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Medical Microbiology I > Sterilization, Disinfection, and Antisepsis > Flashcards

Sterilization, Disinfection, and Antisepsis Flashcards

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1
Q

Sterilization definition

A
  • Total destruction of all microbes including the more resilient forms such as bacterial spores, mycobacteria, non-enveloped viruses, and fungi
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2
Q

Disinfection definiton

A
  • Destruction of most organisms

- More resilient microbes can survive some disinfection procedures

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3
Q

Antisepsis definition

A
  • Use of agents on skin or other living tissue to inhibit or eliminate the number of microbes
  • No sporicidal action
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4
Q

Germicide definition

A
  • Chemical agent capable of killing microbes

- Spores may survive

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5
Q

Sterilization

A
  • Renders materials to be free of life forms

- Uses physical or chemical agents

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6
Q

Sterilization methodologies

A
  • Filtration
  • Dry heat
  • Moist head
  • Radiation (used when something cannot be heated)
  • Gas vapor sterilants
  • Chemical sterilants
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7
Q

Filtration (sterilization)

A
  • Removing bacteria and fungi from air with high efficiency particulate air (HEPA) filters
  • Unable to remove viruses and some small bacteria
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8
Q

Moist heat and dry heat (sterilization)

A
  • Autoclave
  • Most commonly used in hospitals
  • Indicated for most materials unless heat sensitive or toxic or volatile chemicals
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9
Q

Radiation (sterilization)

A
  • Ultraviolet or ionizing radiation
  • Microwave or gamma rays
  • Limitation of ultraviolet radiation is that direct exposure is required
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10
Q

Gas vapor sterilants (sterilization)

A
  • Ethylene oxide

- Formaldehyde gas

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11
Q

Ethylene oxide

A
  • Highly efficient

- Strict regulations limit its use because the gas is flammable, explosive, and carcinogenic

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12
Q

Formaldehyde gas

A
  • Limited because it is carcinogenic

- Use is restricted to sterilization of HEPA filters

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13
Q

Moist heat sterilization

A
  • Boiling water inefficient because maintaining a temperature greater than 100 degrees C difficult
  • Boiling vegetative organisms kills them, but spores remain viable
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14
Q

Autoclave

A
  • Device that creates steam under pressure for sterilization
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15
Q

Moist heat sterilization temperatures

A
  • Achieve higher temperature of 121 to 132 degrees C
  • Rate of killing is rapid
  • 15 to 30 minutes
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16
Q

Dry heat effectiveness of sterilization

A
  • Effective if applied at a high temperature for a long duration
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17
Q

Chemical sterilization effectiveness

A
  • Slow process

- Influenced by the concentration of the gas, relative humidity, exposure time, and temperature

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18
Q

Effectiveness of sterilization

A
  • Improves with a higher concentration, elevated temperatures, and a relative humidity of 30%
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19
Q

Ethylene oxide

A
  • Colorless gas, soluble in water and common organic solvents
  • Used to sterilize heat-sensitive items
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20
Q

Ethylene oxide sterilization process

A
  • Relatively slow

- 2 to 5 hrs

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21
Q

Doubling ethylene oxide concentration

A
  • Reduces exposure time by 50%
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22
Q

Ethylene oxide sterilization process is influenced by

A
  • Concentration of gas,
  • Relative humidity and moisture content of the item to be sterilized
  • Exposure time (2-5 hrs)
  • Temperature (29 to 65 degrees C)
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23
Q

Hydrogen peroxide (gas vapor sterilant)

A
  • Effective sterilants because of the oxidizing nature of the gas
  • Used for the sterilization of medical instruments
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24
Q

Plasma gas sterilization

A
  • Variation in which hydrogen peroxide is vaporized & reactive free radicals are produced
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25
Q

Plasma gas sterilization effectiveness

A
  • Reactive free radicals are produced with either microwave-frequency or radio-frequency energy
  • Efficient method that does not produce toxic by products
  • Anticipated to replace many of the applications for ethylene oxide
26
Q

Plasma gas sterilization cannot be used with

A
  • Materials that absorb hydrogen peroxide or react with it
27
Q

Spore test

A
  • Measures effectiveness of sterilization process
28
Q

Performing a spore test

A
  • Include ampule of spores in the processing
  • Incubate ampule at 37 degrees C
  • If process is successful, the organisms fail to grow in the culture from the ampule
29
Q

Difference between sterilization and disinfection

A
  • Some agents are used for both, but the concentration of the agent and duration of treatment varies
  • The types of agents that are used are determined by the nature of the material to be disinfected and how it will be used
30
Q

