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BIOL 2330 - microbiology > control of microbial growth > Flashcards

control of microbial growth Flashcards

1
Q

define sterilization

A

destruction or removal of all viable organisms, including spores or acellular entities, from an object or habitat

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2
Q

what does sterilization remove

A

EVERYTHING (organisms and spores)

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3
Q

T or F: sterilization removes spores

A

true

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4
Q

define disinfection

A

killing/inhibiting/removing pathogenic organisms

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5
Q

does disinfection kill everything?

A

no; it kills/removes PATHOGENS

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6
Q

what is used to disinfect

A

disinfectants

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7
Q

define sanitization

A

reduction of microbial populations to LEVELS DEEMED SAFE (based on public health standards)

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8
Q

define antisepsis

A

destruction/inhibition of microbes on LIVING TISSUE, thereby preventing infection

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9
Q

goal of sanitization?

A

reduce microbes to safe levels for the public

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10
Q

goal of antisepsis?

A

prevent infection on living tissue by destroying microbes

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11
Q

what are antiseptics

A

chemical agents that kill/inhibit growth of microbes when applied to tissue

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12
Q

list 2 antiseptics

A

iodine or alcohol

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13
Q

what does “cide” mean in cidal agent

A

the agent kills

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14
Q

what does “static” mean in static agent

A

the agent inhibits growth

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15
Q

which kills: cidal or static agents

A

cidal

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16
Q

which inhibits: cidal or static agents

A

static

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17
Q

are enveloped viruses and bacteria susceptible or resistant to antimicrobial agents

A

susceptible

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18
Q

are mycobacteria, endospores, and prions susceptible or resistant to antimicrobial agents

A

resistant

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19
Q

how does population size influence the efficacy of antimicrobial methods

A

larger populations take longer to kill than small populations

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20
Q

do small or large populations of bacteria take longer to kill

A

large

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21
Q

how does population composition influence the efficacy of antimicrobial methods

A

microbes differ markedly in their sensitivity to antimicrobial agents

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22
Q

how does concentration/intensity of antimicrobial agents influence the efficacy of antimicrobial methods

A

higher concentrations/intensities kill more rapidly

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23
Q

how does duration of exposure to the agent influence the efficacy of antimicrobial methods

A

longer exposure to the agent = more organisms killed

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24
Q

how does temperature influence the efficacy of antimicrobial methods

A

higher temperatures usually increase the amount of killing

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25
Q

how does the local environment in which a microbe is in influence the efficacy of antimicrobial methods

A

many factors can profoundly impact effectiveness, ie pH, viscosity, and concentration of organic matter

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26
Q

what is the mode of action for heat as an antimicrobial

A

denatures proteins, disrupts integrity of PM/cell wall, and is disrupts the structure/function of nucleic acids

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27
Q

what are the two types of heat used as an antimicrobial

A

moist heat and dry heat

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28
Q

what are the three types of moist heat

A

boiling, autoclaving, and pasteurization

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29
Q

does boiling sterilize

A

no

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30
Q

if boiling doesn’t sterilize, what does it do

A

disinfects

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31
Q

what does boiling kill

A

most bacteria, but not spores

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32
Q

what doesn’t boiling kill

A

spores

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33
Q

how does autoclaving work

A

makes use of saturated steam under pressure to bring the temp above 100 C

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34
Q

what autoclaving conditions do we use

A

121 C and 15 psi

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35
Q

what does autoclaving kill

A

all vegetative bacteria and spores

36
Q

does autoclaving sterilize

A

yes

37
Q

in the autoclave, how is time affected when we have lots of volume

A

time increases as volume increases

38
Q

T or F: we pack the autoclave as tight as we can to sterilize lots of stuff

A

false; the steam needs to be able to contact all surfaces, so don’t pack tightly

39
Q

T or F: we want to wrap things in tinfoil when in the autoclave

A

false; tinfoil is impermeable to steam, so anything wrapped will not be sterilized

