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BACT 211 > P1 | Sterilization and Disinfection (LECTURE) > Flashcards

P1 | Sterilization and Disinfection (LECTURE) Flashcards

1
Q

Refers to the destruction of all forms of life, including bacterial spores

  • Originated more than 100 years ago
  • Complete removal of microorganisms including spores
  • “All or nothing” process
A

Sterilization

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2
Q

What methods are used in Sterilization?

A
  • Physical method
  • Chemical method
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3
Q

Refers to a process that eliminates a defined scope of microorganisms, including some spores

  • Reduces the number of microorganisms
  • Physical or chemical methods may be used, but most disinfectants are chemical agents applied to inanimate objects
A

Disinfection

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4
Q

Substance applied to the skin for the purpose of eliminating or reducing the number of bacteria present

Do not kill spores and cannot be used as disinfectants

  • destroy/inhibit the growth of microorganisms
  • Joseph Lister used:
A

Antiseptic

E.g., Alcohol

  • Carbolic acid
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5
Q

Factors that Affect the Degree of Killing of Microorganisms

(T.O, N.O, C.D.A, P.O.M, N.S.D, C.T, T, pH, BF, CoD)

A
  1. Types of Organisms
  2. Number of Organisms
  3. Concentration of Disinfecting Agent
  4. Presence of Organic Material
  5. Nature of Surface to be Disinfected
  6. Contact Time
  7. Temperature
  8. pH
  9. Biofilms
  10. Compatibility of Disinfectants
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6
Q

Different organisms have varying ability in withstanding and chemical and physical treatment due to the different biochemical composition of these organisms and various mechanisms that they use to protect themselves

A

Types of Organisms

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7
Q

Types of Organisms

(SFB, MB spp., BFB, P)

A
  1. Spore forming Bacteria
  2. Mycobacterium spp.
  3. Biofilm forming Bacteria
  4. Prions
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8
Q

Types of Organisms

Spores are coated with proteins, lipids and carbohydrates as well as dipicolinic acid calcium

SFB

  • able to resist heat
A

Spore forming Bacteria

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9
Q

Types of Organisms

cell wall is high in lipid which enables them to become resistant to most environmental stress such as desiccation

MB spp.

A

Mycobacterium spp.

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10
Q

Types of Organisms

certain bacteria can aggregate into communities of bacteria which makes then resistant to chemical and physical means of destruction

(BFB)

A

Biofilm forming Bacteria

  • Biofilm: microorganism living in community
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11
Q

Types of Organisms

naked pieces of proteins, similar to viruses but without the nucleic acid, that is most resistant to the action of heat, radiation, and chemicals

  • agent able to cause the generative diseases of our nervous system
A

Prions

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12
Q

this factor basically refers to the amounts of organisms present in the object to be treated referred to as microbial load (bioburden)

  • the higher the number of organisms, the longer the exposure time needed to eliminate 99.9% of the microorganisms
A

Number of Organisms

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13
Q

The amount needed to destroy microorganisms varies based on the agent to be used.

concentrated agents do not necessarily mean that it would work better

  • It is therefore important to follow, the correct preparation and dilution as prescribed by the manufacturer.
  • 1:10 bleach (common disinfectant)
A

Concentration of Disinfecting Agent

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14
Q

Blood, puss, and mucus are examples of organic materials that may prevent the full contact of the agent to the organisms, hence limiting its action

POM

  • Example: is bleach (sodium hypochlorite) that is easily inactivated by organic material.
A

Presence of Organic Material

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15
Q

Some instrument that we use in the laboratory sometimes are made up of biomaterial which exempts them to disinfection or sterilization due to possible damage

NSD

  • Example: is endoscopic instruments which can’t be autoclaved
A

Nature of Surface to be Disinfected

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16
Q

It is critical to observe proper (___) of the agent and the object to be disinfected or sterilized.

  • In principle, (____) may be affected by all previous factors already mentioned as well as temperature
A

Contact Time

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17
Q

Alcohol and betadine has to be in contact for about (____) to work properly

A

1-2 minutes

  • Spore forms may need more contact time than its vegetative counterpart
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18
Q

their activity may increase at a certain degree by a corresponding increase in temperature or may decrease when temperature is decreased

A

Temperature

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19
Q

Temperature

disinfectants are usually used at room temperature (____)

A

20C to 220C

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20
Q

Temperature

Too high or low temperature may?

