Controlling Microbial growth Flashcards
sterilization
the absolute removal or destruction of all microbial life and viruses
- All microorganisms must be eliminated
– Endospores are also removed
What is the term for the absolute removal or destruction of all microbial life and viruses, all microorganisms must be eliminated, Endospores are also removed
Sterilization
Disinfection
destruction of pathogenic microorganisms
Kills most but not all microbes
– Example: chemical disinfectants such as alcohol and bleach
What is the destruction of pathogenic microorganisms (disease causing), it Kills most but not all microbes
an example is: chemical disinfectants like alcohol and bleach
Disinfection
Antisepsis
disinfection of living tissue
- Requires less harsh of a chemical treatment
what is the disinfection of living tissue and it requires less harsh of a chemical treatment, and kills disease causing organisms
antisepsis
Degerming
removal of most microbes from a limited area
Example: swabbing a small area of skin with alcohol-mechanical removal
removal of most microbes from a limited area
an example is swabbing a small area of skin with alcohol-mechanical removal
Degerming (relocating the microbes)
Sanitization
lowering the microbial counts on a surface such that they are at a safe level
suffix ‘cide’
an agent that kills microbes has the suffic ‘cide’
Bacteriocidal
an agent that kills bacteria
Suffix ‘static’
An agent that stops the growth of microbes has the suffix ‘static’
bacteriostatic
an agent that stops the bacteria from reproducing
Asepsis
aseptic
- this is when an area is free of significant contamination
- Modern surgical technique occurs aseptically in order to minimize infection from operating personnel, instruments and the patient
list the physical methods of microbial control
- heat
- filtration
- air filtration
- low temperatures
- high Pressure
- Dessication
- Osmotic pressure
- Radiation
- Microwaves
Name the different types of heating methods for microbial control and the different subtypes in those types of methods
- Moist heat: boiling and Autoclave
- Pasteurization: HTST and UHT pasteurization
- Dry heat Sterilization: Direct flaming, Incineration, Hot air sterilization
Heat
– Kills microbes by destroying their fundamental enzymes
– Bacteriocidal
How does moist heat control microbes, what are the two types of moist heat?
A type of heating method for microbial control
includes: Boiling an autoclaves
1. Boiling: – Disrupts protein structure
– Breaks hydrogen bonds
– Boiling for 5 minutes kills:
» Most pathogens
» Most viruses
» Does not kill endospores
» Accomplishes disinfection
**2. Autoclave: **
– Uses 15psi of pressure and 121oC of steam
– Kills all endospores in about 15 minutes
– All organisms are also killed
– Best method for sterilization
– Used when heat damage is not a concern
– Used for culture media and hospital instruments
– Also used for hospital materials that are able to withstand heat and
moisture
– All liquids must reach 121oC
– This method requires that all physical surfaces are exposed to steam
Boiling
A type of Moist heat method for microbial control
– Disrupts protein structure
– Breaks hydrogen bonds
– Boiling for 5 minutes kills:
» Most pathogens
» Most viruses
» Does not kill endospores
» Accomplishes disinfection
Autoclave
what type of method is it?
What does it kill?
What is it used on?
What type of physical method is this?
Moist heat method for microbial control
– Uses 15psi of pressure and 121oC of steam
- All liquids must reach 121oC
– Kills all endospores in about 15 minutes, All organisms are also killed
Best method for sterilization, used when heat damage is not a concern
– Used for culture media and hospital instruments
– Also used for hospital materials that are able to withstand heat and moisture
– This method requires that all physical surfaces are exposed to steam
Pasteurization
Does not result in sterilization
- Eliminates pathogens and reduces microbial counts in order to slow spoilage
- Mild heating of a liquid
- Classic treatment is 63oC for 30 minutes
Alternative treatments include:
1) HTST Pasteurization
2) UHT Pasteurization
HTST pasteurization
-High temperature short-time
-72oC for 15 seconds
-Decreases the exposure time
-Most common today
UHT pasteurization
-Ultra-high temperature
-140oC for 3 seconds
-Can be stored without refrigeration
What is Dry Heat Sterilization and name the different subtypes for microbial control
Several methods
* Kill via oxidation
1. Direct Flaming:
* Used in the microbiology laboratory to sterilize inoculation needles and loops
* Metallic instruments must be red hot in order to be considered sterile
2. Incineration:
* An effective way to sterilize and
dispose of contaminated materials
* Paper cups, dressings
3. Hot Air Sterilization:
* Drying oven
* Materials should be kept at 170oC for 2 hours
* Ensures sterilization
* Used for dry materials that are not temperature sensitive
* Examples include: glassware, and some dry chemicals that are sensitive to moisture
