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Fundamentals of MLS > Sterilization and Disinfection > Flashcards

Sterilization and Disinfection Flashcards

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1
Q

What is decontamination?

A

Procedures that remove contamination by killing microorganisms, rendering the items safe for disposal or use.

Necessary for infection control.

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2
Q

What is sterilization and disinfection in general?

A

Destroy or inhibit growth of microorganism.

Sterilization and disinfection each represent different levels of decontamination.

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3
Q

What is sterilization?

A

Destroys all microbial life.

E.g. parasites, fungi, bacteria (including spores) and viruses.

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4
Q

What is disinfection?

A

Eliminates virtually all pathogens but NOT ALL.

E.g. bacterial spores may be able to survive.

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5
Q

What does the suffix -cidal mean in reference to an agent?

A
  • cidal
    Means death, indicates microorganism being killed.

E.g. Bactericidal, fungicidal, etc.

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6
Q

What does the suffix -static mean?

A
  • static
    Means being halted; indicates microorganism can no longer grow, but is NOT killed.

E.g. Bacteriostatic, fungistatic.

Refer to Slide 5 diagram.

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7
Q

When should something be sterile?

A
  1. Equipment or devices that come into contact with tissue
  2. Equipment used to transport specimens
  3. Specimens or materials prior to disposal
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8
Q

What are three categories of sterilization?

A

Three categories used in health care setting:

  1. Incineration
  2. Autoclave
  3. Chemical disinfectants
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9
Q

What occurs in incineration?

A

Burn to ashes at very high temperatures.
Emissions monitored for hazardous chemicals.

All microorganisms are killed and only a small amount of ash is left.

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10
Q

What is “terminal sterilization”?

A

Method of disposing of items using incineration.

Note: terminal sterilization the final sterilization of instruments and equipment following use, thereby rendering them safe for handling. Source: online medical dictionary.

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11
Q

Do hospitals have their own incinerator?

A

Some do and some package and label waste for incineration at a a commercial site.

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12
Q

What type of items could be incinerated?

A 
Used needles and syringes
Intravenous sets
Used gloves
Discarded bandages
Discarded laboratory cultures
Blood samples
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13
Q

What gas is used for heat sensitive sterilization?

A

Ethylene oxide

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14
Q

What are the pros and cons of a ETO sterilizer (Ethylene oxide)?

A 
ETO Sterilizer
1. Pros:
Walk-in types
Large loads at one time
8 hours followed by a 24 hour room temp wait for ETO to dissipate
2. Cons:
Slow and expensive
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15
Q

What are other forms of sterilization?

A
  1. Filtration: Removes microorganisms from liquid. Pore size 0.2υm
  2. Dry heat
  3. Boiling
  4. Radiation: Damages DNA by causing mutations. UV light, X-rays, Gamma rays
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16
Q

List the various types of chemical disinfectants that can be used.

A 
Detergents and soaps
Alcohols
Chlorine-containing
Iodophores
Complex phenolic compounds
Gluteraldehyde
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17
Q

What is a surface active agents?

A

Decrease surface tension between molecule and surface

Detergents are better than soaps

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18
Q

How do quaternary ammonium compounds work for disinfecting?

A

Quaternary ammonium compounds
How do they work?
1. Detergents with a positive charge = cationic detergents
2. Cause cell membrane disruption in g+ bacteria, fungi, and lipid viruses

Considered a low level disinfectant

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19
Q

What is Quaternary ammonium compounds

disinfectants used for? Name an example.

A

Used to disinfect surfaces and skin antisepsis

Example: Zephiran

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20
Q

What are the advantages of quaternary ammonium compounds as disinfectants?

A 
Economical
No unpleasant odor or taste
Non-irritating to tissue
Good wetting agent 
Kills g+ bacteria
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21
Q

What are the disadvantages of quaternary ammonium compounds as a disinfectant?

A

Narrow antimicrobial spectrum
Inactivated by soaps, detergents, fibers, hard water, and organic material
G- bacteria can grow in the disinfectant

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22
Q

What two alcohols are used for disinfection?

A

Only two alcohols used for disinfection

  1. Ethyl alcohol (ethanol)
  2. Isopropyl alcohol (isopropanol)
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23
Q

What concentration do the alcohols need to be to work as a disinfectant?

A

Need to be in concentrations between 50 – 80%

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24
Q

How do the alcohols work to act as a disinfectant?

