Lecture #6 Flashcards
What does sterilization mean?
The absolute removal or destruction of all microbial life and viruses
In sterilization, are all microorganisms eliminated? Endospores?
All microorganisms are eliminated including endospores
What does it mean to disinfect?
Destruction of pathogenic microorganisms
Does disinfection kill all microorganisms?
Most but not all
What are two examples of chemical disinfectants?
Chemical and bleach
What does antisepsis?
Disinfection of living tissue
What does degerming mean?
Removal of most microbes from a limited area
What is an example of mechanical removal?
Swabbing a small area of skin with alcohol
What does sanitization do?
Lower the microbial counts on a surface such that they are at a safe level
The suffix ‘cide’ means?
An agent that kills microbes
A bacterial agent kills…?
Bacteria
The suffix ‘static’ means?
An agent that stops the growth of microbes
A bacteriostatic agent stops…?
the bacteria from reproducing (holds bacteria numbers constant)
What does it mean when an area is asepsis (aseptic)
An area is free of significant contamination
Modern surgical technique occurs ______ in order to minimize infection from operating personal, instruments and the patient
Aseptically
How does heat control microbial growth?
Kills microbes by destroying their fundamental enzymes
Moist heat is very effective at destroying what kind of bonds?
Hydrogen bonds
Boiling for 5 minutes would do what to pathogens? Viruses? Endospores? Would it be considered disinfecting?
Pathogens- Kill most
Viruses- Kill most
Endospores- Does not kill
Accomplishing disinfection
An autoclave can only be used for things that…?
Can handle high heat
How does an autoclave work?
Uses 15psi of press and 121 degree of steam
Does an autoclave kill endospores? What about other organisms?
Yes in 15 minutes, kills all other organisms
What is the best method for sterilization?
An autoclave
What are some examples of real life uses for autoclaves
- Culture media
2. Hospital Instruments
For an autoclave to be affective what must work?
All liquids must reach 121 degrees and all physical surfaces must be exposed to steam
What does pasteurization do?
Eliminates pathogens and reduces microbial counts in order to slow spoilage
What is the classic pasteurization treatment?
63 degrees for 30 minutes
What are two alternative pasteurization treatments?
High temp in short time (HTST)
Ultra-high temperature (UHT)
What is the treatment for HTST? UHT?
HTST- 72 degree for 15 seconds
UHT- 140 degree for 3 seconds
What is the most common pasteurization technique called?
high temperature in short time
What type of pasteurization technique does the item not need to be refrigerated anymore?
UHT
Dry Heat Sterilization kills via….?
oxidation
What is direct flame sterilization used for?
In microbio laboratory to sterilize inoculation needs and loops
What way of sterilization is the most effective for sterilizing and disposing of contaminated materials?
Incineration
What is the procedure for hot air sterilization? How hot for how long?
In a drying oven, materials must be kept at 170 degrees for two hours to ensure sterilization
What type of materials can be sterilized in a hot air sterilizer?
Dry materials not temperature sensitive. e.g.. glassware, dry chemicals sensitive to moisture
How does filtration work for sterilization?
Vacuum is used to force liquid through a filter with very small pores
How does filtration keep bacteria out?
Pores are too small for bacteria to pass through
What type of material would filtration be used for?
To sterilize temperature sensitive liquids (antibiotics, enzymes, some vaccines and culture media)
Bacteria are not able to pass through filtration but what is?
Viruses because they are much smaller
Air filtration uses what type of filters?
High Efficiency Particulate Air (HEPA)
Where is air filtration used?
Some operating rooms and rooms of burn victims
Does low temperature kill all bacteria?
No
Are low temps bacteriostatic or bactericidal?
Bacteriostatic
Is high pressure bactericidal or bacteriostatic?
Bactericidal
How does high pressure work to kill bacteria?
Liquid suspicions are treated with high pressure. The pressure disturbs protein/molecular structure
Does high pressure kill all bacteria?
Most
Does high pressure kill endospores?
No because its not sterilization
Is desiccation bacteriostatic or bactericidal?
Bacteriostatic- used to control microbial growth
What does desiccation do to microbes? Why doesn’t it kill them?
Removes the water. Does not kill microbes because they can remain viable for 6 years without water
How is osmotic pressure used to kill bacteria?
High concentrations of salts and sugars are used to create a hypertonic environment, therefore bacterial cell will dehydrate and shrivel
Does osmotic pressure kill all bacteria?
Some (both bacteriostatic and bactericidal)
What is more resistant to osmotic pressure?
Molds and yeast
How does radiation effect DNA
It destroys it
Can microwaves kill microorganisms directly?
No, there is not a high enough energy
What is sterilization?
