chapter 12

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chapter 12
2012-04-22 15:57:34

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  1. the killing or removal of all microorganisms in a material on on an object
  2. means there are no living organisms in or on a material
  3. reducing the number of pathogenic organisms on objects or in materials so that they pose no threat of disease
  4. agents typically applied to inanimate objects
  5. agents applied to living tissue
  6. what are the 3 prinicples of the control of microbial growth
    • 1) a definate proportion of the organisms die in a given time interval
    • 2) the fewer organisms present, the shorter the time needed to achieve sterility
    • 3) microorganisms differ in their susceptibility to antimicrobial agents
  7. bacteria killing
  8. bacterial growth inhibiting
  9. a numerical expression for the effectiveness of a disinfectant relative to that of phenol
    phenol coefficient
  10. when did Lister introduce phenol (carbolic acid) as a disinfectant?
  11. method of evaluating the antimicrobial properties of a chemical agent using filter paper diskc placed on an innoculated agar plate
    filter paper disk method
  12. a method of evaluating the antimicrobial properties of a chemical agent using standard preparations of certain test bacteria
    use-dilution test
  13. what 6 qualities should be considered in deciding which disinfectant to use
    • 1) be fast acting even in the presence of organic substances, such as those in body fluids
    • 2) be effective against all types of infectious agents without destroying tissue or acting as a poison if ingested
    • 3) easily penetrated material to be disinfected without damaging or discoloring the material
    • 4) be easy to prepare and stable even when exposed to light, heat, or other environmental factors
    • 5) be inexpensive and easy to obtain and use
    • 6) no unpleasant odor
  14. althoug the kinds of reactions are almost as numerous as the agents themselves, agent can be grouped together by what they affect _, _, and _.
    • proteins
    • membranes
    • other cell components
  15. alteration of protein structure
  16. soluble compounds that reduce surface tension, just as soaps and detergents break up grease particles in dishwater and include alcohols, detergents, and quaternary ammonium compounds.
  17. often used with other chemical agents to help the agent penetrate fatty substances
    wetting agents
  18. Alkylating agents such as ethylene oxide, nitrous acid, and hydroxylamine, act as chemical mutagens altering _ or _.
    DNA or RNA
  19. what is selenium used in
    head and shoulders
  20. what is used in the eyes of newborns to prevent gonococcal infections
    silver nitrate
  21. what is merthiolate and mercurochrome used for
    to disinfect skin wounds
  22. what is tincture
    an alcoholic solution
  23. what are chlorine and bromine
  24. what solution is better 70% alcohol or 99% alcohol
    70% is better
  25. does alcohol sterilize or disinfect skin
    alcohol disinfects but does not sterilize skin because it evaporates quickly and stays in contact with microbes for only a few seconds
  26. what are lysol, cresols (creosote), hibiclens
  27. what is hydrogen peroxide
    oxidizing agent, oxygen kills the obligate anaerobes present in the wounds. Good for puncture wounds
  28. disrupts both the proteins and the nucleic acids. i.e. formaldehyde, ethylene oxide
    alkylating agents
  29. what are the specific chemical antimicrobial agents we talked about in class
    • soaps and detergents
    • acids and alkalis
    • heavy metals
    • halogens
    • alcohols
    • phenols
    • oxidizing agents
    • alkylating agents
    • dyes
    • other agents
  30. what are some of the other agents that have microbial effects
    sodium nitrite, antifreeze, certain plant oils like thymol, eugenol, sulfites, sulfur dioxide, sodium diacetate, garlic onions
  31. the temp that kills all the bacteria in a 24-hour-old broth culture at neutral pH in 10 minutes
    thermal death point
  32. the time required to kill all the bacteria in a particular culture at a specified temp
    thermal death time
  33. the length of time needed to kill 90% of the organisms in a given population at a specified temp
    decimal reduction time - AKA DRT or D value
  34. what are the types of applications/antimicrobial agents used to kill bacteria or slow the growth
