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Veterinary Microbiology > Controlling Microbial Growth > Flashcards

Controlling Microbial Growth Flashcards

1
Q

define sterilization

A

destruction or removal of all viable organisms

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2
Q

define disinfection

A

killing, inhibition, or removal of diseases causing (pathogenic) organisms

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3
Q

what are disinfectants?

A

agents, usually chemical, used for disinfection, usually used on inanimate objects

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4
Q

define sanitization

A

reduction of microbial population to levels deemed safe (based on public health standards)

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5
Q

define antisepsis

A

prevention of infection of living tissue by microorganisms

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6
Q

what are anitseptics?

A

chemical agents that kill or inhibit growth of microorganisms when applied to tissue

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7
Q

what is chemotherapy?

A

use of chemical to kill or inhibit growth of microorganisms within host tissue

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8
Q

what do -cidal agents do? give examples

A

kill, bactericides, fungicides, viricides

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9
Q

what do static agents do?

A

inhibit growth; include bacteriostatic and fungistatic

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10
Q

when an agent is applied, do microbes die instantly?

A

nope

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11
Q

how does population death occur?

A

exponentially usually

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12
Q

what is a measure of an agent’s killing efficiency?

A

decimal reduction time, the time it takes the agent to kill 90% of population

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13
Q

what do you need to be sure of when killing microbes? why?

A

make sure all viable but nonculturable cells are dead, because once they recover they could regain ability to reproduce and cause infection

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14
Q

what are the 4 main methods of microbial control?

A
  1. physical
  2. chemical
  3. mechanical
  4. biological
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15
Q

what are the 2 categories of physical agents?

A
  1. heat

2. radiation

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16
Q

what are the 2 types of heat?

A
  1. dry

2 moist

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17
Q

what are the 2 methods of dry heat and what is the result of each?

A
  1. incineration: sterilization

2. dry oven: sterilization

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18
Q

what are the 2 methods of moist heat and what are the results of each?

A
  1. steam under pressure: sterilization

2. boiling water, hot water, pasteurization: disinfection

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19
Q

what are the 2 types of radiation?

A
  1. ionizing

2. non-ionizing

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20
Q

what is the method of ionizing radation and what is the result?

A

X-rays, cathode, gamma rays: sterilization

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21
Q

what is the method of non-ionizing radiation and what is the result?

A

UV: disinfection

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22
Q

what are the 2 types of chemical agents?

A
  1. gases

2. liquids

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23
Q

what are the 2 results with gas chemical agents?

A

can either sterilize or disinfect

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24
Q

what are the 2 types of liquid chemical agents?

A
  1. for animate objects

2. for inanimate objects

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25
Q

what are the 2 types of animate liquid chemical agents?

A
  1. chemotherapy

2. antispesis

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26
Q

what are the 2 results of inanimate liquid chemical agents?

A

can either sterilize or disinfect

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27
Q

what are the 3 types of biological agents? what are the results of each

A
  1. predator: antisepsis
  2. virus: antisepsis
  3. toxin: sterilization
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28
Q

what are the 2 methods of mechanical agents?

A
  1. filtering liquids

2. filtering air

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29
Q

what is the mechanical method?

A

filtration

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30
Q

describe filtration (2)

A
  1. reduced microbial population or sterilizes solutions of heat-sensitive microorganisms
  2. also used to reduce microbial populations in the air
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31
Q

name and describe what is used for filtering liquids

A

membrane filters: porous membranes with defined pore sizes that remove microorganisms primarily by physical screening

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32
Q

list 2 methods of filtering air

A
  1. surgical masks

2. HEPA filters (high-efficiency particulate air)

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33
Q

what are HEPA filters used in?

A

laminar flow biological safety cabinets, like in our lab

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34
Q

what does moist heat destroy? (3)

A
  1. viruses
  2. fungi
  3. bacteria
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35
Q

what does boiling NOT do? (2)

A
  1. no destroy endospores

2. does not sterilize

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36
Q

what does moist heat do? (mechanism) (3)

A

degrades nucleic acids, denatures proteins, and disrupts membranes

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37
Q

at what temperature is steam sterilization performed and what does it require?

A

above 100 degrees celsius and requires saturated steam under pressure

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38
Q

what is used for steam sterilization?

A

an autoclave

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39
Q

what is steam sterilization effective against?

A

all types of microbes including endospores

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40
Q

what is pasteurization?

A

controlled heating at temps well below boiling

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41
Q

what is pasteurization used for and why?

