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microbiology exam 2 > chapter 9 > Flashcards

chapter 9 Flashcards

0
Q

how can you control growth microorganisms ?

A
  1. killing microoirganisms
  2. inhibiting growth of microorganisms
  3. removing them
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1
Q

what is meant by microbial control?

A

reduction in number and activity.

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2
Q

cidal agents=

A

kill

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3
Q

static agents=

A

inhibit

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4
Q

sterilization?

A

kills or removes all living microbes.

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5
Q

disinpection?

A

use of physical/chemical agents(disinfectants) to kill or destroy microbes

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6
Q

antispsis?

A

the process

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7
Q

antiseptic?

A

chemical agents to kill/destroy microbes in animate(living) objects

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8
Q

degerming?

A

removal of microbes

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9
Q

sanitation?

A

disinfecting plates, utensils, and others used by the public

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10
Q

pasteurization ??

A

heating to a certain temp. to kill the most resistant bacteria.
ex: mycrobial tuberculosis (milk)
CANNOT KILL ENDOSPORES

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11
Q

what is microbial death?

A
  • permanent loss of reproductive ability

- exponential (die gradually)

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12
Q

what are the mode of actions of antimicrobial agents?

A
  • alteration of cell walls and membranes

- damage of proteins and nucleic acids

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13
Q

what are the characteristics of an ideal antimicrobial method-

A
  • inexpensive *can be cheap but harmful.
  • fast acting
  • stable -harmless
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14
Q

what are the factors that affect the efficacy of antimicrobial agents?

A

-site to be treated(hospital or home)
-relative susceptibility of organisms(vegetative cells vs. endospores)
-enviromental
temp, pH, presence of organic matter

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15
Q

compare susceptibility of vegetative cells with endospores to antimicrobial agents.

A 
vegetative= active 
endospores= inactive= very resistant
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16
Q

what is the effect of temp on the action of antimicrobial agents?

A

increase temp- hasten effect of microbial agent

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17
Q

what is the effect of pH on the action of antimicrobial agents?

A

heat is effective in acid than in alkali

increase temp = decreased pH

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18
Q

what are examples of organic matter that may affect the action of antimicrobial agent?

A

sputum, blood feces, urine

organic matter presence may lower the efficiency of antimicrobial agents

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19
Q

what is the effect of the presence of organic matter on the action of antimicrobial agents?

A
  • inactivates the agent
  • protects the microbes
  • intervenes with the penetration of the agent
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20
Q

two methods of microbial control?

A

physical

chemical

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21
Q

what is the mode of action of moist heat?

A

-denatures proteins and destroys cell membrane and cell wall

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22
Q

what are examples of methods to control microorganisms using moist heat?

A
  • boiling=100 degrees C
  • autoclaving
  • pasteurization
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23
Q

what is an autoclave?

A

pressure arises, temp rises to kill moist resistant microbes

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24
Q

what happens to temp when pressure increases?

A

temp increase

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25
Q

which kill the microorganisms, the high temp or the press?

A

the temp

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26
Q

what is the time-temp requirements of sterilization using autoclave?

A

121 degrees C
15-20 mins
15 psi(pressure)

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27
Q

what is pasteurization?

A
  • traditional method
  • cannot kill endospores
    process: historical pasteurization treatment: 63 degrees C for 30min
    process: flash treatment: 72 degrees C 15 seconds
    process: ultra-high temp treatment: 134 degrees C for 1 sec
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28
Q

antimicrobial agents that would damage the cell wall of bacteria will kill the bacterial because bacteria will….

A

be susceptible to lysis.

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29
Q

is moist head cidal or static method?

A

a-cidal…. = kills bacteria

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30
Q

what is the mode of action of dry heat?

A

oxidation, reduced into ashes

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31
Q

what are examples of method to control microorganisms using dry heat?

A
  • complete incineration 1500 degrees C

- oven sterilization 1-2 hours at 160-170 degrees C

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32
Q

compare time and temp requirements of moist heat sterilization with dry heat sterilization.

A
  • *transfer of heat is faster in moist heat.

