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MICROBIOLOGY!225-80 > Chap 7 > Flashcards

Chap 7 Flashcards

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Biology 101 flashcards
1
Q

Sepsis

A

refers to bacterial contamination

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2
Q

Asepsis

A

absence of significant contamination

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3
Q

Aseptic surgery techniques

A

prevent the microbial contamination of wounds

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4
Q

Sterilization

A

removing and destroying all microbial life

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5
Q

Commercial sterilization

A

killing Clostridium botulinum endospores from canned goods

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6
Q

Disinfection

A

destroying harmful microorganisms

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7
Q

Antisepsis

A

destroying harmful microorganisms from living tissue

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8
Q

Degerming

A

the mechanical removal of microbes from a limited area

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9
Q

Sanitization

A

lowering microbial counts on eating utensils to safe levels

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10
Q

Biocide (germicide):

A

treatments that kill microbes

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11
Q

Bacteriostasis:

A

inhibiting, not killing, microbes

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12
Q

The usual definition of sterilization is the removal or destruction of all forms of microbial life; how could there be practical exceptions to this simple definition?

A

Disinfectants and Antiseptics do not kill or remove all bacteria and viruses. Prions and endospores have a high resistance to all forms of sterilization; sterilization implies to the absence of prions.

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13
Q

Effectiveness of treatment depends on

A
  1. Number of microbes
  2. Environment (organic matter, temperature, biofilms)
  3. Time of exposure
  4. Microbial characteristics
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14
Q

If the rate of killing is the same, how long will it take to kill all the members of a larger population compared to a smaller population

A

It will take longer to kill all members of a larger population than a smaller population

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15
Q

How is it possible that a solution containing a million bacteria would take longer to sterilize than one containing a half-million bacteria?

A

A larger number of bacteria will require more time to be completely killed, as the process of sterilization is a slow one.

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16
Q

Actions of Microbial Control Agents

A
  1. Alteration of membrane permeability
  2. Damage to proteins (enzymes)
  3. Damage to nucleic acids
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17
Q

Would a chemical microbial control agent that affects plasma membranes affect humans?

A

A microbial agent that targets the plasma membrane of the microorganism would not be advised because humans also have a plasma membrane.

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18
Q

Thermal death point (T D P):

A

lowest temperature at which all cells in a liquid culture are killed in 10 min

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19
Q

Thermal death time (T D T):

A

minimal time for all bacteria in a liquid culture to be killed at a particular temperature

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20
Q

Decimal reduction time (D R T)

A

Minutes to kill 90% of a specific population of bacteria at a given temperature

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21
Q

What does moist heat sterilization do?

A

Moist heat coagulates/denatures proteins

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22
Q

Moist heat sterilization involves

A
  1. Boiling
  2. Free-flowing steam
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23
Q

Autoclave

A

steam under pressure

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24
Q

How does autoclave sterilization work?

A
  1. 121 C at 15 psi for 15 min
    2.Kills all organisms and endospores
  2. Steam must contact the item’s surface
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25
Q

In moist heat sterilization, large containers require

A

longer sterilization times

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26
Q

What is used to indicate sterility in moist heat sterilization?

A

Test strips

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27
Q

Why are containers only filled to 75% of their capacity in an autoclave?

A

Liquids boil vigorously

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28
Q

Pasteurization

A

reduces spoilage organisms and pathogens

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29
Q

High-temperature short-time (HTST)

A

72 C for 15 sec

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30
Q

Thermoduric organisms

A

survive heat

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31
Q

Dry heat sterilization kills by

A

oxidation

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32
Q

Examples of dry heat sterilization

A

Flaming
Incineration
Hot-air sterilization

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33
Q

Filtration

A

Passage of substance through a screenlike material

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34
Q

Filtration is used for

A

heat-sensitive materials

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35
Q

High-efficiency particulate air (H E P A) filters remove

A

microbes > 0.3 micrometers in diameter

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36
Q

Membrane filters remove

A

microbes > 0.22 micrometers

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37
Q

Membrane filters with pore sizes as small as 0.01 micrometers can filter out

A

viruses and large proteins

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38
Q

Physical methods of microbial control

A
  1. Low temp
  2. High pressure
  3. Dessication
  4. Osmotic pressure
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39
Q