40
Q

T or F: we want to loosen the lids of anything in the autoclave

A

true; this is because of the high pressure conditions

41
Q

what two types of indicators can be used in the autoclave

A

chemical or biological

42
Q

describe a chemical indicator in the autoclave

A

autoclave tape: lines will turn black once high heat is reached

43
Q

what is the downside of autoclave tape

A

only shows that the heat was reached, doesn’t actually confirm sterility

44
Q

describe how a biological indicator of the autoclave works

A

use a sterility indicator: a small vial has a tube that contains endospores and this is put into the autoclave. After, the vial is incubated, and if spores are present they will germinate, and we will see a color change occur

45
Q

does pasteurization sterilize

A

no (for the most part)

46
Q

if pasteurization doesn’t sterilize, what does it do

A

it eliminates any pathogenic bacteria and reduces the total number of nonpathogenic bacteria

47
Q

list the 3 different pasteurization processes

A

low-temp holding, high-temp short-time, and ultra-high temp

48
Q

what are the settings for low-temp holding (pasteurization)

A

68.2C for 30 min

49
Q

what is low-temp holding used for

A

beer, fruit juice, smaller volumes of milk

50
Q

what are the conditions for high-temp short-time (pasteurization)

A

72C for 15 sec

51
Q

what is high-temp short-time used for

A

industry milk and other dairy products

52
Q

what are the conditions for ultra-high temp (pasteurization)

A

138C for 3 sec

53
Q

what is ultra-high temp used for

A

milk that doesn’t require refrigeration until opened

54
Q

which type of pasteurization sterilizes

A

ultra-high temp

55
Q

what are the two forms of dry heat used as an antimicrobial

A

incineration and the oven

56
Q

what is incineration

A

used in the place of an alcohol lamp/bunsen burner

57
Q

does incineration sterilize

A

yes

58
Q

what is the oven/ how do you use it

A

you put something in, turn the temp to 171C for 1 hour or 160C for 2 hours

59
Q

does the oven sterilize

A

yes

60
Q

what types of materials do we use dry heat for

A

powders, materials that can become damaged by steam

61
Q

what materials CANT we use dry heat for

A

certain materials (ie rubber and plastics)

62
Q

what are two methods of low temps as antimicrobial

A

refrigeration and freezing

63
Q

what temp range is refrigeration

A

0-7 C

64
Q

what temp range is freezing

A

below 0 C

65
Q

do low temps sterilize?

A

no

66
Q

if low temps don’t sterilize, what do they do

A

they decrease microbial metabolism and growth

67
Q

are low temps cidal or static

A

static

68
Q

low temps are ___static

A

bacteriostatic

69
Q

how does desiccation work

A

removes liquid water which inhibits microbial growth

70
Q

what is lyophilization

A

culture is frozen in liquid nitrogen and then subjected to a vacuum to remove frozen water

71
Q

what is the final product of lyophilization

A

a powdered pellet

72
Q

what is filtration as an antimicrobial method

A

fluid or air passes through a sieve that will trap the desired particles

73
Q

does filtration sterilzie

A

yes!

74
Q

what size pores are in the filter paper of filtration + what is the purpose of this size

A

0.22 um will trap large viruses and most bacteria. 0.2 um is often used

75
Q

describe two ways how we can filter air

A

using an N95 mask excludes 95% of particles that are greater than 0.3 um in size (most microbes), or you can use a HEPA filter

76
Q

describe how osmotic pressure is used as an antimicrobial agent

A

high concentrations of sugar or slat inhibit microbial growth (hypertonic environment) bc this dries out the cells

77
Q

list two types of radiation that control microbial growth

A

ionizing and non ionizing

78
Q

what is an example of ionizing radiation

A

gamma rays

79
Q

how does ionizing radiation work

A

penetrates deep into objects

80
Q

does ionizing radiation sterilize

A

yes

81
Q

what is ionizing radiation used for

A

sterilization of antibiotics, surgical sutures, plastic disposable lab supplies, and food

82
Q

give an example of non ionizing radition

A

UV light

83
Q

wavelength of UV light?

A

260 nm

84
Q

does nonionizing radition sterilize

A

yes

85
Q

how does non ionizing radiation work

A

is limited to surface sterilization since it doesn’t penetrate well

86
Q

what is non ionizing radiation used for

A

air, transparent fluids, surfaces of objects

BIOL 2330 - microbiology (30 decks)

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