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Eq ACVS Phase 1 > Ch.9 Instrument Preparation, Antisepsis and Disinfection > Flashcards

Ch.9 Instrument Preparation, Antisepsis and Disinfection Flashcards

1
Q

How long does Staphylococci live on scrubs - 60% cotton 40% polyester blend

A

1- 19 days

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2
Q

How long can Stephylococci and enterococci live on pure polyester

A

> 90 days

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3
Q

How should surgical clothing be washed to remove significant quantities of microorganisms according to the US Centres for Disease Control

A

160F/70C
50-150 ppm chlorine bleach

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4
Q

How should surgical clothing be washed to remove significant quantities of microorganisms according to the European Norm BS EN

A

80C for at least 10mins
or
60C for 60 mins - without reuse of the rinsing water

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5
Q

What does sterilisation refer to

A

Complete destruction
or elimination of
vegetative bacteria,
bacterial spores,
viruses and fungi
by physical or chemical methods.

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6
Q

Disinfection refers to

A

Many or all microorganisms are eliminated except bacterial spores

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7
Q

Disinfectants

A

Applied to inanimate objects
May be toxic to living tissue

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8
Q

The efficacy of disinfection and sterilisation is influenced by

A
  1. Organic/inorganic load present
  2. Instrument type
  3. Level of contamination
  4. Presence of biofilm
  5. Material of the object
  6. Concentration and exposure time of the chemical
  7. Temp & pH of the disinfection process
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9
Q

Critical items - definition, cleaning process, example

A

Definition: Penetrate the soft tissues, enters or contacts the bloodstream/sterile tissue.

Process: Clean, Disinfect, Sterilize

Example: All surgical instruments

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10
Q

SemiCritical items - definition, cleaning process, example

A

Definition: Contact mucous membranes or non intact skin, does not enter bloodstream/sterile tissue.

Process: Clean, High level Disinfect

Example: Endotracheal tubes, endoscopes

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11
Q

NonCritical items - definition, cleaning process, example

A

Definition:Contact skin but not mucous membranes

Process: Clean, Disinfect

Example: Stethoscope

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12
Q

Final processing of instruments should be performed within what time frame

A

6 hours

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13
Q

How does increasing water hardness affect cleaning of instruments

A

Reduces the effectiveness of blood removal in cold water prewashes

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14
Q

What is an acceptable alternative to manual cleaning

A

Prerinsing in an enzymatic cleaner

Some only req 2-10mins contact time
mjority need 30-45 at room temp

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15
Q

Advantages of Hydrox

A

Combines cleaning with microbial killing

This protects health care workers from infectious risks and reduces bioburden on instruments

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16
Q

Ideal pH of detergent solution

A

Neutral

Best material compatibility
Good soil removal

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17
Q

What should instruments be rinsed with after cleaning

A

Deionised water

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18
Q

Which has been shown to be more effective, automated cleaners or manually cleaning

A

Automated

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19
Q

How do ultrasonic cleaners work

A

High frequency vibratory waves which clean through cavitation and implosion
Waves of acoustic energy are propagated in aquous solution.
Disrupts air pockets ensuring thorough wetting

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20
Q

What must be done with the instrumenst following ultrasonic cleaning

A

Rinsed with demineralized water

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21
Q

Why is rinsing of instruments after cleaning essential

A

Cleaning fluid could result in endotoxin contamination of surgical instruments which may cause severe inflammatory rxns in tissues

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22
Q

Does ultrasonic cleaning provide any antimicrobial activity

A

No but it can act synergistically to increase bactericidal efficacy of a disinfectant

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23
Q

How do automated washer disinfectors disinfect instruments

A

Heat disinfection

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24
Q

Automated washer disinfector run through

A
  1. Cold rinse
  2. Main clean - product neutralization - 55C
  3. Rinse
  4. Disinfect - 90-93C for 5 mins
  5. Dry cycle

For a machine connected to tapwater with a hardness of 25 and incoming temp of 15c the cycle would take 54mins

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25
Q

What is an Ao value

A

Time equivalent
Number of seconds temp has reached **80c **or more

Measure of expended energy
temp/time

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26
Q

Disinfection over what Ao value is deemed highly secure

A

> 5000Ao

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27
Q

Ao value of the automated washer disinfectors

A

5985

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28
Q

Ao value of household diswashers

A

285

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29
Q

Least effective wrapping materials

A

Cotton and linen
<30days

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30
Q

Cautions when using packaging that contains cellulose

A

Not compatible for hydrogen peroxide gas plasma steriliation

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31
Q

Aluminium containers allow safe storage time of how long

A

Up to 1 year

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32
Q

How long should instruments rest before packaging and at what temp and humidity

A

Room temp 20-23c
30-60% humidity
2 hours min

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33
Q

Storage time, open shelf and closed cabinet
Single-wrapped muslim (2 layers)