Examples of low temperature having a bacteriostatic effect

A

Refrigeration
Deep-freezing
Lyophilization (freeze drying)

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40
Q

High pressure denatures

A

proteins

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41
Q

Desiccation

A

absence of water prevents metabolism

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42
Q

how does osmotic pressure help control microbes?

A

uses high concentrations of salts and sugars to create hypertonic environment; causes plasmolysis

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43
Q

Plasmolysis

A

shrinkage of the protoplasm of a plant cell and is caused due to the loss of water in the cell

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44
Q

protoplasm

A

the colorless material comprising the living part of a cell, including the cytoplasm, nucleus, and other organelles.

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45
Q

Ionizing radiation examples

A

(X - rays, gamma rays, electron beams)

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46
Q

How does ionizing radiation inhibit microbial growth?

A
  1. Ionizes water to create reactive hydroxyl radicals
  2. Damages D N A by causing lethal mutations
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47
Q

Nonionizing radiation

A

ultraviolet, 260 nm

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48
Q

How does non-ionizing radiation control microbial growth?

A

Damages D N A by creating thymine dimers

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49
Q

How do microwaves affect microbes?

A

kill by heat; not especially antimicrobial

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50
Q

How is microbial growth in canned foods prevented?

A

using heat and creating a vacuum to destroy microorganisms and prevent recontamination

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51
Q

Why would a can of pork take longer to sterilize at a given temperature than a can of soup that also contained pieces of pork?

A

Solid foods heat unevenly because of the uneven distribution of moisture.

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52
Q
A
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53
Q

What is the connection between the killing effect of radiation and hydroxyl radical forms of oxygen?

A

These radicals are produced from ionizing radiation that take electrons from other molecules.

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54
Q

4 Principles of Effective Disinfection

A

1.Concentration of disinfectant
2.Organic matter
3.p H
4.Time

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55
Q

What is a Use-Dilution test?

A

minimal inhibitory concentration of an antimicrobial to inhibit or kill the bacteria/fungi

a laboratory method used to assess the effectiveness of a liquid disinfectant on hard, nonporous surfaces by exposing a standardized test carrier (like a stainless steel cylinder) coated with a known bacteria to a specific dilution of the disinfectant for a set time, then checking if the bacteria are still viable after incubation

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56
Q

Explain the process of Use-Dilution Tests

A
  1. Metal cylinders are dipped in test bacteria and dried
  2. Cylinders are placed in disinfectant for 10 min at 20 C
  3. Cylinders are transferred to culture media to see if bacteria survived treatment.
57
Q

Disk-Diffusion Method is used to

A

Evaluates efficacy of chemical agents

58
Q

How does the disk diffusion method work?

A
  1. Filter paper disks are soaked in a chemical and placed on a culture
  2. Look for zone of inhibition around disks
59
Q

If you wanted to disinfect a surface contaminated by vomit and a surface contaminated by a sneeze, why would your choice of disinfectant make a difference?

A

vomit typically contains a wider variety of microorganisms, including bacteria, viruses, and parasites, which might require a disinfectant with a broader spectrum of killing power, while a sneeze usually contains primarily viruses and some bacteria, potentially allowing for a more targeted disinfectant depending on the suspected pathogen.

60
Q

Which is more likely to be used in a medical clinic laboratory, a use-dilution test, or a disk-diffusion test?

A

the disk-diffusion test is the standard method for determining a bacteria’s susceptibility to antibiotics, which is a crucial aspect of patient care in a clinical setting.

