanisms of resistance
    • 1) alteration of targets - usually effects bacterial ribosomes
    • 2) alteration of membrane permeability - occurs when new genetic info changes the nature of proteins in the membrane.
    • 3) developement of enzymes - common cause of resistance can destroy or inactivate antimicrobial agent.
    • 4) alteration of an enzyme - allows for a formerly inhibited reaction to occur
    • 5) alteration of a metabolic pathway - bypasses a reaction inhibited by an antimicrobial agent that occurs in other sulfonamide-resistant bacteria
  21. resistance against two or more similar antimicrobial agents through a common mechanism
  22. referring to an inhibitory effect producied by 2 antibiotic working together that is greater than either can acheive alone
  23. a standard quantity of the causative organism is uniformly spread over an agar plate and several filter paper disks impreganted with a secific agent are placed on the agar surface
    disk diffusion method or Kirby-Bauer method
  24. the clear area that appears on agar in the disk diffusion method, indicating where the agent has inhibited growth of the organism
    zone of inhibition
  25. what makes the zone of inhibition different for each agent
    an agent of large molecular size might be a powerful inhibitor even though it might diffuse only a small distance and produces a small zone of inhibition
  26. A method of testing antibiotics sensitivity in which organisms are incubated in a series of tubes containing known quantities of a chemotherapeutic agent
    dilution method
  27. the lowest concentration of an antimicrobial agent that prevents growth in the dilution method of determining antibiotic sensitivity
    minimum inhibitory concentration MIC
  28. determining microbial sensitivities to antimicrobial agents is done in 4 different ways
    • disk diffusion method
    • dilution method
    • serum killing power
    • automated methods
  29. test used to determine effectiveness of an antimicrobial agent in which a bacterial suspension is added to the serum of a patient who is receiving an antibiotic and incubated
    serum killing power
  30. What are the 8 attributes of an ideal antimicrobial agent
    • 1) Solubility in body fluids - agents must dissolve in body fluids
    • 2) Selective toxicity - must be more toxic to microorganisms than host cells
    • 3) toxicity not easily altered - agent shoud maintain a standard toxicity and not be made more or less toxic by interaction with food, drugs, or abnormal conditions
    • 4) nonallergenic - not elicit an allergic response
    • 5) Stability - maintenance of a constant, therapeutic concentration in blood and tissue fluids
    • 6) resistance by microorganism not easily acquired
    • 7) long shelf-life - should retain therapeutic properties over a long period of time
    • 8) reasonable cost - affordable
  31. why do antifungal treatment often cause toxic side effects
    because fungi are eukaryotic and thus similar to human cells
  32. why is it difficult to find antiviral agents that work well on viruses
    agents must act on viruses within cells without severely affecting the host cells. Currently available antiviral agents inhibit some phase of viral replication, but they do not kill the viruses
  33. why are resistant organisms found more often in hospitalized patients than among outpatients
    • 1) many sick people living in close proximity with many different kinds of infectious agents
    • 2) tend to be more severely ill than outpatients having a lowered resistance to infection because of their illness or because they are on immunosuppressant drugs
    • 3) hospitals typically make intensive use of a variety of antibiotics making a resistant strain
  34. made partly by microorganisms and partly synthetically in the lab
    semisynthetic drug
  35. use of any chemical agent in the treatment of disease
  36. made synthetically in the lab
    synthetic drug
  37. microbial-produced chemical that inhibits growth of or kills other organisms
  38. chemicals used to treat disease caused by microbes
    antimicrobial agent
  39. any chemical agent used in medical practice
    chemotherapeutic agent
  40. how has chemotherapy developed since Erlich's time
    started with the concurrent development of sulfa drugs by Gerhard Domagk, with protonsil inhibition of gram + bacteria, and antibiotics by Alexandar Flemming with penicillium mold in the 1930s. Ernst Chain and Howard Florey in the 1940s helped isolate and mass produce penicillin
  41. why do scientists study soil and water organisms when searching for new antibiotics
    many novel fungi and bacteria live there
  42. what are the differences between bacteriostatic and bactericidal disinfectants
    bacteriostatic disinfectants only prevent growth, whereas bactericidal kill microbes
  43. Inhibition cell wall synthesis
  44. disruption of cell membrane function
  45. inhibition of protein synthesis
    • erythromycin
    • streptomycin
  46. inhibition of nucleic acid synthesis
    • rifamycin
    • purine analog vidarabine
  47. antimetabolite
    • sulfanilamide
    • purine analog vidarabine
  48. an antibiotic that contains a beta-lactam ring in its structure is:

    c) tetracycline
    D) penicillin
  49. cephalosporins resemble which antibiotic in their mode of action and their structure:

    C) penicillin
  50. which of the following is not a property of an antimicrobial agent:

    C) must be effective against viral disease
  51. a narrow spectrum agent attacks a _ different microorganisms while a _ agent attacks many different microorganisms.
    • few
    • broad-spectrum
  52. penicillin is specific for bacteria because it:

    A) inhibits the cell wall synthesis
  53. doctors prescribe synergistic drug combinations to treat bacterial infections. The purpose of such treatment is to:

    c) use lower dose of antibiotics
    C) prevents microorganisms from acquiring drug resistance
  54. an antibiotic that has a broad spectrum of activity but may cause aplastic anemia is:

    A) chloramphenicol
  55. which of the following is not a way in which antifungal drugs are effective:

    D) they can induce mycorrhizae production
  56. all of the following can be side effects of antimicrobial agents except:

    D) host superimmunity
  57. the target for quinolones is:

    B) DNA replication
  58. antimetabolites that block folic acid synthesis are:

    D) sulfonamides
  59. an antimetabolite that is effective against the mycobacterium that causes tuberculosis is:

    A) isoniazid
  60. the drug of choice for treating systemic fungal infections is:

    B) amphotericin B
  61. Which of the following is not a way to determine microbial sensitivity to an antimicrobial agent:

    C) antagonism
  62. what is an inferferon
    secreted proteins elicited from virus-infected cells that induce neighboring cells to produce antiviral proteins that prevent these cells from becoming infected
  63. what drug is used to treat hantavirus plus a wide variety of unrelated viruses
  64. what drug is used to treat cytomegalovirus eye infections
  65. what drug is used to treat HIV
  66. what drug is used to treat herpesvirus infections of the genitals
  67. what drug is used to treat herpesvirus infections of the eyes
  68. chloroquine and primaquine are the agents most widely used to treat:

    D) malaria
  69. Which of the following is a reason why helminthic and protozoan diseases are difficult to treat:

    C) they have many biochemical pathways in common with man
  70. how do antihelminthic agents work:

    A) they suppress carbohydrate metabolism or act as neurotoxins
  71. resistant against 2+ antimicrobial agents
  72. resistance due to resistance plasmids (R plasmids)
    extrachromosomal resistance
  73. resistance due to microbial DNA
    chromosomal resistance
  74. microbe formerly susceptible to antibiotic action that is no longer affected by it
  75. an additive effect of 2 antibiotics
  76. microbes that are either sequestered from antibiotics or lose their cell walls rendering them nonsusceptible to antibiotic action
    nongenetic resistance
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chapter 13