A

inactivate disinfectants and sterilants

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21
Q

It is also important to consider the (____) of the material to be treated and he agent itself.

  • Manufacturers usually optimize this factor to achieve maximum activity
A

pH

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22
Q

Certain bacteria have to ability to form communities of layers of bacteria with protective shield which is called as?

  • community of bacteria
  • Inanimate and animate objects
A

Biofilms

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23
Q

It is important to consider that (____) formation may require longer contact time or increase in the concentration of the agent

  • E.g., Hospital – Catheter (lots of bacteria)
A

Biofilm

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24
Q

Some disinfectants may inactivate the action of another hence it is also important to consider the (____)

  • bleach and quaternary ammonium compounds which may negate each other
A

Compatibility of Disinfectants

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25
Q

METHODS OF STERILIZATION

A

Physical methods:
* Moist Heat
* Dry Heat
* Ionizing Radiation
* Filtration
Chemical Methods:
* Peracetic Acid
* Formaldehyde Vapor/ Vapor Phase H2O2
* Glutaraldehyde
* Ethylene Oxide (ETO) Gas

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26
Q

Physical Methods

coagulation of bacterial proteins including bacterial enzymes

A

Moist Heat

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27
Q

Simplest means of sterilizing a material:

A

Heat

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28
Q

Types of moist heat:

A.T.I

A
  • Autoclave
  • Tyndallization
  • Inspissation
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29
Q

Physical Methods: moist heat

operates based on the principle of steam under pressure

A

Autoclave

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30
Q

Physical Methods: moist heat

Effective indication:
* Sterilization:
* Decontamination:
* Biological indicator:

Autoclave

A
  • 121C to 15lbs/ in2 for 15 minutes
  • 135C for 30lbs in2 for 30 minutes
  • Bacillus stearothermophilus
31
Q

Physical Methods: moist heat

fractional discontinuous sterilization

A

Tyndallization

32
Q

Physical Methods: moist heat

  • Effective indication:
  • Instrument:

Tyndallization

A
  • 100C for 30-60 minutes
  • Arnold’s Sterilizer
33
Q

Physical Methods: moist heat

thickening through evaporation

A

Inspissation

34
Q

Physical Methods: moist heat

  • Effective indication:
  • Instrument:

Inspissation

A
  • 75C to 80C for 2 hours
  • Inspissator
35
Q

Control of Microorganisms using Heat Methods

BW(S), AC (SUP), PBM, PFM, O (DH)

A

Methods:
* Boiling Water (steam)
* Autoclave (steam under pressure)
* Pasteurization Batch Method
* Pasteurization Flash Method
* Over (Dry Heat)

36
Q

Control of Microorganisms using Heat Methods

  • Boiling Water (steam)
  • Autoclave (steam under pressure)
  • Pasteurization Batch Method
  • Pasteurization Flash Method
  • Over (Dry Heat)

Temperature

A
  • 100 C
  • 121.6 C
  • 63 C
  • 72 C
  • 160-180 C

Temperature

37
Q

Control of Microorganisms using Heat Methods

  • Boiling Water (steam)
  • Autoclave (steam under pressure)
  • Pasteurization Batch Method
  • Pasteurization Flash Method
  • Over (Dry Heat)

Time required

A
  • 15min
  • 15min at 15psi
  • 30min
  • 15s
  • 1.5-3hrs

Time required

38
Q

Control of Microorganisms using Heat Methods

  • Boiling Water (steam)
  • Autoclave (steam under pressure)
  • Pasteurization Batch Method
  • Pasteurization Flash Method
  • Over (Dry Heat)

Applications

A
  • Kills microbial vegetative forms; endospores survive
  • Sterilizes and kills endospores
  • Disinfects and kills milk-borne pathogen and vegetable forms; endospores survive
  • Same, but shorter time at higher temp.
  • Sterilizes; keeps materials dry

Applications

39
Q

METHODS OF STERILIZATION: Physical Methods

oxidation of bacterial components

DH

  • requires longer exposure time
A

Dry Heat

40
Q

Physical Methods: Dry heat

direct application of flame in aseptic technique

A

Direct Flame

41
Q

Physical Methods: Dry heat

used in the sterilization of heat resistant materials

A

Dry/Hot Air Oven

42
Q

Physical Methods: Dry heat

  • Effective indication:
  • Biological indicator:

Dry/Hot Air Oven

A
  • 160-180C for 1.5 to 2 hours
  • Bacillus subtilis var. niger
43
Q

Physical Methods: Dry heat

burns materials into ashes; used in the disposable of biological wastes

A

Incineration

44
Q

Physical Methods: Dry heat

  • Effective indication:

Incineration

A
  • 870-980C for 2 seconds
45
Q

Physical Methods

works by alkylation of nucleic acid of bacteria using high energy short wavelength deep penetrating gamma rays; used for heat sensitive materials

  • sterilization of recycled materials
A

Ionizing Radiation

46
Q

Physical Methods: Ionizing Radiation

  • Biological indicator:
A
  • Bacillus pumilis
47
Q

Physical Methods

  • Based on membrane gradient by differences in particle size
  • Used for the sterilization of heat sensitive materials
A

Filtration

48
Q

Physical Methods: Filtration

Types of Filtration:

A
  • Water/ Liquid Solutions/ Antibiotics/ Vaccines
  • Air: High Efficiency Particulate Air Filter (HEPA)
49
Q

Physical Methods: Filtration

usually uses a thin membrane filter of cellulose acetate with different pore size depending on the intended purpose

A

Water/ Liquid Solutions/ Antibiotics/ Vaccines

50
Q

Physical Methods: Filtration

most bacteria, yeasts, and molds are retained but may allow passage of Pseudomonas- like organisms

Water/ Liquid Solutions/ Antibiotics/ Vaccines

(size)

A

0.45 – 0.80um

51
Q

Physical Methods: Filtration

used to filter Pseudomonas- like organisms; used for critical sterilization of parenteral solutions

Water/ Liquid Solutions/ Antibiotics/ Vaccines

(size)

A

0.22um

52
Q

Physical Methods: Filtration

able to retain small viruses

Water/ Liquid Solutions/ Antibiotics/ Vaccines

(size)

A

0.01um

53
Q

Physical Methods: Filtration

Has a pore size of 0.3 μm; usually used in Biological Safety Cabinet (BSC) and rooms of immunocompromised patients

A

Air: High Efficiency Particulate Air Filter (HEPA)

54
Q

Chemical Methods

for surgical instruments

A

Peracetic Acid

55
Q

Chemical Methods

for HEPA filters and large spaces

A

Formaldehyde Vapor/ Vapor Phase H2O2

56
Q

Chemical Methods

for medical instruments (e.g., bronchoscopes, etc.)

A

Glutaraldehyde

57
Q

Chemical Methods

This method is also used extensively by the manufacturing industry for the sterilization of low-cost thermoplastic products

  • For large spaces and spaceships and other heat sensitive materials
A

Ethylene Oxide (ETO) Gas

58
Q

Chemical Methods: Ethylene Oxide (ETO) Gas

  • The recommended concentration of ethylene
    oxide is (____)
  • per liter of chamber space at (____)
A
  • 450 to 700mg
  • 55C to 60C for 2 hours
59
Q

Chemical Methods: Ethylene Oxide (ETO) Gas

  • Biological indicator:
A
  • Bacillus subtilis var. globijii
60
Q

METHODS OF DISINFECTION

A

Physical Methods
* Boiling
* Pasteurization
* Non-Ionizing Radiation

Chemical Methods
* Alcohol
* Halogens
* Heavy Metals
* Quaternary Ammonium Compounds (QUATS)
* Phenol/Phenolic Compounds/Bisphenols

61
Q

Physical Methods

Destroys vegetative cells of bacteria but not their spores

A

Boiling

62
Q

Physical Methods: Boiling

  • Effective indication:
A
  • 100C for 15-30 minutes
63
Q

Physical Methods

Used for the preservation of alcoholic beverages such as beers, wines, and also dairy products such as milks and yogurt

A

Pasteurization

64
Q

Physical Methods: Pasteurization

  • Batch:
  • Flash:
  • Ultra-High Temperature (UHT):
A
  • 62.5C for 30 minutes
  • 72C for 15 seconds
  • 72C to 110C for 5 seconds
65
Q

Physical Methods

Uses low energy long wavelength ultraviolet rays to disinfect heat sensitive materials as well as large spaces

