Sterilization and Disinfection Flashcards
What is decontamination?
Procedures that remove contamination by killing microorganisms, rendering the items safe for disposal or use.
Necessary for infection control.
What is sterilization and disinfection in general?
Destroy or inhibit growth of microorganism.
Sterilization and disinfection each represent different levels of decontamination.
What is sterilization?
Destroys all microbial life.
E.g. parasites, fungi, bacteria (including spores) and viruses.
What is disinfection?
Eliminates virtually all pathogens but NOT ALL.
E.g. bacterial spores may be able to survive.
What does the suffix -cidal mean in reference to an agent?
- cidal
Means death, indicates microorganism being killed.
E.g. Bactericidal, fungicidal, etc.
What does the suffix -static mean?
- static
Means being halted; indicates microorganism can no longer grow, but is NOT killed.
E.g. Bacteriostatic, fungistatic.
Refer to Slide 5 diagram.
When should something be sterile?
- Equipment or devices that come into contact with tissue
- Equipment used to transport specimens
- Specimens or materials prior to disposal
What are three categories of sterilization?
Three categories used in health care setting:
- Incineration
- Autoclave
- Chemical disinfectants
What occurs in incineration?
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.
What is “terminal sterilization”?
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.
Do hospitals have their own incinerator?
Some do and some package and label waste for incineration at a a commercial site.
What type of items could be incinerated?
Used needles and syringes Intravenous sets Used gloves Discarded bandages Discarded laboratory cultures Blood samples
What gas is used for heat sensitive sterilization?
Ethylene oxide
What are the pros and cons of a ETO sterilizer (Ethylene oxide)?
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
What are other forms of sterilization?
- Filtration: Removes microorganisms from liquid. Pore size 0.2υm
- Dry heat
- Boiling
- Radiation: Damages DNA by causing mutations. UV light, X-rays, Gamma rays
List the various types of chemical disinfectants that can be used.
Detergents and soaps Alcohols Chlorine-containing Iodophores Complex phenolic compounds Gluteraldehyde
What is a surface active agents?
Decrease surface tension between molecule and surface
Detergents are better than soaps
How do quaternary ammonium compounds work for disinfecting?
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
What is Quaternary ammonium compounds
disinfectants used for? Name an example.
Used to disinfect surfaces and skin antisepsis
Example: Zephiran
What are the advantages of quaternary ammonium compounds as disinfectants?
Economical No unpleasant odor or taste Non-irritating to tissue Good wetting agent Kills g+ bacteria
What are the disadvantages of quaternary ammonium compounds as a disinfectant?
Narrow antimicrobial spectrum
Inactivated by soaps, detergents, fibers, hard water, and organic material
G- bacteria can grow in the disinfectant
What two alcohols are used for disinfection?
Only two alcohols used for disinfection
- Ethyl alcohol (ethanol)
- Isopropyl alcohol (isopropanol)
What concentration do the alcohols need to be to work as a disinfectant?
Need to be in concentrations between 50 – 80%
How do the alcohols work to act as a disinfectant?
Denature and coagulate microbial protein = death
Penetrate lipid viruses and tubercle bacilli well
What are alcohols used for in disinfecting?
Low level disinfectant
Used for antisepsis
Evaporate quickly
What are the advantages of alcohol used as a disinfectant?
- Economical
- Very little irritation to human tissue
- Ability to kill bacteria, lipid-viruses, and tubercle bacilli
What are the disadvantages of alcohol using it as a disinfectant?
- Antimicrobial action diminishes with heavy microbial load and organic material
- Does not kill spores and non-lipid viruses
- Rapid evaporation
- Flammable
What is chlorine in water called and how does it disinfect?
Chlorine in water = hypochlorous acid
Potent oxidizing agent = rapidly kills microorganisms
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
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)
Why should bleach be diluted daily?
Chlorine escapes into atmosphere
- ->Reducing amount in solution
- ->Reducing its ability to disinfect
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
What are the advantages of chlorine based disinfectants?
- Economical and readily available
- Rapid action
- Kills tubercle bacilli and viruses
- Effective in diluted solutions
What are the disadvantages of chlorine based disinfectants?
- Corrosive to metal and degrades plastics
- Must be diluted daily
- Unpleasant odor
- Irritating to skin and eyes
- Inactivated by organic matter
- Only sporicidal at high concentrations
- Can bleach clothes if spilled
What level of disinfectant is iodine?
Intermediate level disinfectant
Name some examples of iodine disinfectants used for antisepsis.
Examples: Betadine and Prepodyne
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
What type of iodine disinfectant is used in healthcare?
In health care use iodophore
Solution of iodine and a carrier molecule
What are advantages of iodophores?
- Economical and may be diluted for use
- Broad spectrum
- Kills in ten minutes
- Good cleaning agent when coupled with detergent
- Some residual action when allowed to build up on a surface
What disadvantages of iodophores?
- Must be diluted daily and not diluted with hard water
- Discoloration of some materials such as plastic
- Allergies
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
What does phenolic compounds kill?
Kills g+ and g- bacteria, non-lipid viruses
What level of a disinfectant is phenolic compounds considered?
Intermediate disinfectant
Some residual activity
Historically, what was hexachlorophene once used for (type of phenolic compound) and what was the result?
Hexachlorophene:
- In the 60’s and 70’s used to bathe babies
- Discovered to be toxic
- Absorbed through skin and caused brain damage and even death
What are the advantages of phenolic compounds?
Economical
No offensive odor
Can be used on skin
Effective against many microorganisms
What are the disadvantages of using phenolic compounds as disinfectants?
Does not kill spores
Toxicity to some body tissues
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
What are the differences between glutaraldehyde products?
Differences between Glutaraldehyde products:
- Shelf life; vary between 14 – 45 days
- Should be made fresh every day
- pH of solution; acid to alkaline
- Length of time required to kill various microbes
What are the advantages of glutaraldehyde
as a disinfectant?
- Broad antimicrobial spectrum
- Does not destroy rubber and plastic
- Not inactivated by blood and body secretions
What are the disadvantages of glutaraldehyde as a disinfectant?
- Expensive
- Toxic to skin and mucous membranes
- Fumes are irritating
- Shelf life after activation must be adhered to
What is formaldehyde and its uses as a disinfectant?
- Belongs to aldehyde group
- Used to clean HEPA filters in BSC
- Available as solid paraformaldehyde and liquid formalin
What are the advantages of formaldehyde as a disinfectant?
Broad antimicrobial spectrum
Does not destroy rubber and plastic
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
What are the characteristics of peroxides as a disinfectant?
Weak acid
Strong Oxidizer
Name some examples of peroxides as a disinfectant.
Hydrogen peroxide.
Perdiem
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
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
What are some mechanical methods of disinfection?
Mechanical:
- Pasteurization - Used for respiratory tubing
- 30 minutes at 63°C
- Intermediate level of disinfection = no spore killing - Filtration - Membrane, HEPA
How do you use disinfectants to treat a biohazard spill?
Spill:
- Notify co-workers
- Apply PPE
- Cover with paper towel
- Pour disinfectant on it (10% Bleach)
- Wait 30 minutes
- Wipe area of residue
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
What is a procedure to follow if there is a leaking specimen?
- Inform others if leaking everywhere
- PPE
- Place in tray in a large plastic zip lock bag and move to BSC
- Treat as spill if leaked on counter top
- Transfer specimen to a clean container (label)
- If requisition contaminated, lay it flat in a plastic bag and later copy information onto new clean requisition.
- Flood tray, and contents with disinfectant; leave several hours
