Sterilization And Disinfection Flashcards

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1
Q

Sterilization definition

A

Removal of pathogens including spores

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2
Q

Disinfection definiton

A

Removal of Pathogens but not spores

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3
Q

Asepsis definition

A

To make body surface/skin/wound free of mirco-organisms

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4
Q

Sterilization methods are divided into

A

Physical
Chemical

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5
Q

Physical Sterilization methods includes

A

Heat
Filtration
Radiation

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6
Q

Chemical sterilization methods includes

A

Alcohol
Aldehydes
Phenols
Halogens
Oxidizing agents
Plasma sterilization
Gas sterilization
Heavy metal salts
Surface acting agents
Dyes

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7
Q

Heat method of Sterilization is divided into

A

Dry heat
Moist heat

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8
Q

Examples of Dry heat methods

A

Candle
Flame burners
Sunlight
Hot air oven
Incinerator

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9
Q

Mechanism of Dry heat Sterilization methods

A

CODE
Charring
Oxidative damage
Denaturation of proteins
Elevation of electrolytes

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10
Q

Hot air oven temperature and duration

A

160°C for 2 hr
For every 10° increase in temperature - time should be decreased by half
For Ex. 170°C × 1hr, 180°C x 30 min

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11
Q

Hot air oven is used to sterilize

A

Glasswares
Cotton swabs
Wax, oils, powder gels
Dusting powder
Greasy paraffin wax
Metallic (sharp and non sharps)

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12
Q

Physical control of Hot air oven

A

Temperature monitoring by thermocouples

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13
Q

Chemical control of Hot air oven

A

Brownies tube (green spot)

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14
Q

Biological control of Hot air oven is done by

A

C. Tetani or Bacillis subtilis/atropheus

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15
Q

Incinerator is used for sterilization of

A

Hospital waste
Human anatomical waste
Animal carcasses
Expired Cytotoxic drugs

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16
Q

Temperature maintained in Incinerator

A

2 chambers - 700-800°C and 1000-1100°C

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17
Q

Mechanism of Moist heat Sterilization

A

Coagulation and denaturation ot proteins

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18
Q

Which Heating sterilization method is considered better - Dry or Moist heat

A

Moist heat

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19
Q

Moist heat Sterilization methods classification on basis of temperature

A

1) Below 100°C - IPL100 - Inspissation, Pasteurisation, Vaccine water bath
2) At 100°C - BAT - Boiling and Tyndalisation
3) Above 100°C - Autoclave

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20
Q

Methods or Milk Pasteurisation

A

Holder method
Flash method
Ultra high temperature method

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21
Q

Holder method of milk Pasteurisation temperature and duration

A

63°C for 30 minutes

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22
Q

Temperature and duration of Flash method of Milk Pasteurisation

A

72°C for 20 seconds - Rapidly cool it to <13°C

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23
Q

Ultra high temperature method of Milk Pasteurisation

A

149°C for 1-2 sec

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24
Q

Which method of Milk Pasteurisation is better

A

Flash method as it kills Coxiella brunetti

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25
Q

Tests for efficacy of Pasteurisation

A

1) Phosphatase test - On adding substrate - no color change (enzymes denatured)
2) Coliform test - No growth on MacConkey agar

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26
Q

Temperature and duration for Inspissation method

A

80°C for 20-30 min for 3 consecutive days
80-80-80

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27
Q

Inspissation method is used for sterilization of

A

Lowenstein Jensen media
Loeffler’s serum slope

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28
Q

Temperature and duration of Vaccine water bath method and uses

A

60°C for 1 hour
Bacterial vaccines are heat inactivated

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29
Q

Temperature and duration for Boiling method

A

At 100°C for 15 min
Doesn’t kill spores

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30
Q

Temperature and duration for Tyndalisation method of Sterilization

A

At 100°C for 20 min for 3 consecutive days
Kill spores

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31
Q

Tyndalisation Method is used for sterilization of

A

Used for media with gelatin/sugar
TCBS
XLD
DCA
Selenite F broth

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32
Q

Temperature and duration of Autoclave method

A

121°C for 15 min for 15psi
To kill Prions - 134°C × 1.5 hrs

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33
Q

Control used for Autoclave

A

Bacillus Stearothermophilus

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34
Q

Uses of Autoclave method

A

Instruments (non sharps)
Aprons
Sutures except catgut sutures
Media except LJ and LSS
Sputum (prior to descending)

