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Disinfection Flashcards

0
Q

UV light for decontaminating. What wavelength?

A

254 nm

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1
Q

Abbreviation SAL regarding disinfection

A

Sterility Assurance Level

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2
Q

Decontamination is defined by CDC as:

A

Reduces the level of microbial contamination so that infection transmission is eliminated.

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3
Q

The amount of paraformaldehyde flakes that is typically used to generate the required amount of formaldehyde gas for area or BSC decontamination is:

A

0.3 g/cu. ft.

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4
Q

The microorganism that is considered least resistant to inactivation by chemical or physical means would be:

A

Lipid or medium sized viruses

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5
Q

According to Spaulding’s classification of device surfaces, semi-critical medical devices come into contact with mucous membranes and require what level of disinfection prior to reuse?

A

High

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6
Q

The generally accepted level for an SAL is:

A

1: 1,000,000

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7
Q

An Fo is the equivalent exposure time at what temperature?

A

121 degrees C

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8
Q

Which level of chlorine is considered appropriate by CDC and WHO for most intermediate level disinfection?

A

500-1000 ppm

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9
Q

When choosing a uv meter for measuring uv light used for disinfection, it is most important that:

a. It is battery operated
b. Gives readings in microwatts/cm2 with peak response at 254 nm
c. Deducts background radiation level
d. Is hand held
e. Gives readings in microwatts/cm2 with peak response at 298 nm

A

b. Gives readings in microwatts/cm2 with peak response at 254 nm

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10
Q

Which organism is used as a biological indicator to test gamma radiation sterilization processes?

a. Geobacillus stearothermophilus
b. Bacillus megaterium
c. Bacillus pumulis
d. Bacillus radiothermans
e. Bacillus atrophaeus

A

c. Bacillus pumulis

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11
Q

Sterilization is described as the elimination of all viable microorganism; disinfection generally refers to:

a. The elimination of all pathogens
b. The elimination of bacteria and Mycobacterium tuberculosis
c. The reduction of organisms to an acceptable level
d. The elimination of vegetative bacteria and viruses

A

c. The reduction of organisms to an acceptable level

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12
Q

The term “D-value” used in reference to sterilization refers to:

a. The time needed to reduce the concentration of a given organism by 90%
b. The number of degrees above 121o C that is required to kill off 106 organisms
c. The number of degrees above 100 o C that is required to kill off 106 organisms
d. The time needed to reduce the concentration of a given organism by 50%
e. The level of destructiveness of an autoclave cycle as measured by thermocouples

A

a. The time needed to reduce the concentration of a given organism by 90%

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13
Q

Which of the following sterilization methods would not be effective for equipment or materials that are placed inside of a paper wrap?

a. EtO
b. Vaporized H2O2
c. Gamma sterilization
d. UV light
e. Steam autoclave

A

d. UV light

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14
Q

Which of the following disinfectants is not considered toxic?

a. Isopropyl alcohol
b. Quaternary ammonium compounds
c. Chlorine compounds
d. Hydrogen peroxide
e. Depending on the level, all of the above could be considered toxic.

A

e. Depending on the level, all of the above could be considered toxic.

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15
Q

The sterilization method of choice for a reusable piece of equipment that is basically polyethylene with pvc tubing, natural rubber gaskets, and nylon tabs, would be:

a. Steam at 121oC
b. Vaporized H2O2
c. Ethylene Oxide
d. Dry heat

A

c. Ethylene Oxide

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16
Q 
Rank the following in order of their resistance to physical and chemical treatments, with 1 meaning most resistant and 7 meaning least resistant:
\_\_ fungi
\_\_ vegetative bacteria
\_\_ lipid viruses
\_\_ non-lipid viruses
\_\_ bacterial spores
\_\_ prions
\_\_ mycobacteria
A

(5,6,7,4,2,1,3)

__ prions
__ bacterial spores (anthrax, clostridium)
__ mycobacteria (TB)
__ non-lipid or small viruses (polio virus, coxsackievirus, rhinovirus, HAV)
__ fungi
__ vegetative bacteria
__ lipid viruses (Herpes simplex, CMV, RSV, HBV, HCV, HIV, hantavirus, ebola virus)

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17
Q

Higher concentrations of an active ingredient in a disinfectant may not always relate to a higher microbicidal activity. That is known to be true about the following material:

a. chlorine bleach solution
b. ethanol
c. glutaraldehyde
d. phenol

A

b. ethanol

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18
Q

A disinfectant classified as a “hospital disinfectant” by the EPA generally falls into the following ranking system that is commonly used by CDC:

a. High level disinfectant
b. Moderate level disinfectant
c. Low level disinfectant
d. Low or moderate level disinfectant, depending on formulation
e. Moderate or high level disinfectant, depending on formulation

A

d. Low or moderate level disinfectant, depending on formulation

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19
Q

Sterilization

A

destroys all microbial life, including high numbers of bacterial spores

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20
Q

Disinfection

A

eliminates nearly all recognized pathogens, disease causing organisms, but generally not spores, on inanimate surfaces

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21
Q

Antisepsis

A

reduction of organisms on living

tissues

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22
Q

Biocide

A

kills type of organism or
group, e.g., tuberculocide, virucide,
sporocide, etc.