A

Open shelf - 2 days
Closed cabinet - 7 days

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34
Q

Storage time, open shelf and closed cabinet
Double-wrapped muslim (2 layers each)

A

3 weeks - open shelf
7 weeks - closed cabinet

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35
Q

Storage time, open shelf and closed cabinet
Single-wrapped crepe paper

A

3 weeks - open
8 weeks - closed

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36
Q

Storage time, open shelf and closed cabinet
heat sealed paper and transparent plastic

A

At least 1 year - open/closed

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37
Q

What tests can be used to detect residual contamination of processed instruments

A

ATP bioluminescence

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38
Q

Why are biological indicators superior to chemical indicators

A

Measure the effective microbial killng power of the sterilization process

The spores used are more resistent and greater in numbers than are commonly found on surgical instruments

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39
Q

What does SAL describe

A

The probability of an item being non sterile afer it was exposed to the sterilization process

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40
Q

SAL of medical devices

A

10 to the minus 6
1/1,000,000

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41
Q

Difference between how dry heat and moist heat kill

A

Dry - oxidation and dehydration

Moist - Irreversible denaturation of enzymes and critical proteins

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42
Q

Typical sterilization cycle

A

Exposure time - 20mins at 121c for a SAL of 1 in 10,000

For each additional 2 mins at 121c SAL decreases by a factor of 10

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43
Q

Estimated bioburden on surgical instruments

A

1000

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44
Q

How do most autoclaves work

A

Gravity displacement
steam pressure drives air downward

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45
Q

Drying time in autoclave

A

15 - 30 mins

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46
Q

What is flash sterilization

A

Item is placed in an open tray
Rapid penetration of steam
eg 3 mins at 132c in prevacuum autoclave

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47
Q

Flash sterilization is contraindicated in what instruments

A

Implants

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48
Q

Highest tolerated leak rate of steam sterilizer

A

1mmHg/min

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49
Q

Test to prove air removal and steam penetration within dense packaging are complete

A

Bowie-Dick

50
Q

Temp, pressure, time for sterilization of glass, porcelain, metal or porous items using steam

A

Steam heat: 121-124c
200kPa-2.0 atm
20 mins
SAL 10,000

134-138c
300kPa-3atm
5 mins

51
Q

Temp, pressure, time for sterilization of glass, porcelain, metal or porous items using dry heat

A

160c
180mins

170c
80mins

180c
30mins

52
Q

Temp, pressure, time for sterilization of wrapped instruments and textiles items using steam

A

121c
200kPa 2.0atm
30 mins

132c
200kPa 2atm
25 mins
SAL 1,000,000

53
Q

Draw backs of using LTS - Low Temp Sterilization

A

Inneffective against proteins and salt residues

Once lumen drops below 3mm - decresed efficacy

54
Q

How does ethylene oxide work

A

Alkylating agent
innactivates DNA and RNA
effective against vegetative bacteria, fungi, viruses, spores

Highly flammable - usually mixed with Freon or CO2 to reduce flammability

55
Q

EtO (ethylene oxide) sterilization process

A
  1. Pre conditioning & humidification
  2. Gas introduction
  3. Exposure
  4. Evacuation
  5. Air washes

2.5 hours

56
Q

What can reduce effectiveness of EtO below lethal point

A

Water/condensation

57
Q

What is better at sterilizing vetwrap, steam or EtO

A

EtO

58
Q

How long should an implant ve aerated post EtO prior to use

A

2 weeks

59
Q

For how long should instruments be allowed to aerate at room temp following EtO

A

7 days

to avoid tissue toxicity

60
Q

Mechanical aeration of EtO in gas sterilizers

A

8-12 hours at 50 - 60c

61
Q

Advantages of hydrogen peroxide gas plasma

A

Short instrument turnaround time 50-75mins
No health hazards
Low temp <50c
Safe for heat and moisture sensitive instruments

62
Q

How does hydrogen peroxide gas plasam sterilization work

A

Aqueous solution of hydrogen peroxide injected into the chamber
Converted to gas plasma by radio waves
Create an electrical field
Vapor converted to free radicals
Collide with and inactivate microorganisms

63
Q

Instruments not suitable for gas sterilization with Hydrogen Peroxide

A

Flexible endoscopes
Items derived from plant fibers; linens, gauze, cast padding, tongue depressors