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35
Q

Average Pore size in Filtration method

A

0.22 micron

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36
Q

Types of Filtration methods

A

Depth filters
Membrane filters

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37
Q

Depth filters include

A

Candle filters
Seitz filters - not used
Glass filters

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38
Q

Membrane filters includes

A

Cellulose acetate
Cellulose nitrate

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39
Q

Uses of Filtration method of Sterilization

A

For heat sensitive substances
Vaccine
Antibiotics
Serum
Toxins
Sugar solutions

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40
Q

Control of Filtration method is done by

A

Brevendimonas diminuta (chota chota)
Serratia

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41
Q

HEPA full form and its efficacy

A

High efficacy particulate air filter
99.97% efficacy

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42
Q

ULPA full form and it’s efficacy

A

Ultra low particulate air filter
99.999% efficacy

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43
Q

Types of Radiation methods of Sterilization

A

Ionizing (Cold radiation)
Non ionising (Hot radiation)

44
Q

Penetrating power of Ionising and Non ionizing radiation methods

A

Ionizing - High penetrating power
Non ionizing - low penetrating power

45
Q

Which radiation method is Sporicidal

A

Ionising - Sporicidal
Non ionising - Bactericidal only

46
Q

Ionising radiation includes which rays

A

X rays
Gamma rays
Cosmic rays

47
Q

Non ionizing radiation includes which rays

A

UV Rays
Infrared Rays

48
Q

Uses of Non ionising radiation method

A

OT Fumigation
Biosafety cabinet

49
Q

Types of Alcohol used for Sterilization

A

Ethyl alcohol (70%) - Spirit
Isopropyl alcohol (70-80%)

50
Q

Thermometer and Stethoscope are sterilized by

A

Isopropyl alcohol

51
Q

Aldehydes used for Sterilization

A

Formaldehyde
Formalin
Glutaraldehyde
Ortho-phthaldehyde (OPA-Cidex)

52
Q

Formaldehyde uses

A

Gas - OT Fumigation
10% NBF - For fixation of L/M

53
Q

Formalin uses

A

Preserve Specimens (human)
Duckering - killing bacillus anthracis spores from animal wool

54
Q

Glutaraldehyde uses

A

Also known as CIDEX
Used to sterilize Bronchoscope and Laryngoscope

55
Q

Glutaraldehyde/CIDEX is activated by

A

Alkalinization - active for 14 days

56
Q

Ortho-phthaldehyde (Opa-Cidex)

A

0.55% Solution
Cystoscopes etc
No activation needed and more stable
More Bactericidal activity

57
Q

Carbolic acid is first used by

A

Joseph Lister - Father of Antiseptic surgery

58
Q

Mechanism of Aldehydes

A

Cross Linking and alkylating the molecules

59
Q

Mechanism of Phenols for Sterilization

A

Protein precipitation and cell membrane damage

60
Q

Use of Phenol

A

For sterilization of Sharp instruments

61
Q

Types of Phenol

A

Phenol (5%)
Cresol (1-3%)
Lysol (2-5%)

62
Q

Savlon consists of

A

Chlorhexidine + Cetrimide

63
Q

Dettol consist of

A

Chloroxylenol

64
Q

Mechanism of action of Halogens

A

Oxidizing agents

65
Q

Iodine uses

A

Tincture iodine (2% iodine) - For skin Antiseptic
Providone iodine - Betadine (iodophore) - has residual action (better)

66
Q

Chlorine uses

A

1% sodium Hypochlorite - for blood spills
<10ml spill - 1:100
>10ml spill - 1:10

67
Q

Oxidizing agents includes

A

H2O2 - strong oxidizer, free radical injury
Paracetic acid - <1% is effective for spores

68
Q

Most effective concentration of H2O2 and concentration needed for spores

A

3-6% - most effective concentration
10% - needed for spores

69
Q

Meaning of Plasma in Plasma sterilization method or Sterrad

A

Plasma - gaseous state containing ions and electrons

70
Q

Process of Plasma sterilization or Sterrad

A

UV photons used
Vacuum
Low temperature
H202 chemical is present

71
Q

Advantages of Plasma sterilization method

A

No toxic residues
Short cycle time - 75 mins

72
Q

Uses of Plasma sterilization method

A

Surgical instruments eg - Arthroscope, Urethroscope etc

73
Q

Control of Plasma sterilization method

A

Bacillus Stearothermophilus

74
Q

Gas used for Gas Sterilization

A

Ethylene oxide

75
Q

Mechanism of action of Gas sterilization

A

Microbicidal
Sporicidal

76
Q

Side effects of Gas sterilization

A

Highly inflammable
Highly irritant
Highly explosive
Mix it will inert gases (3%)