- temps are higher in dry heat but the process is slower.

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33
Q

explain why the temp is lower and time is shorter in moist heat than in dry heat sterilization ..?

A

bc the water helps to denature microbes faster… water heats up faster.

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34
Q

what is the mode of action of low temp to microbial growth?

A

stops & slows growth & decreases metabolism

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35
Q

what are examples of methods to control microorganisms using low temp?

A

-regrigerator: around 4 degrees C
-Freezer: ordinary freezer around -10 to -20 degrees C
ultracold lab freezer typically -80 degrees C

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36
Q

refrigeration and freezing is what type of method? static or cidal? why?

A

static, bc it only inhibits the growth of microbes

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37
Q

temps are important for food safety, what is meant by danger zone?

A

the zone of fastest growth.

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38
Q

what is the temp range in the danger zone?

A

60 - 4 degrees C

39
Q

phycrophils can spoil food in the _____________, and mesophiles grow faster in ___________ _________.

A
  • frige

- danger zone

40
Q

what is dessication?

A

removal of water

41
Q

how does desiccation control microorganisms?

A

action: inhibits the growth and disrupts metabolism

42
Q

what are examples of dessication methods?

A
  • drying
  • add salt
  • add sugar
43
Q

review hypertonic solutions.

A

…

44
Q

what is water activity?

A

describes amount of water available for microbial growth.

45
Q

differentiate water activity of food from moisture content of food…

A

water activity= free water; moisture content= free water& water bonded to other things.

46
Q

water activity is expressed as ___________________________

A

aw or % equilibrium relative humidity(%ERH)

47
Q

if the water activity of a certain food product is 0.4 what is the ERH?

A

4%

48
Q

what is the min. aw of the following microorganisms?

  1. normal bac 5. xerophilic molds
  2. normal yeast
  3. normal molds 6. osmpohilic yeast
  4. halophilic bac
A
  1. 0.91 (fresh meats, milk)
  2. 0.88 (dry cheese, sponge cake)
  3. 0.80 (condensed milk, flour0
  4. 0.75 (jam, marshmellows)
  5. 0.65 (rolled oats)
  6. 0.60 (dried fruits)
49
Q

what is membrane filtration? used for?

A

physically removes (degerming) microbes– used for liquid materials that can’t be sterilized.

50
Q

what are examples of equipment that use membrane filtration?

A
  • membrane filter
  • vacuum pump
  • ** microbes will be retained in the filter paper
51
Q

describe how a laminar flow biological safety cabinet works to control microorganisms…?

A

air moves away from the person, up & thru a filter & then back out.

52
Q

what are the 4 levels of safety in labs dealing with pathogens?

A
  1. bio safety level 1 = handling pathogens that don’t cause disease in healthy humans.
  2. bio safety level 2 = handling moderately hazardous agents
  3. bio safety level 3- handling microbes in safety cabinets
  4. bio safety level 4 = handling of microbes that cause severe or fatal disease.
53
Q

what are examples of ionizing radiations? what are their modes of action?

A
  • gamma rays
  • x-rays
  • both cause damage to DNA and inhibits proteins
54
Q

what is an example of non-ionizing radiations? what is its mode of action?

A
  • ultraviolet rays

* cause damage to DNA and inhibits proteins

55
Q

UV rays are __________ wave length, and ____________ energy.

A

longer, lower

56
Q

what is the mode of action in microwave cooking?

A
  • kills microbes **CIDAL

- denaturation of proteins due to heat generated

57
Q

high level disinfectants/ and antiseptics kill _______________
intermediate level disinfectants/ and antiseptics kill ______________
low level disinfectants/ and antiseptics kill ________________

A
  1. endospores and below
  2. mycobacteria and below
  3. trophozoites and below
58
Q

what are the uses of phenol and phenolics?

A

intermediate- to low level disinfectants

59
Q

what are examples of phenols and phenolics ??

A

lysol, triclosan, cresols

60
Q

how do phenols and phenolics control microorganisms?

A

denatures proteins and disrupts cell membrane

*remain effective in organic contaminants

61
Q

what are uses of alcohol?