64
Q

Effective liquid sterilization system for heat sensitive, complex design flexible endoscopes

A

Steris System 1E
Table top
25mins

65
Q

Steris System 1E Liquid sterilization process

A

Water is filtered,
UV sterilized and
Mixed with Steris S40 concentrate - mix of 40% acetic acid, 35% peracetic acid, 6.5% hydrogen peroxide

Solution is circulated in chamber of machine
Pumped through endoscope chanels

66
Q

What is high level disinfection

A

Chemical exposure times insufficient to achieve sterilization
but
sufficient to inactivate all microorgs except spores

FDA definition: Sterilant used for a contact time that obtains a 6-log10 kill of a Microbacterium

67
Q

Trade name, action, effect, disadvantages of Isopropyl alcohol

A

Trade: Propanol

Action: Protein dentaturation

Effect: Bactericidal, effective against vegetative bacteria only

Disadvantages: Poor against spore, fungi, viruses, cytotoxic in tissue

68
Q

Trade name, action, effect, disadvantages of Propan-2-ol, Propan-1-ol

A

Trade: Sterillium

Action: Protein dentaturation

Effect: Bactericidal, fungicidal, effective against many important viruses,

Disadvantages: Cytotoxic in tissue

69
Q

Trade name, action, effect, disadvantages of Ethanol 96% and Biphenyl-2-ol

A

Trade: Desderman pure

Action: Protein dentaturation

Effect: Bactericidal MRSA, fungicidal, effective against many important viruses,

Disadvantages: Cytotoxic in tissue

70
Q

Trade name, action, effect, disadvantages of glutaraldehyde

A

Trade: Cidex, Omnicide, Abocide

Action: Protein & nucleic acid dentaturation

Effect: Bactericidal, fungicidal, viricidal

Disadvantages: Long 10 hour exposure time for sporocidal effect, limited shelf life once activated, Cytotoxic in tissue

71
Q

Trade name, action, effect, disadvantages of Chlohexadine

A

Trade: Nolvasan

Action: Cell membrane disruption and cellular protein precipitation

Effect: Bactericidal, fungicidal, variable viricidal

Disadvantages: Not sporicidal

72
Q

Trade name, action, effect, disadvantages of Povidone-iodine

A

Trade: Betadine

Action: Metabolic interference

Effect: Bactericidal, fungicidal, viricidal

Disadvantages: Poorly sporicidal, some inactivation by organic debris

73
Q

Trade name, action, effect, disadvantages of 1.Octenidine and
2.Polyhexamethylene biguanide

A

Trade: 1.Octenisept
2.Lavasept

Action: Cell membrane disruption

Effect: Bactericidal, fungicidal

Disadvantages: Not sporicidal

74
Q

Glutaraldehyde GH is affective against

A

Broad spec antimicrobial - bacteria, fungi, viruses, mycobacteria

Low conc 0.1% - inhibits germination of spores
High conc 2% - sporicidal

Deactivates teteanus toxoid

75
Q

Mode of action of GH

A

Binds to outer layers of microorganisms
Alkylation of sulfhydryl RNA, DNA and protein synthesis

76
Q

GH is more active in alkaline or acidic solutions?

A

Alkaline
pH 7.5 - 8.5

but high pH shortens its shelf life

77
Q

When should GH soltion be considered unsafe

A

Test indicates dilution of 1-1.5% GH

78
Q

Disadvantages of GH

A

Can produce biofilm
Corrosive
Tissue toxicity

79
Q

How to dispose of GH

A

Neutralise with Sodium bisulfate first

80
Q

Cidex as a steriliant - time and temp

A

25c
10hours

81
Q

Cidex as a high level disinfectant

A

25c
45mins

82
Q

Cidex as an intermediate level disinfectant

A

20-25c
10min

83
Q

OPA - how long to destroy all common bacteria

A

5 mins europe
10 mins canada,australia
12 mins usa

at 20c

84
Q

Advantages of OPA

A

No noxious gas,
no activation req
compatible with all materials
does not coag blood or fix tissues to instruments
stable at pH 3-9

85
Q

Disadvantages of OPA

A

Decreaed suscpetibility to P. aeruginosa

Irritant to resp tract/eyes

Stains inc skin

Anaphylactic rxns

86
Q

Succindialdehyde is recommended for

A

Flexible endoscopes, us probes

87
Q

Liquid formalin contains what % formaldehyde

A

37%

88
Q

What does formaldehyde kill and how

A

Bacteriacidal
Tuberculocidal
Fungicidal
Virucidal
Sporicidal

Alkylates amino and sulfhydryl groups of proteins and ring nitrogen atoms of purine bases