Reducing microbial level counts to a safe level
How are disinfectants evaluated for effectiveness?
The disk diffusion method
How does the disk diffusion method work?
- A disk of filter paper is soaked in a chemical disinfectant
- Disk is placed on agar plate that has already been inoculated with bacteria
- Chemical will diffuse form the paper to the plate
- The plate is incubated until the inoculated bacteria grow
- The zone of clearance around the bacteria is used to determine the effectiveness of the disinfectant
What do phenolics and bisphenols do to a bacteria?
Disrupts the plasma membranes and denatures proteins
Are phenolics and bisphenols bacteriostatic or bactericidal?
Bactericidal
How effective are phenolics and bisphenols?How long do they stay active for?
Very effective and remain active long after application
What type of surfaces are phenolics and bisphenols used to disinfect?
Those that are contaminated with saliva, pus and feces
What is an example of a phenolic
Lysol
What are two examples of bisphenols and what are they used for?
- Hexachlorophene- useful against bacteria that cause skin infections in newborns (to disinfect nurseries)
- Triclosan- used in some personal hygiene products and cosmetics
How do biguanides work for sterilization?
attacks the plasma membrane
What are two things that biguanides are used for?
Control microbes on the skin and mucous membrane
Used in surgical hang scrubs
Is biguanides bacteriostatic or bactericidal?
Bactericidal
How long can biguanides last?
up to 6 hours
What does biguanides kill/ not kill?
Only kills enveloped viruses.
Does not kill non enveloped or endospores
Mycobacteria are also very resistant
What are two examples of halogens?
Chlorine and Iodine
What do halogens do to sterilize?
Impair protein synthesis and alter membranes
What does chlorine destroy, what type of strong agent is it?
Strong oxidizing agent, destroys enzymes
What are two ways in which iodine is available?
Tincture or iodophore
What is a tincture?
in a solution in aqueous alcohol
What is an iodophore?
A combination of iodine and an organic molecule
What is an example of an iodine and what is it used for?
Betadine- used as an antiseptic on skin
What does alcohol do to a bacteria?
Denatures proteins and disrupts liquid membranes
What does alcohol kill? What can it not kill?
Kills Bacteria and fungi
Does not kill- endospores and non enveloped viruses
What is the most effective type of alcohol?
Ethanol 70%
What are the two most common alcohols used?
Ethanol and Isopropanol (rubbing alcohol)
What do heavy metals do for microbes?
They can inhibit microbes
What is silver nitrate (1%) used for? What is an example?
As an antiseptic
Eyedrops for newborns to protect against gonorrhoea of the eye
What is silver sulfadiazine used for?
Topical cream for burns
What can silver ions be used for?
Can be incorporated into dressings and catheters to prevent hospital acquired infections
What can copper sulphite be used for?
To destroy green algae that lives in swimming pools and fish tanks
What type of metal has been used in mouth washes?
Zinc Chloride
Do soap and detergents work as antiseptics?
No, they work as a surface agent
How do soap and detergents work for removing microbes?
Soap breaks up oil that is present on skin and the water washes the oil and debris away
What is a good determining agent?
Soap and water
What do Quaternary Ammonium Compounds do? What type of detergent are they?
Cationic detergents
Kill most bacteria, fungi and some viruses
What does Quaternary Ammonium Compounds not kill?
Endospores and mycobacterium
Quaternary Ammonium Compounds are less effective against ______ than _______
gram negative, gram postive
What does Quaternary Ammonium Compounds do to the bacteria to kill it?
Effects the plasma membrane
What is an example of a Quaternary Ammonium Compound?
Cepecol: used as a mouthwash
What can survive and thrive in Quaternary Ammonium Compounds?
Pseudomonas (thrive on the weak)
What is a gaseous chemosterilizer? Example?
Chemical gases used for sterilization
Ethylene Oxide
What does chemosterilizers do to affect the bacteria?
Denatures proteins
Are chemosterilizers bactericidal or bacteriostatic?
Bactericidal
What can chemosterilizers kill?
All microbes including endospores and viruses
How long does chemosterilization take? What can it be used to sterilize?
4-18 hours
Sterilize disponible hospital equipment and lab supplies
What do oxidizing agents do to the bacteria?
Oxidize (take away electrons) and denatures proteins
What type of organisms can oxidizing agents be useful for?
Anaerobic organisms
What are 3 examples of oxidizing agents and what are they used for?
- Hydrogen peroxide- common antiseptic for wounds
- Ozone- used with chlorine to disinfect water
- Benzoyl Peroxide- used as an antiseptic on skin
How does benzoyl peroxide work? example?
Kill anaerobic bacteria living in tissues
Ex. bacteria that cause once
