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PH151 Lab > Chapter 4 > Flashcards

Chapter 4 Flashcards

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1
Q

Killing or removal of ALL viable organisms in an object or habitat

A

Sterilization

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2
Q

Killing, inhibition or removal of microorganisms that may cause disease

A

Disinfection

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3
Q

Agents used to carry out disinfection and are normally used only on inanimate objects

A

Disinfectants

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4
Q

Reduction of microbial population to levels considered safe by public health standards

A

Sanitization

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5
Q

Prevention of infection or sepsis in living tissue using chemicals

A

Antisepsis

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6
Q

Agents used to carry out antisepsis but generally not as toxic as disinfectants; can be used on living tissue

A

Antiseptics

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7
Q

Introduced use of phenol (carbolic acid) during surgeries and for wound dressings

A

Lister

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8
Q

Microbial Control

A

Inhibition of growth

Destruction of the organism

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9
Q

Why do we control microorganisms

A

To prevent spoilage of valuable substances
To prevent infection
To prevent contamination of cultures, person, and environment

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10
Q

Agents used in microbial control

A

Physical agents

Chemical agents

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11
Q

Physical agents

A 
Heat
Low temperature
Filtration
Desiccation
Increased osmotic pressure
Radiation
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12
Q

Examples of moist heat

A

Boiling or flowing steam
Pasteurization
Steam under pressure
Tyndallization

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13
Q

Kills vegetative cells and eukaryotic spores within 10 minutes

A

Boiling or flowing steam

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14
Q

Process that uses brief exposure and high temperature to reduce microbial population and eliminate human pathogens

A

Pasteurization

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15
Q

Basis of pasteurization

A

Coxialla burnettii

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16
Q

LTH in pastuerization

A

62.8C , 30 minutes

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17
Q

HTST in pasteurization

A

72C , 15 seconds

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18
Q

UHT in pastuerization

A

140C to 150C , 1-2secs

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19
Q

Uses autoclave or pressure cooker

121C , 15 mins

A

Steam under pressure

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20
Q

Basis for steam under pressure

A

Bacillus stearothermophilus

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21
Q

3 successive days
90C to 100C for 30-60 mins
Incubation at 37C in between days

A

Tyndallization

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22
Q

Another name for Tyndallization

A

Fractional steam sterilization

Intermittent sterilization

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23
Q

Examples of dry heat

A

Direct flame

Hot air

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24
Q

Uses bunsen burner or alcohol lamp

A

Direct flame

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25
Another name for direct flame
Incineration
26
Uses mechanical convection oven | 170C to 180C for 1 hour
Hot air
27
Limits growth due to decreased rate of cell reactions
Low temperature
28
Temp at 4C
Refrigeration
29
Temp at 0C to -95C
Freezing or deep-freezing
30
Exclusion of microorganisms | For heat-sensitive materials
Filtration
31
Removes 99.97% micrometer particles
HEPA filter
32
Microbiostasis - drying - freeze-drying
Desiccation
33
Microbiostasis Increase solute concentration (by adding sugar, salt)
Increased osmotic pressure
34
Types of radiation
Ionizing radiation | Non-ionizing radiation
35
Results in DNA destruction Cause atoms to lose electrons or ionize Excellent sterilizing agent
Ionizing radiation
36
Example of ionizing radiation
X-rays | Gamma rays
37
Formation of thymine dimers | Surface sterilization only
Non-ionizing radiation
38
Non-ionizing radiation is most lethal at ___ which results to ____
260nm | DNA damage
39
Chemicals that kill microorganisms or prevent growth or prevent growth
Antimicrobial agents
40
Substances that kill organisms
-cide
41
Substances that prevent growth of organisms
-static
42
Examples of chemical agents
``` Germicide Bactericide Fungicide Algicide Fungistat Bacteriostat ```
43
Disruption of plasma membrane Protein denaturation Inactivation of enzymes
Phenols | Phenolics
44
Commonly used in soaps, shampoos, depdorants, etc.
Phenolic compounds | - triclosan/triclocarbon, hexachlorophene
45
Denature proteins | Dissolve membrane lipids
Alcohols | - ethanol and isopropanol
46
Oxidation of cell constituents | Also inhibit protein function
Halogens | - chlorine, iodine
47
Denatures enzymes and other essential proteins
Heavy metals | - silver, copper, mercury
48
Prevents ophthalmic gonorrhea
1% silver nitrate
49
Used on burns
Silver sulfadiazine
50
Algicide
Copper sulfate
51
Disinfects skin mucous membrane
Merthiolate
52
Mechanical removal or microorganisms
Surfactants | - soaps and acid anionic detergents
53
Disrupts plasma membrane and denature protein
Surfactants | - cationic detergents and quaternary ammonium compounds
54
Used in food and cosmetics
Organic acids | - sorbic acid, propionic acid, etc.
55
Protein denaturation Used on heat-sensitive items Rapidly penetrate packing materials Microbicidal and sporicidal
Sterilizing Gases | - ethylene oxide
56
Protein inactivation | Chemical sterilants
Aldehydes | - formalin, glutaraldehyde
57
Oxidation of cell components
Oxidizing agents | - hydrogen peroxide
58
Conditions influencing effectiveness of antimicrobial agent activity
``` Population size Population composition Concentration or intensity of product Duration of exposure Temperature Local environment ```
59
Points to remember
Few chemical agents achieve sterility | Spectrum of susceptibility of microorganisms
60
Factors affecting growth
``` Temperature Nutrients Moisture Aeration pH ```
61
Phases of microbial growth
Lag phase Log phase Stationary phase Death phase
62
Adaptation phase Occurs upon initial transfer No increase in cell mass/number Synthesis of protoplasm
Lag phase
63
Cells are dividing steadily at a constant rate Growth rate is at its maximum Cells are mostly uniform
Log phase
64
Growth rate tapers off - exhaustion of nutrients - accumulation of waste Growth = Death
Stationary phase
65
Death rate > growth rate Decline in the # of viable cells Nutrient depletion Further accumulation of wastes
Death phase
66
Reproduction
Multicellular - spores Unicellular - binary fission
67
Measurement of Growth
Standard Plate Growth Direct Count Turbidimetric Method
68
Most common method used | Usually indirectly done through serial dilution and plating
Standard plate count
69
Advantage and Disadvantage of SPC
A: can determine # of living cells D: underestimation of cell population
70
Both viable and non-viable cells are counted | Utilizes counting chamber microscope
Direct count
71
Indirectly measures cell mass (the more turbid; the higher the cell mass) Utilizes a spectrophotometer
Turbidimetric method

PH151 Lab (5 decks)

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