89
Q

Formaldehyde-alcohol vs formaldehyde

A

Formaldehyde-alcohol - steriliant

Formaldehyde - high level disinfectant

90
Q

Mode of action of peractetic acid PAA

A

Oxidizing agent
Denature protein
Disrupt cell wall
Oxidate sulfhydryl and sulfur bonds

91
Q

PAA vs GH

A

PAA- Cidex 0.35% Steris 0.20%

PAA similiar to better biocidal efficacy
Contact time 10-15 mins
Conc 0.09%

Inativte G+, G- bact, fungi, yeasts in <5mins at <100ppm
Effective against mycobacteria 20-30mins at 0.26% even with organic load

Less health risk
Does not create biofilm

Less stable than GH
Corrosive
Carcinogen
Dull aluminium

92
Q

Action of Hydrogen peroxide

A

Hydroxyl radicals - attack membrane lipids, dna, cellular components

93
Q

Hydrogen peroxide is better against G+ or G-

A

G+

94
Q

% of H202 required for sterility

A

6-25%

95
Q

% H202 for cleaning medical devices

A

0.5%

96
Q

Conc of household bleach

A

5-6%

97
Q

Cidex OPA - Peracectic acid - activity

A

All microorgs minus spores in 20 mins

98
Q

Virkon - Peroxygenic Acid

A

Foot baths/mats
Cant destroy endospores and molds in practical timeframe

99
Q

What are the most potent antiseptics

A

alcohols

100
Q

Alcohols bacteriocidal or static

A

cidal

101
Q

optimum conc of alcohol

A

60-90%
if 100% less bactericidal - needs water to denature proteins

102
Q

The antimicrobial activity of alcohol is influenced by what

A

Length of its carbon chain and branching

103
Q

Rank the bactericidal efficay of alcohols

A

n-propanol>isopropanol>ethanol

104
Q

which alcohol is strongest against viruses

A

ethanol

105
Q

Alcohol in combination with povidone iodine

A

Potentiates the antimicrobial effect by increasing release of free iodine

106
Q

Mode of action of chlorhexidine

A

TARGETS CYTOPLASMIC MEMBRANE
causing precipitation or coagulation of protein and nucleic acid

Injures the outer membrane in G- and cell wall in G+

Is not sporicidal but prevents development by inhibiting outgrowth but not germination

107
Q

Efficacy of chlorhexidine against viruses

A

Effective against enveloped but not against naked viruses ie rota, aden, entero

108
Q

At 1-2.5ug/ml chlorhexidine acts as bacteriststic or cidal?

A

Bacteriostatic

20ug/ml req for bacteriocidal

109
Q

Chlorhex lacks activity against what bacteria

A

Some G-
Pseudomonas
Providentia

(unless combined with edta)

at 4% lacks activity against Enterococcus

110
Q

Toxic effects of Chx gluconate

A

Highly ototoxic
High damaging to cornea
Anaphylactic shock

111
Q

Advantages of Iodine

A

Most effective agent against MRSA
Fast acting at low conc so little resistance

112
Q

Mechanism of action of Iodine

A

Penetrates cell wall causing disruption of protein and nucleic acid structures

113
Q

Betadine composition

A

10% sol with 1% iodine

Iodine in sol with polyvinylpyrrolidone
(PVP-I2)

only 0.8ppm free iodine as binds to PVP so may not be sufficient

DILUTE WITH H20 TO FREE IODINE

114
Q

Surface contact time to release free iodine from PVP-I2

A

At least 2 mins

115
Q

Which are more effective against spores, water mixtures or alcohol mixtures of iodine

A

water mixtures

116
Q

Up to what % PVP-I2 can be used on the cornea

A

10%

available as a 5% opthalmic sol

117
Q

Use of pvp-i2 in eyes as tx

A

irrigation of conjunctival sac with a 5% sol of comparable efficacy as a 3 day course of topical abx

118
Q

Mode of action of Octenidine

A

Interacts with polysaccharides in cell wall and cytoplasm of microorganisms - leakage of cytoplasmic membrane and cell death

119
Q

Benefits/Risks of pHisoHex

A

Prolonged residual activity
Not adversely affected by organic material

Neurotoxic from dermal exposure

120
Q

Polyhexamethyene Biguanide PHMB is widely used in what

A

wound dressings as low cytotoxicity against keratocytes and fibroblasts

121
Q

repeat exposure of p. aeruginosa to 5mg/L chx resulted in what

A

Increase MIC fromn 10-70mg/l within 6 days

Eq ACVS Phase 1 (72 decks)

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