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23
Q

Biostat .

A

prevents organisms or group
from growing, e.g., bacteriostat,
fungistat, etc

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24
Q

Sanitizer

A

Reduces level of organisms

to a safe level, i.e., cleaning objects

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25
Q

HPV Safety issues

A

• Toxic but not mutagenic or
carcinogenic
• 35% liquid - skin and eye irritant
• Monitor vapor leakage with detector (e.g., Drager) tube

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26
Q

iodophors

A
  • Can be aqueous, tincture (in alcohol) or iodophor (complexed with surfactant)
  • Usually intermediate level disinfectant
  • Can cause staining and corrosion
  • Easily neutralized by organics.
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27
Q

Hand Sanitizers alcohol percentage

A

They should contain no less than 60% alcohol

in order to effective.

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28
Q

benzalkonium chloride sanitizers

A

Some benzalkonium chloride sanitizers have
been shown effective against MRSA and flu

quaternary ammonium compound

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29
Q

Hand sanitizer limited efficacy against:

A

Limited efficacy against Norwalk virus; NOT

effective against Cl. difficile

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30
Q

ETO Validation parameters

A 
• Critical parameters measured:
– temperature
– pressure/vacuum
– gas concentration
– humidity
– time
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31
Q

Gamma radiation average dose

A

2.5 Mrad

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32
Q

ETO Validation biological indicator

A

• Biological indicator used is Bacillus atrophaeus (B. subtilis var. niger)

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33
Q

Gamma radiation biological indicator

A

Bacillus pumilus

34
Q

Gamma radiation General

A
  • Most common for food and devices
  • Good penetration
  • Dosimeters used to quantify dose
35
Q

Ultrasound general

A

– Used on a suspension of liquids
– Combined with chemicals /detergents can be used to
inactivate microorganisms, e.g.,detergent and sonication will inactivate retroviruses

36
Q

Chlorine Dioxide Gas condition of use

A
  • Concentration of 10 mg/L
  • Contact time of 1-2 hours
  • High humidity optimal
37
Q

Chlorine Dioxide biological indicator

A

Bacillus atrophaeus

38
Q

Chlorine Dioxide • Advantages

A

– No harmful emissions (gas neutralized by sodium bisulfite)
– No residues
-broken down by light
-doesn’t form byproducts like bleach

39
Q

Chlorine Dioxide Disadvantages

A

– Incompatible with uncoated
ferrous metals and latex rubbers
– Toxic – PEL of 0.1 ppm (0.3 mg/M3), STEL of 0.3 ppm
– Compatibility issues with electronics? (USEPA, Porton
Down studies)

40
Q

CDC Classification of Disinfectants

• High –

A

can kill spores with long contact time.
Used for critical and semi-critical medical
devices.

Aka “sporocide/sterilant”

41
Q

CDC Classification of Disinfectants

• Intermediate –

A

kills all bacteria (including
mycobacteria) except spores, fungi and
inactivates most viruses. Used for noncritical/
environmental surfaces (OK for BBP).

Aka “tuberculocidal hospital disinfectant”

42
Q

CDC Classification of Disinfectants

• Low –

A

kills vegetative bacteria, some viruses and
fungi. Used for non-critical devices/ surfaces.

Aka “hospital disinfectant/sanitizer”

43
Q

Dry Heat Sterilizers

• Cycle parameters:

A

– 170 C - 1 hour
– 160 C- 2 hours
– 140 C - 3 hours
– 121 C - overnight

44
Q

Dry Heat Sterilizers

When are they used

A

• Used for materials that are damaged by
steam, cannot be penetrated by steam or
gases, or must be endotoxin free

45
Q

Dry Heat Sterilizers indicator organism

A

• Bacillus atrophaeus is indicator organism

46
Q

Ethylene Oxide Sterilizers

Primary use

A

for heat / radiation sensitive dry medical supplies

47
Q

Ethylene Oxide Sterilizers

hazards

A

• Carcinogenic and an eye irritant
• Mixtures with freon and CO2 are not
explosive; pure ethylene oxide is!

48
Q

Ethylene Oxide Sterilizers

conditions of use

A 
• Absorbs to materials and must be
degassed after exposure
• Generally use 500-1000 mg/liter at
49-50 C with a pre-humidification
cycle
49
Q

Peracetic Acid

concentration for use

A

– Sporocidal – at levels down to 100 ppm

2500 ppm kills B.anthracis in 30 mins

50
Q

Peracetic Acid

what used on and when?