    • dry heat
    • moist heat
    • pasteurization
    • refrigeration
    • freezing
    • freeze-drying
    • radiation
    • sonic and ultrasound waves
    • filtration
    • osmotic pressure
  35. what is the #1 way to sterilize
    dry direct heat
  36. uses pressure and temp to sterilize. i.e. autoclave
    moist heat
  37. what 2 rules must be followed with an autoclave
    • 1) articles must be placed in the autoclave so that steam can easily penetrate them
    • 2) air should be evacuated so that the chamber fills with steam
  38. pasteurization is not, is not, is not a form of
  39. what are the methods that can be used in pasteurization
    • flash method - up to 71.6C for 15 seconds
    • holding method - 62.9C for 30 minutes
  40. what is ultrahigh temperature processing (UHT)
    raises the temp from 74C to 140C and then drops it back to 74C in less than 5 seconds
  41. slows the growth of bacteria and helps prevent spoiling of foods
  42. stops bacterial growth for the time being
  43. the removal of water inhibits the action of enzymes and preserves foods
  44. the drying of material from the frozen state
  45. what are the 4 types of radiation used
    • UV light - most effective in killing microorganisms by damaging DNA and proteins
    • Ionizing radiation - x-rays and gamma rays
    • Microwave radiation - only useful when heating items that contain water
    • strong visible light - sunlight has bactericidal effects
  46. with sonic and ultrasonic waves what are cavitation and sonication
    • cavitation is the formation of a cavity inside the cytoplasm of a cell
    • sonication is the disruption of cells by sound waves
  47. the passage of materials through a filter or straining device
  48. thin disks with pores that prevent the passage of anything larger than the pore size
    membrane filters
  49. high concentrations of salt, sugar, or other substances create a hyperosmotic medium which draws water from the microorganisms by _.
  50. loss of water, severely interferes with cell function and eventually leads to cell death
  51. germicidal
    kills microbes
  52. viricidal
    inactivates viruses
  53. bacteriocidal
    kills bacteria
  54. bacteriostatic
    stops bacterial growth
  55. sporicidal
    kills bacterial endospores and fungal spores
  56. fungicidal
    kills yeasts and molds
  57. Which term is used to describe the reruction in number if pathogenic organisms on objects or in material so that they do not pose a disease threat:
    A) lyophilization
    B) disinfection
    C) decontamination
    D) sterilization
    E) sanitization
    B) disinfection
    (this multiple choice question has been scrambled)
  58. true or false
    when something is sterilized, there are levels or degrees which are reached for that object's or material's sterility.
  59. Which of the following is true of the phenol coefficient test?
    a) uses S. typhi and S. aureus
    b) uses phenol as the standard chemical against which other chemicals are compared
    c) if a chemical has a phenol coefficient less than 1.0, it is less effetive than phenol
    d) it is particularly reliable for chemicals derived from phenol
    e) all of the above
    e) all of the above
  60. surfactant damages
    membrane lipid disruption
  61. alkylating agents damage
    • protein denaturation
    • nucleic acid alteration
  62. oxidation agents damage
    protein denaturation
  63. detergents damage
    membrane lipid disruption
  64. hydrolyzing agents damage
    protein denaturation
  65. heavy metals damage
    protein denaturation
  66. crystal violet dye damage
    cell wall formation
  67. refrigeration, freezing, drying, and freeze-drying _ the growth of microorganisms but does not usually _ them. Dry heat, moist heat under pressure, and open flame are much more effective in killing microbes by _ proteins, melting _, and incineration.
    • retard
    • kill
    • denaturing
    • lipids
  68. The pasteurization process does which of the following to milk:
    A) it kills microbial pathogens that might be present in milk
    B) it sterilizes milk
    C) it kills all microbes
    D) it inactivates viruses
    E) it kills all bacterial spores
    A) it kills microbial pathogens that might be present in milk
    (this multiple choice question has been scrambled)
  69. true or false
    the advantage of UV-radiation disinfection is that it readily penetrates through most samples.