Oxidation is used by what method
dry heat sterilization kill microbes through oxidation
Direct Flaming
A type of dry heat sterilization for microbial control
* Used in the microbiology laboratory to sterilize inoculation needles and loops
* Metallic instruments must be red hot in order to be considered sterile
A type of dry heat sterilization for microbial control
* Used in the microbiology laboratory to sterilize inoculation needles and loops
* Metallic instruments must be red hot in order to be considered sterile
Direct flaming
Incineration
A type of dry heat sterilization for microbial control
* An effective way to sterilize and dispose of contaminated materials
* Paper cups, dressings
A type of dry heat sterilization for microbial control
* An effective way to sterilize and dispose of contaminated materials
* Paper cups, dressings
Incineration
Hot Air Sterilization
A type of dry heat sterilization for microbial control
* Drying oven
* Materials should be kept at 170oC for 2 hours
* Ensures sterilization
* Used for dry materials that are not temperature sensitive
* Examples include: glassware, and some dry chemicals that are sensitive to moisture
- Drying oven
- Materials should be kept at 170oC for 2 hours
- Ensures sterilization
- Used for dry materials that are not temperature sensitive
- Examples include: glassware, and some dry chemicals that are sensitive to moisture
Hot air sterilization
Filtration
Vacuum is used to force liquid through a filter with
very small pores: 0.10μm, 0.22μm, or 0.45 μm
* Pores are too small for bacteria to pass through
* Used to sterilize temperature sensitive liquids
* Antibiotics
* Enzymes
* Some vaccines
* Culture media
* viruses are much smaller than bacteria and
are able to pass through the pores
Vacuum is used to force liquid through a filter with
very small pores: 0.10μm, 0.22μm, or 0.45 μm
* Pores are too small for bacteria to pass through
* Used to sterilize temperature sensitive liquids
* Antibiotics
* Enzymes
* Some vaccines
* Culture media
* viruses are much smaller than bacteria and
are able to pass through the pores
Filtration
Air Filtration
- High Efficiency Particulate Air (HEPA) Filters
- Filter air
- Used in some operating rooms to remove all microbes larger than 0.30μm in
diameter - Also used in rooms of burn patients
- High Efficiency Particulate Air (HEPA) Filters
- Filter air
- Used in some operating rooms to remove all microbes larger than 0.30μm in
diameter - Also used in rooms of burn patients
Low Temperatures
Refrigeration: slows or stops microbial growth
* Bacteriostatic
* Freezing stops microbial growth
* Only a small portion of microbes will die
* Reduces metabolic rate
* No reproduction or toxin synthesis
Refrigeration: slows or stops microbial growth
* Bacteriostatic
* Freezing stops microbial growth
* Only a small portion of microbes will die
* Reduces metabolic rate
* No reproduction or toxin synthesis
Low temperatures
High Pressure
- Liquid suspensions are treated with high pressure
- Disturbs protein/molecular structure
- Kills most bacterial cells
- Bacteriocidal
- Doesn’t kill endospores
- Not sterilization
- Liquid suspensions are treated with high pressure
- Disturbs protein/molecular structure
- Kills most bacterial cells
- Bacteriocidal
- Doesn’t kill endospores
- Not sterilization
high pressure
Dessication
- Used to control microbial growth
- Bacteriostatic
- Removal of water (drying)
- Slows or stops microbial growth but does not kill microbes
- Microbes can remain viable for years in a dehydrated state
- Used to control microbial growth
- Bacteriostatic
- Removal of water (drying)
- Slows or stops microbial growth but does not kill microbes
- Microbes can remain viable for years in a dehydrated state
dessication
Osmotic Pressure
- High concentrations of salts and sugars creates a hypertonic
environment, bacterial cell will dehydrate and shrivel - Can kill some bacteria therefore it is both bacteriocidal and
bacteriostatic - Molds and yeasts are more resistant
Radiation
- Destroys DNA
- X-rays and gamma rays penetrate materials
- UV and high energy electron beams are
used on surfaces
Microwaves
- Use longer wavelengths
- Not of high enough energy to kill the organism directly
- Do not directly kill microorganisms
- The microwaves heat the water which then kills the microorganisms
- The high temperatures created by the microwaves are used to disinfect
materials
- Used to control microbial growth
- Bacteriostatic
- Removal of water (drying)
- Slows or stops microbial growth but does not kill microbes
- Microbes can remain viable for years in a dehydrated state
dessication
Vacuum is used to force liquid through a filter with
very small pores: 0.10μm, 0.22μm, or 0.45 μm
* Pores are too small for bacteria to pass through
* Used to sterilize temperature sensitive liquids
* Antibiotics
* Enzymes
* Some vaccines
* Culture media
* viruses are much smaller than bacteria and
are able to pass through the pores
Filtration