77
Q

Factors affecting Ethylene oxide

A

Concentration
Humidity
Temperature
Entire cycle may take 18-24 hrs

78
Q

Uses of Gas sterilization

A

Pre packed syringes
Cardio pulmonary machines

79
Q

Control of Gas sterilization

A

Bacillus Globigi

80
Q

Heavy metal salts used for Sterilization

A

1% Silver nitrate - Opthalmia neonatarum
Silver sulphonamide creams - Burns
Mercury (Thiomersal) - antisera, vaccines

81
Q

Mechanism of action of Surface acting agents in Sterilization

A

Lowers the surface tension

82
Q

Anionic surface acting agents

A

Detergent like action
Weak antimicrobial activity
Ex. Soap

83
Q

Cationic surface acting agents

A

Quaternary ammonium compounds
More effective against Gram +ve than gram -ve bacteria
Ex - Cetrimide (Savlon)

84
Q

Amphoteric surface acting agents (TEGO Compounds)

A

Anionic + Cationic
Detergent + antimicrobial activity
Used as Antiseptic in dental procedures

85
Q

Dyes used for Sterilization

A

Aniline dye
Aeridine dye

86
Q

Aniline dyes

A

More active against gram +ve
Crystal violet
Gentian violet
Malachite green
Not active against Tb

87
Q

Aeridine dye

A

More active against Gram +ve
Can act in presence of organic waste
Aeriflavine
Proflavin

88
Q

Testing of disinfectant done by

A

Phenol coefficient test/Rideal walker test
Chick martin test/Modified Rideal walker test
Kelsey and Sykes test/Capacity test
Kelsey and Maurer test/Inuse test

89
Q

Phenol coefficient test/Rideal walker test

A

Highest dilution of disinfectant needed to kill S. Typhi broth divided by Highest dilution of phenol needed to kill S typhi broth more than 1

90
Q

Disadvantage of Phenol coefficient test/Rideal walker test

A

Don’t know efficacy with organic matter

91
Q

Chick Martin test/Modified Rideal walker test

A

Test disinfectant in presence of organic matter (yeast, Soil, feces)

92
Q

Kelsey and Sykes test/Capacity test

A

Capacity of disinfectant to be used in increasing microbiological load

93
Q

Kelsey and Maurer test/Inuse test

A

Done to test for contamination of disinfectant
Reality testing

94
Q

Organisms with decreasing order of Resistance

A

Physics chemistry bio mein gaye small Trophy nahi final large Prize won
Prions - most resistant
Cryptosporidium oocyst
Bacterial spores
Mycobacteria
Giardia cyst
Small non enveloped virus
Trophozoites
Gram -ve bacteria
Fungi
Large non enveloped viruses
Gram +ve bacteria
Enveloped virus - most susceptible

95
Q

Which organism is most resistant to Sterilization

A

Prions

96
Q

Which organisms are most susceptible to Sterilization

A

Enveloped virus

97
Q

Spaulding classification

A

Critical device
Semi critical device
Non critical device
Non critical surfaces/medical equipments

98
Q

Critical device examples and disinfection

A

Penetrate/Enter sterile devices
High level disinfectant/chemical sterilant

99
Q

Semi critical device and disinfection

A

Come in contact with mucus membrane
HLD

100
Q

Non critical devices and disinfection

A

Come in contact with skin
Intermediate/LLD

101
Q

Non critical surfaces/medical equipments and disinfection

A

Computer,desks,tables
LLD

102
Q

Intermediate level disinfectant includes

A

Isopropyl alcohol
Iodophore
Phenol

103
Q

Low level disinfectant includes

A

Chlorhexidine
Quaternary ammonium compounds

104
Q

Sporicidal agents

A

EFGHAPPPT
Ethylene oxide
Formaldehyde
Glutaraldehyde
H202, Hot air oven, 1% Hypochlorite
Autoclave
Per acetic acid
Plasma sterilization
O-pthalic acid
Tyndalisation

105
Q

Sterilization of Prions

A

Critical device - Treat it with 1N NaOh and 121°C for 30 min then routine Sterilization