A

intermediate-level disinfectants

62
Q

what are examples of alcohol?

A

isopropyl alcohol (70%-90%) tinctures

63
Q

how do alcohols control microorganisms?

A

denature proteins and disrupt cytoplasmic membrane.

64
Q

alcohols are effective against what microbes? can alcohol kill endospores?

A

bacterialcidal, fungicidal, virocidal, & cannot kill endospores.

65
Q

what is more effective in killing microorganisms? alcohol diluted with water or undiluted alcohol? explain.

A

70% is more effective bc water denatures proteins(or helps)

66
Q

what are examples of halogens?

A

iodine, chorine, bromine, fluorine

67
Q

what are the uses of halogens?

A

intermediate-level disinfectants and antiseptic chemicals.

68
Q

how to halogens kill microorganisms?

A

damage enzymes by oxidation or denaturation

69
Q

what is tincture?

A

mixture of water and alcohol

70
Q

what is an iodophor?

A

iodine-containing organic cpd

ex: betadine= used for surgery and injection

71
Q

what forms of chlorine are used to control microorganisms?

A
  • cl2(disinfect water)
  • Na/Ca hypochlorite (house bleach)
  • ClO2 (disinfect building, ex: 9/11)
  • Chloramine (disinfect water)
72
Q

why is bromine usually used in hot tubs?

A

bc bromine evaporates more slowly in higher temps, and last longer

73
Q

what are examples of oxidizing agents?

A

peroxides, ozone, and per-acetic acid (sterilant)=sterilizes food utensils.

74
Q

what are the uses for oxidizing agents?

A

high-level disinfectant

75
Q

how do oxidizing agents kill microorganisms?

A

oxidation of cell structures and enzymes

76
Q

what oxidizing agent is used to clean deep wounds ?

A

hydrogen peroxide.

77
Q

what oxidizing agent is used to disinfect water?

A

ozone (O3) - not antiseptic

78
Q

what oxidizing agent is used to sterilize food processing equiptments?

A

per-acetic acid

sporocide- kill bacterial endospores

79
Q

what are surfactants ?

A

reduce surface tension

80
Q

what are examples of surfactants?

A

-soaps (degerming agents)
-detergents
quats- benzalkonium chloride, cetylpyridinium chloride

81
Q

what are the uses for surfactants ?

A

low-level disinfectants

82
Q

how do surfactants control microorganisms?

A

disrupts cell membranes

83
Q

what are examples of heavy metals?

A

Zn, Hg, Ag, Cu

84
Q

what are the uses of heavy metals?

A

low-level bacteriostatic, fungistatic agents

*static= inhibits growth

85
Q

how do heavy metals kill microorganisms?

A

denatures proteins and interferes with S groups in proteins.

86
Q

what heavy metal is used to treat ophthalmic gonorrhea ?

A

1% Soln AgNo3- silver nitrate

87
Q

what heavy metal is used to treat burns?

A

silver sulfadiazine

88
Q

what heavy metal is used to kill algae in swimming pools?

A

CuSo4- copper sulfate - algicide=kill

89
Q

what are examples of gaseous agents?

A

ethylene oxide, propylene oxide, B propiolactone

90
Q

what are the uses of gaseous agents?

A

high-level disinfectants.

in closed chambers to sterilize items (bed, pillows)

91
Q

how do gaseous agents kill microorganisms?

A

denatures proteins and DNA by cross-linking functional groups

92
Q

what are the methods used to evaluate the efficiency of disinfectants and antiseptics? describe each…

A
  • phenol coefficient
  • use-dilution test
  • kelsey-sykes capacity test(standard method in european countries)
  • in-use test (most effective)
  • disk-diffusion method:filter paper, zone of inhibiton…
93
Q

zone of clearing = ?

A

no growth

94
Q

examples of in-use test

A

control: counter without backdown
treated: counter with backdown

95
Q

tincture of iodine =?

A

halogen

96
Q

mercorochrome = ?

A

heavy metal

microbiology exam 2 (4 decks)

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