control of microbial growth

Question 1

define sterilization

Answer 1

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

Question 2

what does sterilization remove

Answer 2

EVERYTHING (organisms and spores)

Question 3

T or F: sterilization removes spores

Answer 3

true

Question 4

define disinfection

Answer 4

killing/inhibiting/removing pathogenic organisms

Question 5

does disinfection kill everything?

Answer 5

no; it kills/removes PATHOGENS

Question 6

what is used to disinfect

Answer 6

disinfectants

Question 7

define sanitization

Answer 7

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

Question 8

define antisepsis

Answer 8

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

Question 9

goal of sanitization?

Answer 9

reduce microbes to safe levels for the public

Question 10

goal of antisepsis?

Answer 10

prevent infection on living tissue by destroying microbes

Question 11

what are antiseptics

Answer 11

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

Question 12

list 2 antiseptics

Answer 12

iodine or alcohol

Question 13

what does “cide” mean in cidal agent

Answer 13

the agent kills

Question 14

what does “static” mean in static agent

Answer 14

the agent inhibits growth

Question 15

which kills: cidal or static agents

Answer 15

cidal

Question 16

which inhibits: cidal or static agents

Answer 16

static

Question 17

are enveloped viruses and bacteria susceptible or resistant to antimicrobial agents

Answer 17

susceptible

Question 18

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

Answer 18

resistant

Question 19

how does population size influence the efficacy of antimicrobial methods

Answer 19

larger populations take longer to kill than small populations

Question 20

do small or large populations of bacteria take longer to kill

Answer 20

large

Question 21

how does population composition influence the efficacy of antimicrobial methods

Answer 21

microbes differ markedly in their sensitivity to antimicrobial agents

Question 22

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

Answer 22

higher concentrations/intensities kill more rapidly

Question 23

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

Answer 23

longer exposure to the agent = more organisms killed

Question 24

how does temperature influence the efficacy of antimicrobial methods

Answer 24

higher temperatures usually increase the amount of killing

Question 25

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

Answer 25

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

Question 26

what is the mode of action for heat as an antimicrobial

Answer 26

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

Question 27

what are the two types of heat used as an antimicrobial

Answer 27

moist heat and dry heat

Question 28

what are the three types of moist heat

Answer 28

boiling, autoclaving, and pasteurization

Question 29

does boiling sterilize

Answer 29

no

Question 30

if boiling doesn't sterilize, what does it do

Answer 30

disinfects

Question 31

what does boiling kill

Answer 31

most bacteria, but not spores

Question 32

what doesn't boiling kill

Answer 32

spores

Question 33

how does autoclaving work

Answer 33

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

Question 34

what autoclaving conditions do we use

Answer 34

121 C and 15 psi

Question 35

what does autoclaving kill

Answer 35

all vegetative bacteria and spores

Question 36

does autoclaving sterilize

Answer 36

yes

Question 37

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

Answer 37

time increases as volume increases

Question 38

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

Answer 38

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

Question 39

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

Answer 39

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

Question 40

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

Answer 40

true; this is because of the high pressure conditions

Question 41

what two types of indicators can be used in the autoclave

Answer 41

chemical or biological

Question 42

describe a chemical indicator in the autoclave

Answer 42

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

Question 43

what is the downside of autoclave tape

Answer 43

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

Question 44

describe how a biological indicator of the autoclave works

Answer 44

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

Question 45

does pasteurization sterilize

Answer 45

no (for the most part)

Question 46

if pasteurization doesn't sterilize, what does it do

Answer 46

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

Question 47

list the 3 different pasteurization processes

Answer 47

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

Question 48

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

Answer 48

68.2C for 30 min

Question 49

what is low-temp holding used for

Answer 49

beer, fruit juice, smaller volumes of milk

Question 50

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

Answer 50

72C for 15 sec

Question 51

what is high-temp short-time used for

Answer 51

industry milk and other dairy products

Question 52

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

Answer 52

138C for 3 sec

Question 53

what is ultra-high temp used for

Answer 53

milk that doesn't require refrigeration until opened

Question 54

which type of pasteurization sterilizes

Answer 54

ultra-high temp

Question 55

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

Answer 55

incineration and the oven

Question 56

what is incineration

Answer 56

used in the place of an alcohol lamp/bunsen burner

Question 57

does incineration sterilize

Answer 57

yes

Question 58

what is the oven/ how do you use it

Answer 58

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

Question 59

does the oven sterilize

Answer 59

yes

Question 60

what types of materials do we use dry heat for

Answer 60

powders, materials that can become damaged by steam

Question 61

what materials CANT we use dry heat for

Answer 61

certain materials (ie rubber and plastics)

Question 62

what are two methods of low temps as antimicrobial

Answer 62

refrigeration and freezing

Question 63

what temp range is refrigeration

Answer 63

0-7 C

Question 64

what temp range is freezing

Answer 64

below 0 C

Question 65

do low temps sterilize?

Answer 65

no

Question 66

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

Answer 66

they decrease microbial metabolism and growth

Question 67

are low temps cidal or static

Answer 67

static

Question 68

low temps are ___static

Answer 68

bacteriostatic

Question 69

how does desiccation work

Answer 69

removes liquid water which inhibits microbial growth

Question 70

what is lyophilization

Answer 70

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

Question 71

what is the final product of lyophilization

Answer 71

a powdered pellet

Question 72

what is filtration as an antimicrobial method

Answer 72

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

Question 73

does filtration sterilzie

Answer 73

yes!

Question 74

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

Answer 74

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

Question 75

describe two ways how we can filter air

Answer 75

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

Question 76

describe how osmotic pressure is used as an antimicrobial agent

Answer 76

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

Question 77

list two types of radiation that control microbial growth

Answer 77

ionizing and non ionizing

Question 78

what is an example of ionizing radiation

Answer 78

gamma rays

Question 79

how does ionizing radiation work

Answer 79

penetrates deep into objects

Question 80

does ionizing radiation sterilize

Answer 80

yes

Question 81

what is ionizing radiation used for

Answer 81

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

Question 82

give an example of non ionizing radition

Answer 82

UV light

Question 83

wavelength of UV light?

Answer 83

260 nm

Question 84

does nonionizing radition sterilize

Answer 84

yes

Question 85

how does non ionizing radiation work

Answer 85

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

Question 86

what is non ionizing radiation used for

Answer 86

air, transparent fluids, surfaces of objects