A

Denature and coagulate microbial protein = death

Penetrate lipid viruses and tubercle bacilli well

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25
What are alcohols used for in disinfecting?
Low level disinfectant Used for antisepsis Evaporate quickly
26
What are the advantages of alcohol used as a disinfectant?
1. Economical 2. Very little irritation to human tissue 3. Ability to kill bacteria, lipid-viruses, and tubercle bacilli
27
What are the disadvantages of alcohol using it as a disinfectant?
1. Antimicrobial action diminishes with heavy microbial load and organic material 2. Does not kill spores and non-lipid viruses 3. Rapid evaporation 4. Flammable
28
What is chlorine in water called and how does it disinfect?
Chlorine in water = hypochlorous acid | Potent oxidizing agent = rapidly kills microorganisms
29
How is concentration of hypochlorite expressed?
``` Concentration expressed as ppm - Parts per million Percent of hypochlorite as a dilution - Refers to the dilution of household bleach Usually at 5.0% or 50 000 ppm ```
30
At what level (conc.) is blood considered contaminated with hypochlorous acid compared to the concentration used for cleaning?
Blood contamination = 1/10 (5000ppm) | Routine cleaning = 1/100 (500ppm)
31
Why should bleach be diluted daily?
Chlorine escapes into atmosphere - ->Reducing amount in solution - ->Reducing its ability to disinfect
32
What bleach concentration (chlorine containing) should be used for a) spills b) wiping benches?
1/10 – used for spills 10mL bleach + 90mL of water 1/100 – wiping benches 1mL bleach + 99mL of water
33
What are the advantages of chlorine based disinfectants?
1. Economical and readily available 2. Rapid action 3. Kills tubercle bacilli and viruses 4. Effective in diluted solutions
34
What are the disadvantages of chlorine based disinfectants?
1. Corrosive to metal and degrades plastics 2. Must be diluted daily 3. Unpleasant odor 4. Irritating to skin and eyes 5. Inactivated by organic matter 6. Only sporicidal at high concentrations 7. Can bleach clothes if spilled
35
What level of disinfectant is iodine?
Intermediate level disinfectant
36
Name some examples of iodine disinfectants used for antisepsis.
Examples: Betadine and Prepodyne
37
Describe the spectrum of 'bugs' killed with iodine disinfectants?
Kills a wide antimicrobial spectrum | Vegetative bacteria, tubercle bacilli, fungi, most viruses, and some bacterial spores
38
What type of iodine disinfectant is used in healthcare?
In health care use iodophore | Solution of iodine and a carrier molecule
39
What are advantages of iodophores?
1. Economical and may be diluted for use 2. Broad spectrum 3. Kills in ten minutes 4. Good cleaning agent when coupled with detergent 5. Some residual action when allowed to build up on a surface
40
What disadvantages of iodophores?
1. Must be diluted daily and not diluted with hard water 2. Discoloration of some materials such as plastic 3. Allergies
41
What are phenolic compounds used for as a disinfectant?
Anitsepsis Examples include: Cresols and Lysol = phenols with other disinfectants Less toxic when altered like that
42
What does phenolic compounds kill?
Kills g+ and g- bacteria, non-lipid viruses
43
What level of a disinfectant is phenolic compounds considered?
Intermediate disinfectant | Some residual activity
44
Historically, what was hexachlorophene once used for (type of phenolic compound) and what was the result?
Hexachlorophene: 1. In the 60’s and 70’s used to bathe babies 2. Discovered to be toxic 3. Absorbed through skin and caused brain damage and even death
45
What are the advantages of phenolic compounds?
Economical No offensive odor Can be used on skin Effective against many microorganisms
46
What are the disadvantages of using phenolic compounds as disinfectants?
Does not kill spores | Toxicity to some body tissues
47
What is glutaraldehyde and what is it used for as a disinfectant?
Belongs to aldehyde group Used for surface disinfection Most widely used = Cidex 14 day shelf life
48
What are the differences between glutaraldehyde products?
Differences between Glutaraldehyde products: 1. Shelf life; vary between 14 – 45 days 2. Should be made fresh every day 3. pH of solution; acid to alkaline 4. Length of time required to kill various microbes
49
What are the advantages of glutaraldehyde | as a disinfectant?
1. Broad antimicrobial spectrum 2. Does not destroy rubber and plastic 3. Not inactivated by blood and body secretions
50
What are the disadvantages of glutaraldehyde as a disinfectant?
1. Expensive 2. Toxic to skin and mucous membranes 3. Fumes are irritating 4. Shelf life after activation must be adhered to
51
What is formaldehyde and its uses as a disinfectant?
1. Belongs to aldehyde group 2. Used to clean HEPA filters in BSC 3. Available as solid paraformaldehyde and liquid formalin
52
What are the advantages of formaldehyde as a disinfectant?
Broad antimicrobial spectrum | Does not destroy rubber and plastic
53
What are the disadvantages of formaldehyde as a disinfectant?
Extremely toxic Fumes are irritating Known carcinogen More susceptible to inactivation by organic material than gluteraldehyde
54
What are the characteristics of peroxides as a disinfectant?
Weak acid | Strong Oxidizer
55
Name some examples of peroxides as a disinfectant.
Hydrogen peroxide. | Perdiem
56
What are the advantages of peroxides used as a disinfectant?
``` Wide Spectrum 6% - short contact time (higher concentrations or longer time for spores) Easy to find Inexpensive Relatively safe ```
57
What are the disadvantages of peroxides used as a disinfectant?
May be unstable when exposed to heat and light High conc. may burn skin, irritate mucous membranes Can pose a risk of explosion
58
What are some mechanical methods of disinfection?
Mechanical: 1. Pasteurization - Used for respiratory tubing - 30 minutes at 63°C - Intermediate level of disinfection = no spore killing 2. Filtration - Membrane, HEPA
59
How do you use disinfectants to treat a biohazard spill?
Spill: 1. Notify co-workers 2. Apply PPE 3. Cover with paper towel 4. Pour disinfectant on it (10% Bleach) 5. Wait 30 minutes 6. Wipe area of residue
60
What can labs do with leaking specimens?
Many labs now refuse to accept leaking specimens. Exception, where a new sample cannot be obtained, it may be decided to process sample
61
What is a procedure to follow if there is a leaking specimen?
1. Inform others if leaking everywhere 2. PPE 3. Place in tray in a large plastic zip lock bag and move to BSC 4. Treat as spill if leaked on counter top 5. Transfer specimen to a clean container (label) 6. If requisition contaminated, lay it flat in a plastic bag and later copy information onto new clean requisition. 7. Flood tray, and contents with disinfectant; leave several hours

Fundamentals of MLS (18 decks)

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