A

milk, beer, and other beverages because it kills present pathogens (but doesn’t sterilize) and slows spoilage by reducing total load of present microbes with not affecting nutritional content too much

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42
Q

what is the effectiveness of dry heat sterilization compared to moist heat?

A

less effective, requires higher temperatures and longer times

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43
Q

describe the process of dry heat sterilization

A

items subjected to 16- to 170 degrees celsius for 2-3 hours

44
Q

what is the mechanism of dry heat sterilization? (2)

A

oxidizes cell contituents and denatures proteins

45
Q

what are 2 advantages of dry heat sterilization compared to moist heat?

A
  1. does not corrode glassware and metal instrumnets as moist heat does
  2. equipment less expensive than an autoclave for moist heat
46
Q

give an example of dry heat sterilization

A

bench top incinerators (bunsen burners) used to flame innoculating loops in microbio labs

47
Q

what wavelength of UV radiation is most bactiericdal and why?

A

260 because DNA absorbs

48
Q

what is the mechanism of UV radiation as a control of microbial growth?

A

causes thymine dimers, preventing replication and transcription of DNA

49
Q

what is UV radiation sterilization limited to and why?

A

limited to surface sterilization because it does not penetrate glass, dirt films, water, or other substances

50
Q

what has UV radiation sterilization been used for?

A

water treatment

51
Q

describe ionizing radiation

A

gamma radiation penetrates deep into objects

52
Q

describe efficacy of ionizing radiation (what destroy and not destroy)

A

destroys bacterial endospores but not always effective against viruses

53
Q

what is ionizing radiation sterilization used for?

A

sterilization and pasteurization of anitbiotics, hormones, sutures, plastic disposable supplies, and food

54
Q

describe when disinfection is ideally effective

A

ideally effective against a wide variety of infectious agents at low concentrations and in the presence of organic matter

55
Q

describe a drawback of antisepsis

A

overuse of antiseptics such as triclosan had selected for triclosan-resistant bacteria

56
Q

list the 7 chemical agent categories

A
  1. phenolics
  2. heavy metals
  3. alcohols
  4. quarternary ammonium compounds
  5. halogens
  6. aldehydes
  7. sterilizing gasses
57
Q

what was the first widely used chemical disinfectant category?

58
Q

where are phenolic chemical disinfectants commonly used?

A

laboratories and hospitals

59
Q

how do phenolic chemical disinfectants work? (mechanism) (2)

A

act by denaturing proteins and disrupting cell membranes

60
Q

give 3 advantages of phenolic chemical disinfectants

A
  1. tuberculocidal
  2. effective in the presence of organic material
  3. long lasting
61
Q

give 2 disadvantages of phenolic chemical disinfectants

A
  1. disagreeable odor

2. can cause skin irritation

62
Q

give 2 examples of phenolic chemical disinfectants

A
  1. pine sol

2. lysol

63
Q

what category of chemical agents is among the most widely used disinfectants, antiseptics, and sanitizers?

64
Q

what are the 2 most common alcohol chemical agents?

A
  1. ethanol

2. isopropanol

65
Q

describe the 3 -idals of alcohols

A
  1. bactericidal
  2. fungicidal
  3. NOT sporicidal
66
Q

what can alcohols dod in terms of viruses?

A

inactivate some of them

67
Q

what is the mechanism of alcohol chemical agents? (2)

A

denature proteins and possible dissolve membrane lipids

68
Q

describe the drawback of alcohol chemical agents, and what kind of situation they are better used in because of it

A

they evaporate pretty quickly (why they didn’t cause a zone of inhibition in the lab) so they work better in a kill-on-contact kind of way

69
Q

what are the 2 types of halogen chemical agents?

A
  1. iodine

2. chlorine

70
Q

what is iodine as a chemical agent?

A

a skin antiseptic

71
Q

what is the mechanism of iodine halogens as chemical agents?

A

oxidize cell constituents and iodinates proteins

72
Q

under what conditions might iodine halogen chemical agents kill endospores?

A

at high concentrations

73
Q

what are 3 drawbacks to iodine halogen chemical agents?

A
  1. skin damage
  2. skin staining
  3. allergies to iodine exist
74
Q

how is iodaphor, an iodine halogen chemical agent, usually mixed for use?

A

iodine is complexed with an organic carrier, and is realeased slowly to minimize skin burns

75
Q

what is the mechanism of chlorine halogen chemical agents?

A

oxidizes cell constituents

76
Q

in what 3 situations are chlorine halogens used as chemical agents?

A
  1. disinfection of water supplies and swimming pools
  2. dairy and food industries
  3. effective household disinfectants
77
Q

what 3 mircoorganism types do chlorine halogen chemical agents destroy?