  70. which of the following are reasons ehy UV light might be expected to be less effective in killing bacteria:
    A) UV light cannot penetrate glass, cloth, paper, or most materials under which microbes might be located
    B) UV light can penetrate air
    C) small DNA-binding proteins in bacterial spores make the DNA resistant to UV light damage
    D) UV light kills fewer bacteria than expected because of their DNA repair mechanisms
    E) UV light source gain intensity over time
    A) UV light cannot penetrate glass, cloth, paper, or most materials under which microbes might be located
    (this multiple choice question has been scrambled)
  71. gamma rays and x-rays are effective in killing microorganisms because they:
    A) damage DNA
    B) all of these
    C) dislodge electrons from atoms, creating ions
    D) none of these
    E) produce powerful oxidizing agents (peroxides)
    B) all of these
    (this multiple choice question has been scrambled)
  72. quaternary ammonium compounds (quats) are a type of:
    A) alkylating agent
    B) phenolic substance
    C) basic solution
    D) soap
    E) detergent
    A) alkylating agent
    (this multiple choice question has been scrambled)
  73. the active antimicrobial ingredient in bleach is:
    A) Phenol
    B) hydrochloride
    C) iodine
    D) bromide
    E) hypochloride
    E) hypochloride
    (this multiple choice question has been scrambled)
  74. what are phenol derivatives used for
    • instrument disinfection
    • skin disinfection
  75. what is iodine used for
    skin disinfection
  76. what are alcohols used for
    skin disinfection
  77. what are acids used for
    food preservation
  78. what is chlorine used for
    water disinfection
  79. what are oxidizing agents used for
    puncture wound disinfection
  80. what are nitrates used for
    food preservation
  81. heat-sensitive materials (rubber and plastic) and bulky materials (mattresses) can be sterilized using:
    A) dry heat
    B) UV radiation
    C) autoclaving
    D) gaseous ethylene oxide
    E) none of these
    D) gaseous ethylene oxide
    (this multiple choice question has been scrambled)
  82. true or false
    In the process of autoclaving it is the increased temperature and not the increased pressure that kills all microbes including spores and the nucleic acids of viruses.
  83. the minimum time used for sterilization by autoclaving is:
    A) 15 min
    B) 1 hour
    C) 5 min
    D) 34 min
    E) 2 hours
    A) 15 min
    (this multiple choice question has been scrambled)
  84. which of the following is a limitation of the autoclave:
    A) use with heat-sensitive materials
    B) ability to kill endospores
    C) use with glassware
    D) length of time
    E) ability to inactivate viruses
    A) use with heat sensitive material
    (this multiple choice question has been scrambled)
  85. the recommended method for testing that an autoclave has truely sterilized a load uses:
    A) bacteriophages
    B) staphylococcus aureus
    C) mycobacterium tuberculosis
    D) bacillus stearothermophilus
    E) influenza virus
    D) bacillus stearothermophilus
    (this multiple choice question has been scrambled)
  86. microwave ovens will only heat materials that contain:
    A) protein
    B) foos containing substrates
    C) lipid
    D) water
    E) metals, such as calcium or iron
    D) water
    (this multiple choice question has been scrambled)
  87. what does a researcher have to do in order to kill all bacteria in a liquid without damaging heat-labile proteins in the solution:
    a) pass the liquid through a 0.5um filter
    b) autoclave the solution
    c) pass liquid through a 0.22um filter
    d) boil the solution
    e) lower the pH of the solution
    • c) pass the liquid through a 0.22um filter
    • a few bacteria can fit through the 0.45um filter
    • most bacteria is 1.2um filter
  88. how does the presence of high concenrations of salt or sugars in food prevent growth of microorganisms:
    A) it sets up an environment high in osmotic pressure resulting in cellular plasmolysis (water loss)
    B) a and b
    C) it sets up an isotonic environment in which cells die
    D) it sets up a hypotonic environment causing the cells to lyse
    e) none of the above
    A) it sets up an enviroment high in osmotic pressure resulting in cellular plasmolysis (water loss)
    (this multiple choice question has been scrambled)
  89. how does the process lyophilization work in order to preserve microorganisms:
    A) the process allows large ice crystals to form inside the cell ensuring their preservation
    B) the process works by removing both water and contaminating organisms under vacuum
    C) rapidly frozen organisms in vials are subjected to a vacuum instrument that removes water from them and seals the vials under vacuum
    D) the rapid freeze-thaw cycles allow for rapid cryopreservation
    e) all of the above
    C) rapidly frozen organisms in vials are subjected to a vacuum instrument that removes water from them and seals the vials under vacuum
    (this multiple choice question has been scrambled)
  90. which of the following effects the elimination bacteria from an object:
    a) number of bacteria present
    b) temp
    c) pH
    d) presence of organic matter
    e) all of the above
    e) all of the above
  91. sensitivity is shown on the kirby-bauer method by a _
    large zone of inhibition
  92. a resistance is shown in the kirby-bauer method by a
    small zone of inhibition or no zone at all
  93. why are the resistant and sensitive zones different and not standard
    some chemical agents my have molecules that are able to travel faster or farther through agar than other agents