A

– Used for food processing equipment
and some medical devices b/c non toxic residuals
– Effective at low temperature and in presence of organics

51
Q

Viral Resistance
– Sensitivity based on lipoprotein coat (Klein-Deforest
scheme)

• Low - Lipid viruses

List examples

A

HIV, HBV, RSV, Herpes

52
Q

Viral Resistance
– Sensitivity based on lipoprotein coat (Klein-Deforest
scheme)

• Moderate- Non-lipid, hydrophilic

List examples

A

Polio, rhino,

coxsackie, HAV

53
Q

Viral Resistance
– Sensitivity based on lipoprotein coat (Klein-Deforest
scheme)

• High - Non-lipid, small

List examples

A

Adenovirus, rota, parvo

54
Q

Viruses with high protein (serum or mucin) load and disinfection

A

Can make certain lipophilic viruses, e.g., influenza, as difficult to kill as nonenveloped viruses!

55
Q

D-Value – Decimal Reduction Time

A 
Time required to
kill 90% of
organisms or
achieve 1 log10
reduction under
set conditions
56
Q

Formaldehyde BI

A

Bacillus atrophaeus is the BI

57
Q

paraformaldehyde flakes for decon

Concentration in PPM by volume and % concentration by weight

A

10,000 ppm by volume and about 0.8%

concentration by weight

58
Q

Formaldehyde gas decon temp and RH conditions

A

• Temperature of at least 70oF or 20oC

• Relative humidity of >70% - efficacy depends
on RH

Can polymerize in the presence of moisture

59
Q

How neutralize formaldehyde decon?

A

• Neutralized with 110-120% of ammonium

carbonate

60
Q

Hydrogen Peroxide Vapor

indicator

A

G. stearothermophilus

61
Q

Dry Fogs

chemicals used

A

• Using peracetic acid (peroxyacetic
acid) or similar compounds
• Generate ultra fine atomization of
droplets less that 10 u

62
Q

Dry Fogs

Biological indicators

A

Bacillus stearothermophilus spores

63
Q

Dry fogs

Advantages

A
  • Starting material is less hazardous and by products are acetic acid and water
  • Does not seem to adversely effect electronics
  • Relatively tolerant of high soil loads
  • Fairly quick and cost effective
64
Q

Uses for Dry Fog

A
  • To control mold contamination in sick buildings
  • Surface decontamination in pharmaceutical/ medical device cleanrooms, hospital areas, containment labs, etc.
  • Odor reduction in animal facilities, locker rooms, etc.
65
Q

Incinerator dual chamber paramaters

A

• Dual Chamber Operation parameters:
– Primary chamber: 1400F-1800F (760C-982C)
– Secondary chamber: >2000F (1093C)

66
Q

Incinerator percentage volume of waste reduction

A

85-95%

67
Q

Formaldehyde safety issues

A
  • Toxic substance and carcinogen: eye irritant.
  • Reactive with HCl / chlorine compounds
  • Employee exposure limits are low
68
Q

Formaldehyde safety issues

OSHA 15 minutes STEL

A

2 ppm

69
Q

Formaldehyde safety issues

8 hour TWA

A

0.75 ppm

70
Q

Formaldehyde safety issues

NIOSH IDLH

A

20 ppm

71
Q

Peroxygens

A

hydrogen peroxide/peracetic

acid

72
Q

NaOH concentration effective against viruses

A

1-2%

73
Q

NaOH concentration effective against prions

A

1-2 N for 1 hour

74
Q

Which is the preferred method for treatment of animal

bedding? What else is that best for?

A

Incineration
Also good for carcasses and pathological waste
not good for plastics

75
Q

• Why is alcohol not generally acceptable for use for

bloodborne pathogen contamination?

A

low level and no residual

76
Q

• Which chemicals are used to decontaminate prion

contaminated surfaces?

A

– 2 % sodium hypochlorite for 1 hour
– 2 N NaOH for 1 hour
– Environ LpH

77
Q

• Chlorine bleach solutions degrade quickly because
of tap water impurities and should be prepared daily.
True or False?

A

True

78
Q

• How many ppms of chlorine should be used for

routine lab disinfection?

A

• 500-1,000 ppm are appropriate for most
intermediate level disinfection
• 5,000 ppm is used for spill clean-up,
heavily soiled areas, liquid wastes

79
Q

• Peracetic acid is sporocidal. What are some of it’s

benefits over other disinfectants.

A 
• Starting material is less hazardous
and by products are acetic acid and
water
• Doe not seem to adversely effect
electronics
• Relatively tolerant of high soil loads
80
Q

• How many ppms of chlorine should be used for
prion
decontamination?

A

• 20,000 ppm is recommended for prion

decontamination

81
Q

• How many ppms of chlorine should be used for spill clean-up,
heavily soiled areas, liquid wastes

A

• 5,000 ppm is used for spill clean-up,

heavily soiled areas, liquid wastes

82
Q

• How many ppms of chlorine should be used to remove bacterial
films

A

• 50,000 ppm is used to remove bacterial

films

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