A
  1. vegetative bacteria
  2. fungi
  3. spores
78
Q

what does specifically chlorine GAS destroy?

A

sporicidal!!

79
Q

why are chlorine halogen chemical agents not antispetics?

A

they can irritate skin

80
Q

describe use of heavy metals as chemical agents (pro and con)

A

super effective but usually toxic

81
Q

give examples of 5 heavy metals used as chemical agents

A
  1. mercury ions
  2. silver ions
  3. arsenic ions
  4. zinc ions
  5. copper ions
82
Q

what is the mechanism of heavy metals as chemical agents?

A

combine with and inactivate proteins, may also precipitate cell proteins

83
Q

what are quarternary ammonium compound chemical agents? (2)

A
  1. detergents that have broad spectrum antimicrobial activity and are effective disinfectants
  2. amphipathic organic cleansing agents
84
Q

what type of quarternary ammonium compound chemical agents are effective disinfectants? (a type of ion)

A

cation detergents

85
Q

describe cationic detergents (quarternary ammonium compounds) (2)

A
  1. kill most bacteria

2. stable and nontoxic

86
Q

what do cationic detergents (quartenary ammonium compounds) NOT kill? (2)

A
  1. M. tuberculosis

2. endospores

87
Q

what 2 things inactivate cationic detergents (quarternary ammonium compounds)?

A
  1. hard water

2. soap

88
Q

describe aldehyde chemical agents in terms of reactivity

A

highly reactive molecules

89
Q

what are 2 commonly used aldehyde chemical agents?

A
  1. formaldehyde

2. glutaraldehyde

90
Q

describe 2 things that aldehyde chemical agents are great for

A
  1. sporicidal!

2. chemical sterilants

91
Q

what are sterilizing gas chemical agents used for?

A

used to sterilize heat-sensitive materials

92
Q

what 2 -cidal things are sterilizing gas chemical agents?

A
  1. microbicidal

2. sporicidal!

93
Q

what are the 2 methods of sterilizing gas chemical agents?

A
  1. ethylene oxide sterilization carried out in equipment resembling an autoclave
  2. vaporized hydrogen peroxide can also be used in this equipment
94
Q

what 2 precautions need to be kept in mind when using sterilizing gas chemical agents?

A
  1. gases are toxic

2. gases are also flammable

95
Q

describe the field of using biological agents as a means of control of microorganisms

A

an emerging field showing great promise

96
Q

what are the 3 natural control biological agents?

A
  1. predation by Bdellovibrio
  2. viral-mediated lysis using pathogen specific bacteriophage lysins (or bacteriophages themselves)
  3. toxin-mediated killing using bacteriocins
97
Q

describe new FDA news regarding use of bacteriophage biological control mechanisms

A

a spray format of using bacteriophages themselves was just approved to use on meat carcasses

98
Q

what is the drawback of using biological control mechanisms?

A

they all work on only one specific microorganism each; this highly specialized nature means there is no way to make a broad spectrum form, and requires extensive culturing or testing to ensure the proper targt is chosen to actually have an impact

99
Q

who evaluates the effectiveness of disinfectants?

A

EPA (environmental protection agency)

100
Q

who evaluates the effectiveness of agens used on humans and animals?

101
Q

what are the 6 conditions that influence the effectiveness of antimicrobial agent activity?

A
  1. population size
  2. population composition
  3. concentration or intensity of an antimicrobial agent
  4. contact time
  5. temperature
  6. local environment
102
Q

describe population size as an influence on the effectiveness of antimicrobial agent activity

A

larger populations take longer to killthan smaller populations

103
Q

describe population composition as an influence on the effectiveness of antimicrobial agent activity

A

microorganisms differ markeldy in their sensitivity to antimicrobial agents

104
Q

describe concentration or intensity of an antimicrobial agent as an influence on the effectiveness of antimicrobial agent activity (2)

A
  1. usually higher concentrations of an agent kill more rapidly
  2. but the relationship is not linear, microbes are sneaky
105
Q

describe contact time as an influence on the effectiveness of antimicrobial agent activity

A

the longer the exposure, the more organisms killed

106
Q

describe temperature as an influence on the effectiveness of antimicrobial agent activity

A

higher temperatures enhance chemical activity (usually making agent more effective)

107
Q

describe local environment as an influence on the effectiveness of antimicrobial agent activity (2)

A
  1. pH, viscosity, concentration of organic matter, and other things can profoundly impact effectiveness of an agent
  2. organisms in biofilms are less susceptible to many antimicrobial agents

Veterinary Microbiology (11 decks)

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