Hydrogen peroxide as a high-level disinfectant

A
  • Kills most bacteria at concentration of 3%-6%
  • Kills all organisms, including spores at higher concentration of 10%-25% (kills higher level of bacteria and non-enveloped viruses)
31
Q

Chlorine as a high-level disinfectant

A
  • Killing time dependent on concentration and temperature

- Spore-forming organisms are 10 to 1000 times more resistant to chlorine than vegetative bacteria

32
Q

Microbes

A
  • Also destroyed during disinfection, but some do survive
33
Q

Three levels of disinfection

A
  • High-level disinfectants
  • Intermediate-level disinfectants
  • Low-level disinfectants
34
Q

High-level disinfectants include

A
  • Moist heat
  • Glutaraldehyde
  • Hydrogen peroxide
  • Peracetic acid
  • Chlorine compounds
35
Q

Intermediate-level disinfectants include

A
  • Alcohols
  • Iodophor compounds
  • Phenolic compounds
36
Q

Low-level disinfectants include

A
  • Quaternary ammonium compounds
37
Q

When to use a high level disinfectant

A
  • If the material will be used for an invasive procedure, but cannot withstand sterilization procedures
  • Example: endoscopes cannot be autoclaved
38
Q

Peracetic acid

A
  • Oxidizing agent

- End products are acetic acid and oxygen (nontoxic)

39
Q

Glutaraldehyde

A
  • Can cause safety issues

- Special care in handling

40
Q

When to use an intermediate level disinfectant

A
  • To clean surfaces and instruments where contamination with highly resilient organisms is unlikely
41
Q

When to use low level disinfectants (mostly NH4)

A
  • To clean noncritical instruments and devices that do not go inside the body (blood pressure cuffs, electrodes, stethoscopes)
42
Q

Intermediate-level disinfectants (definition)

A
  • Germicide that kills microbial pathogens except spores
43
Q

Low-level disinfectants (definition)

A
  • Germicide that kills most vegetative bacteria and enveloped viruses
44
Q

Static activity (bacteriostatic, fungistatic)

A
  • Inhibits growth

- Incomplete killing

45
Q

Cidal activity (bactericidal, virucidal, sporocide, fungicidal)

A
  • Kills

- Irreverseible

46
Q

Disinfection

A
  • Kills most microorganisms on biologically inert surfaces

- Endospores killed, but some other pathogens may be resistance (tuberculosis)

47
Q

Disinfectants on tissues

A
  • Usually too toxic to be applied to tissues
48
Q

Sanitization

A
  • Reduces microorganism numbers to a predetermined acceptable level
  • Often similar to disinfection, but more tolerable to skin and other tissues
49
Q

Sanitization effectiveness

A
  • Some microorganisms may persist on sanitized surfaces

- Endospores generally survive procedure

50
Q

Iodine compounds as disinfectants

A
  • Precipitate proteins
  • Oxidize essential enzymes
  • Examples include tincture of iodine and povidone iodine (iodine complexed with polyvinylpyrrolidone)
51
Q

Chlorine compounds as disinfectants

A
  • Strong oxidizing agents
  • Most common commercial chlorine compound is bleach (5.25% sodium hypochlorite)
  • Usually diluted to 0.5% working strength
52
Q

Phenolic compounds (germicides) as disinfectants

A
  • Act by disrupting lipid-containing membranes
  • Results in leakage of cellular contents
  • Rarely used as disinfectants
  • Comparative standard for assessing other germicidal compounds
53
Q

Quaternary ammonium compounds as disinfectants

A
  • Denature cell membranes
  • Benzalkonium chloride
  • Cetylpyridinium chloride
54
Q

Sepsis

A
  • The presence of pathogenic organisms in tissue
55
Q

Antisepsis

A
  • Use of agents (antiseptics) to kill or inactivate microorganisms on anatomical surfaces
56
Q

Antiseptics compatible with human tissue

A
  • Alcohols
  • Iodophors
  • Chlorhexidine
  • Triclosan
57
Q

Alcohol as an antiseptic on human tissue

A
  • 70-90% concentration

- No residual activity

58
Q

Iodophor as an antiseptic on human tissue

A
  • Similar to alcohols

- Skin should be cleaned before using as organic matter on skin inactivates activity

59
Q

Chlorhexidine as an antiseptic on human tissue

A
  • Kills slower than alcohol, but activity persists
60
Q

Triclosan as an antiseptic on human tissue

A
  • Active against bacteria, but not other agents

- Used in soaps

61
Q

Fomites

A
  • Inanimate objects having come into contact with an infected individual or tissue
  • Capable of transmitting infectious agents (phones, computers, keys, etc.)

Medical Microbiology I (8 decks)

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