A

Non-Ionizing Radiation

66
Q

Chemical Methods: Alcohol

  • MOA:
  • Minimum Contact Time:

  • 70% Alcohol not 90%
  • Ethyl and Isopropyl alcohol kills (____)
A
  • Dehydration, Lipid dissolution and Protein denaturation
  • 1-2 minutes or until completely evaporated

  • Mycobacterium tuberculosis
67
Q

Chemical Methods: Halogens

  • MOA:
  • Chloride (Cl) IN NaOCl:

  • commonly used in household
A
  • inhibits protein function and acts as strong oxidizing agents
  • used as disinfecting agents in many laboratory and hospitals spaces, surfaces, and also in treating water for portability Iodine (I2) in Betadine used as a household antiseptics and surgical antiseptics

  • Sodium hydrochloride
68
Q

Chemical Methods: Heavy Metals

  • MOA:
  • Mercury (Hg):
  • Cooper (Cu):
  • Silver (Ag):
A
  • Denaturation of enzymes and other essential bacterial proteins
  • active ingredient or merthiolate but this is already banned in the market due to its known toxicity
  • CuSO4 crystals are used as algaecide in swimming pools and aquarium
  • 1% AgNO3 – used as prophylactic agent in Crede’s Prophylaxis in suspected cases of Ophthalmia neonatorum (caused by Neisseria gonorrhoeae) (replaced with erythromycin)
69
Q

Chemical Methods: Quaternary Ammonium Compounds (QUATS)

  • MOA:
  • Zephiran:
  • Cepacol:

  • enzyme inhibition, protein denaturation, and disruption of plasma membrane
A
  • enzyme inhibition, protein denaturation, and disruption of plasma membrane
  • Benzalkonium chloride
  • Cetylpyridium chloride
70
Q

Chemical Methods: Phenol/Phenolic Compounds/Bisphenols

  • MOA:

  • Germicidal soaps
A
  • Plasma membrane destruction and enzyme denaturation
71
Q

Chemical Agents Commonly used as Disinfectants and Antiseptics (SUMMARY)

TYPES:

A
  • Alcohols (50%-70%)
  • Aldehydes (in solution)
  • Halogens
  • Heavy Metals
  • Detergents
  • Phenolics
  • Gases
72
Q

Chemical Agents Commonly used as Disinfectants and Antiseptics (SUMMARY)

  • Alcohols (50%-70%)
  • Aldehydes (in solution)
  • Halogens
  • Heavy Metals
  • Detergents
  • Phenolics
  • Gases

Agent/s

A
  • Ethanol, isopropanol, benzyl alcohol
  • Formaldehyde (8%), glutaraldehyde (2%)
  • Tincture of iodine (2% in 70% alcohol) Chlorine and chlorine compounds
  • Silver nitrate (AgNO3) & Mercuric chloride (HgCl2)
  • Quaternary ammonium compounds
  • Phenol, carbolic acid, Lysol, hexachlorophene
  • Ethylene oxide
73
Q

Chemical Agents Commonly used as Disinfectants and Antiseptics (SUMMARY)

  • Alcohols (50%-70%)
  • Aldehydes (in solution)
  • Halogens
  • Heavy Metals
  • Detergents
  • Phenolics
  • Gases

Action

A
  • Denature proteins; make lipids soluble
  • React with NH2+, -SH and -COOH groups
  • (Inactive proteins) Reacts with water to
    form hypochlorous acid (HClO); oxidizing agent
  • Precipitates proteins Reacts with -SH groups; lyses cell membrane
  • Disrupt cell membranes
  • Denature proteins; disrupt cell membranes
  • Alkylating agent
74
Q

Chemical Agents Commonly used as Disinfectants and Antiseptics (SUMMARY)

  • Alcohols (50%-70%)
  • Aldehydes (in solution)
  • Halogens
  • Heavy Metals
  • Detergents
  • Phenolics
  • Gases

Applications and Precautions

A
  • Skin antiseptics
  • Disinfectants; kill endospores; toxic to humans
  • (Skin disinfectants) Used to disinfect drinking water; surface disinfectants
  • Eye drop (1% solution) Disinfectant; toxic at high concentrations
  • Skin antiseptics; disinfectants
  • Disinfectants at high concentrations; used in soaps at low concentration
  • Sterilization of heat-sensitive objects

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