61
Q

Phenol and phenolics injure

A

lipids of plasma membranes, causing leakage

62
Q

Bisphenols are made of

A

two phenol groups connected by a bridge

63
Q

The two phenols connected by a bridge in bisphenols are

A

Hexachlorophene and triclosan

64
Q

Function of bisphenols

A

Disrupt plasma membranes

65
Q

What are biguanides?

A

a class of oral medications that help control blood sugar levels, and include metformin

66
Q

Chlorhexidine is a type of

A

Biguanide

67
Q

Chlorhexidine and biguanides are used in

A

surgical hand scrubs; can clean the skin after an injury, before surgery, or before an injection.

68
Q

what do biguanides do?

A

Disrupt plasma membranes

69
Q

What are essential oils

A

Mixtures of hydrocarbons extracted from plants
Peppermint oil, pine oil, orange oil

70
Q

uses of essential oils

A

Used for centuries in traditional medicine and for preserving food

71
Q

What causes the microbial action in essential oils?

A

primarily due to phenolics and terpenes

72
Q

Essential oils have stronger activity against

A

gram-positive bacteria; effectiveness against viruses not studied to date

73
Q

How does iodine affect microbes

A

Impairs protein synthesis and alters membranes

74
Q

Iodine tincture

A

solution in aqueous alcohol

75
Q

Iodophor

A

Iodine combined with organic molecules

76
Q

How does chlorine affect microbes?

A

Oxidizing agents; shut down cellular enzyme systems

77
Q

Bleach

A

hypochlorous acid (H O C l)

78
Q

Chloramine

A

chlorine + ammonia

79
Q

What do alcohols do to microbes?

A

Denatures proteins and dissolves lipids

80
Q

Alcohols have no effect on

A

endospores and nonenveloped viruses

81
Q

Ethanol and isopropanol require

A

water

82
Q

Oligodynamic action of heavy metals and their compounds

A

very small amounts exert antimicrobial activity

83
Q

What do heavy metals and their compounds to to microbes?

A

Denature proteins

84
Q

Heavy metals and their compounds

A

Ag, Hg, Cu, Zn

85
Q

Silver nitrate is used to prevent

A

ophthalmia neonatorum

86
Q

Mercuric chloride prevents

A

mildew in paint

87
Q

Copper sulfate is an

A

algicide

88
Q

Zinc chloride is found in

A

mouthwash

89
Q

soap

A

Degerming; emulsification

90
Q

Acid-anionic sanitizers

A

Anions react with the plasma membrane

91
Q

Quarternary ammonium compounds quats

A

Cations are bactericidal, denature proteins, disrupt plasma membrane

92
Q

Sulfur dioxide prevents

A

wine spoilage

93
Q

organic acids inhibit

A

metabolism

94
Q

Sorbic acid, benzoic acid, and calcium propionate prevent

A

molds in acidic foods

95
Q

Nitrites and nitrates prevent

A

endospore germination

96
Q

What are Bacteriocinsproteins?

A

proteins or peptides produced by bacteria that can kill or inhibit the growth of other bacteria

97
Q

Nisin and natamycin (pimaricin) prevent spoilage of

A

cheese

98
Q

Examples of antibiotics

A

nisin, natamycin, bacteriocinsproteins

99
Q

How do aldehydes prevent microbial activity?

A

Inactivate proteins by cross-linking with functional groups

100
Q

When are aldehydes used?

A

preserving specimens and in medical equipment
Formaldehyde and ortho-phthalaldehyde
Glutaraldehyde is one of the few liquid chemical sterilizing agents

101
Q

one of the few liquid chemical sterilizing agents

A

Glutaraldehyde

102
Q

How does chemical sterilization work?

A

Gaseous sterilants cause alkylation-replacing hydrogen atoms of a chemical group with a free radical

103
Q

what sterilization technique Cross-links nucleic acids and proteins?

