Ex. 2 - Sterilization and Disinfection Flashcards
It is a process of complete elimination or destruction of all forms of microbial life, both vegetative and spore forms. (spore-forming and nonspore-forming)
Sterilization
It is a process of complete elimination of vegetative forms of microorganisms except the bacterial spores from inanimate objects. (vegetative and nonspore-forming)
Disinfection
It is the process of removal of pathogenic microorganisms from objects so that they are safe to handle.
Decontamination
It is defined as the removal of visible soil (e.g., organic and inorganic materials) from the surfaces and objects.
Cleaning
It is the process of removal of germs from the skin.
Antisepsis (disinfection of living tissue or removal of transient microbe from the skin)
These are test systems containing viable microorganisms providing a defined resistance to a specific sterilization process.
Biological indicators
Commonly used as biological indicators owing to their high resistance to environmental stresses including sterilization process.
Endospores or bacterial spores
This is a thermophilic bacteria with an optimum growth temperature range of 55 and 60 degrees Celsius. The spores demonstrate a high resistance toward steam and vaporized hydrogen peroxide.
Geobacillus stearothermophilus
This is a mesophilic organism with an optimum growth temperature range of 30 to 39 degrees Celsius. Intended for ethylene oxide, dry heat, and ozone sterilization processes.
Bacillus atrophaeus
Physical Sterilization Methods
Heat, Filtration, Ionizing Radiation
Under heat, what are the two types and what are they for?
- Moist heat - coagulates protein
2. Dry heat - kills by oxidation
Under moist heat, there are two, what are those?
- Autoclave
2. Fractional
What is fractional heating? What are the two types?
It is the alternate heating (vegetative cells), incubation (spores germinate), and heating (remaining).
> Tyndallization - flowing steam of 100 degrees for 30 minutes for 3 successive days
Inspissation - 75 to 80 degrees Celsius for 2 hours for 3 successive days
What are the 3 types under dry heat?
- Flame
- Oven
- Incineration
When is flame used?
To sterilize inoculating loops and needles
When is oven used?
For glass wares, certain metals, oil, petrolatum, or powders at 160 to 180 degrees Celsius for 1 1/2 to 2 hours with a quality control tester of Bacillus atrophaeus
This is the most common method of treating infectious waste that uses 870 to 980 degrees Celsius.
Incineration
This is the method of choice for antibiotic solutions, toxic chemicals, radioisotopes, vaccines, and carbohydrates, which are heat-sensitive materials. Also for urea broth and sugar fermentation broth
Filtration
T or F: Filtration of liquids can be accomplished by pulling the solution through a cellulose acetate or cellulose nitrate membrane with a vacuum.
True
This method makes use of short wavelength but high energy gamma rays for sterilizing plastic syringes, catheter or gloves.
Ionizing radiation
This is the most common chemical sterilant that is used in cold sterilization with strict requirements of concentration and humidity. It is also used for materials which cannot be autoclaved. (Quality control: Bacillus atrophaeus)
Ethylene oxide (ETO)
Used to sterilize HEPA filters in biological safety cabinets
Formaldehyde vapor and vapor phase hydrogen peroxide
Used for cold sterilization and is sporicidal (kills spores) in 3 to 10 hours which is used for medical equipment such as bronchoscopes, because it does not corrode lenses, metal, or rubber.
Glutaraldehyde
Cold sterilization that is effective in the presence of organic material, and has been used for the surface sterilization of surgical instruments.
Peracetic acid
Physical Disinfection Methods
- Boiling
- Pasteurization
- Non-ionizing radiation
100 degrees Celsius for 15 minutes to kill vegetative bacteria
Boiling
Used mostly in food industry, eliminates food-borne pathogens and organisms responsible for food spoilage.
Pasteurization
Two types of Pasteurization
- Batch method - 63 degrees for 30 minutes
2. Flash method - 72 degrees for 15 seconds
Uses long wavelength, low energy radiation (between 250-300 nm)
Non-ionizing radiation
Chemicals used to destroy all life are called ________?
Chemical sterilants or biocides
Disinfectants used on living tissue (skin) are called ______?
Antiseptics
Destroys vegetative forms on inanimate objects (microbicidal). Examples include phenol, phenolics, QUATS, chlorine, 2% aq. glutaraldehyde.
Disinfectants
Microbiostatic agents used on living tissues. Examples include alcohol, tincture (alcoholic) iodine, iodophor.
Antiseptic
Denatures proteins; make lipids soluble. Use is limited to the skin as an antiseptic or on thermometers and injection vial rubber septa as a disinfectant.
Alcohol
T or F: 70% ethyl alcohol is more effective as a disinfectant than 95% ethyl alcohol because the increased water hydrolyzing bonds in protein molecules make the killing of microorganisms more effective.
True
Disinfectants that kills endospores. Also, toxic to humans.
Aldehydes (in solution) - formaldehyde 8%, glutaraldehyde 2%
Halogens
Iodine and chlorine are the frequently used as disinfectant.
Iodine - prepared either as a tincture with alcohol or as an iodophor (iodine + detergent chlorine) coupled to a neutral polymer.
70% ethyl alcohol followed by an iodophor, is the most common compound used for skin disinfection.
Chlorine is most often used in the form of sodium hypochlorite (NaOCl) as household bleach.
Heavy metals
Heavy metals containing mercury are no longer recommended since it is toxic.
Eye drop solution containing 1% silver nitrate is still placed in the eyes of newborns to prevent infections with N. gonorrhoeae.
Quaternary ammonium compounds (QUATS)
Low toxicity and is used to disinfect bench tops or other surfaces.
Rapidly inactivated by organic matter.
Benzalkonium chloride (Zephiran)
Phenolics
Denature proteins; disrupt cell membranes
Disinfectants at high concentrations; used in soaps at low concentrations