A

Chemical sterilization

104
Q

What is used to sterilize heat-sensitive material?

A

Ethylene oxide

105
Q

Plasma

A

Fourth state of matter, consisting of electrically excited gas

106
Q

How does plasma help sterilize?

A

Free radicals destroy microbes

107
Q

Plasma sterilization is used for what kind of instruments?

A

Tubular instruments

108
Q

What are supercritical fluids?

A

CO2 with gaseous and liquid properties

109
Q

What are supercritical fluids used to sterilize?

A

medical implants

110
Q

Peroxygens and Other Forms of Oxygen are what kind of agents?

A

oxidizing agents

111
Q

Peroxygens and Other Forms of Oxygenare used to sterilize

A

contaminated surfaces and food packaging

112
Q

Examples of Peroxygens and Other Forms of Oxygen

A

O3, H2O2, and peracetic acid

113
Q

Why is alcohol effective against some viruses and not others?

A

Enveloped viruses have a lipid membrane, while nonenveloped viruses are those without a lipid membrane. Generally, nonenveloped viruses are more resistant to disinfectants. Isopropyl alcohol works against enveloped viruses but not against nonenveloped viruses.

114
Q

Is Betadine an antiseptic or a disinfectant when it is used on skin?

A

Yes, Betadine is both an antiseptic and a disinfectant when used on skin:

  1. Antiseptic: Betadine prevents the growth of bacteria that cause infections.
  2. Disinfectant: Betadine kills bacteria, fungi, and viruses on the skin by damaging their proteins
115
Q

What characteristics make surface-active agents attractive to the dairy industry?

A

Acid-Anionic Sanitizers: important in cleaning dairy utensils and equipment; Non-toxic; non-corrosive; and fast acting.

116
Q

What chemical disinfectants can be considered sporicides?

A

PGBEP
1.Phenols; 2.Glutaraldehyde; 3.B-Propiolactone;
4.Ethylene oxide ;
5.Peroxy acids.

117
Q

What chemicals are used to sterilize?

A

Alcohol.
Chlorine and Chlorine Compounds.
Formaldehyde.
Glutaraldehyde.
Hydrogen Peroxide.
Iodophors.
Ortho-phthalaldehyde (OPA)
Peracetic Acid.

118
Q

Effect against endospores Glutaraldehyde

A

Fair

119
Q

Effect against endospores chlorines

A

Fair

120
Q

Effect against endospores alcohols

A

poor

121
Q

Effect against endospores iodine

A

poor

122
Q

Effect against endospores phenolics

A

poor

123
Q

Effect against endospores chlorhexidine

A

none

124
Q

Effect against endospores bisphenols

A

none

125
Q

Effect against endospores quats

A

none

126
Q

Effect against endospores silver

A

none

127
Q

Effect against mycobacteria Glutaraldehyde

A

Good

128
Q

Effect against mycobacteria chlorines

A

Fair

129
Q

Effect against mycobacteria alcohols

A

Good

130
Q

Effect against mycobacteria Iodine

A

Good

131
Q

Effect against mycobacteria Phenolics

A

Good

132
Q

Effect against mycobacteria Chlorhexidine

A

Fair

133
Q

Effect against mycobacteria Bisphenols

A

None

134
Q

Effect against mycobacteria Quats

A

none

135
Q

Effect against mycobacteria Silver

A

none

136
Q

The presence or absence of endospores has an obvious effect on microbial control, but why are gram-negative bacteria more resistant to chemical biocides than gram-positive bacteria?

A

Gram-negative bacteria are generally more resistant to chemical biocides than gram-positive bacteria because they possess an outer membrane, which acts as a protective barrier, preventing many chemicals from easily penetrating the cell and reaching their target sites within the bacteria;

137
Q
A
138
Q

Gaseous sterilants cause alkylation-

A

replacing hydrogen atoms of a chemical group with a free radical

MICROBIOLOGY!225-80 (24 decks)

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