Control of Microbial Growth I Flashcards
Who revolutionized surgery by introducing methods to prevent infection of wounds
Joseph Lister
Sterilization
kills ALL microbes including endospores (does not consider prions)
T/F sterilization kills prions
False
Disinfection
Removal of almost all microbial life forms except endospores
What are two ways to preform disinfection
disinfectants: cleans surfaces
antiseptics: cleans skin, milder than disinfectants
What is pasteurization
Brief heating to reduce the number of spoilage organisms, destroys pathogens
Why isn’t pasteurization a form of sterilization
because it is only reducing microbes, never ever free of microbes but still safe to consume because it is rid of pathogens
Why is it hard to sterilize food products
Because it can alter the flavor, color and nutritional value of food
What is decontamination and give an example
- mechanical removal of microbes
- ex: wiping up a bacterial spill with paper towels
- will never remove all of the microbes
T/F there is a set level to achieve with decontamination
False, not specific set level, it is very subjective. What is decontaminated to you may not be to me
What is Sanitization and give an example
Removal of microbes until it meets a specific health standard specified
-Mechanical and Chemical process
EX: cleaning silverware and glasses in food industry
What is preservation
the process of delaying spoilage of foods and other perishable products
-aimed at reducing or inhibiting the number of microbes
What are bacteriostatic preservatives
don’t kill the microbes, just slow their growth; can be any process that inhibits the growth of microbes
What are 5 different places microbial control would be needed
- daily life
- hospitals
- Microbiology labs
- Food production facilities
- Water treatment facilities
T/F there is always an ideal method for selection of effective control procedures
False
What are dependent factors when choosing a control method
- Type and number of microbes
- Environmental conditions
- Risk of infection
- Composition of infected item
What is the order (most to least) of resistance among different microbes
- prions
- endospores
- Acid Fast Bacteria (mycobacterium)
- Gram Negative Bacteria
- Naked virus
- Gram positive Bacteria
- Envelope virus
Selection of an Antimicrobial procedure: Type of microorganism (3 considerations)
- Is it a bacterial endospore, bacteria or virus
- Protozoan cysts and oocysts are resistant to disinfectants (excreted in feces)
- Pseudomonas species are resistant and can actually grow in some disinfectants
T/F all microbes are killed at once in any method
False, linear decrease, and mixed populations of different microbes with different susceptibilities will take various amounts of time based on what phase they are within their life cycle
What is the D-value
Decimal reduction time, the time it takes to kill 90% of population under specific conditions
-gauges commercial effectiveness
T/F it takes a larger population more time to die
True
T/F Removing organisms by washing increases time
False, decreases time
What are three environmental conditions to take into consideration
- organic matter
- pH
- Temperature
Consideration of organic matter
Dirt, grease, body fluids will interfere with heat penetration, action of chemicals. The disinfectant will be taken away by the interaction with the organic matter and will not be used to kill the microbes
Consideration of pH
lower pH is more effective
Consideration of Temperature
temperature will affect the enzymatic reactions within these microbes and are slightly enhanced by higher temperatures
What are the three levels to consider for risk of infection
- Critical items
- Semicritical instruments
- non-critical instruments
Critical items
- come in contact with body tissues
- must be sterile
- includes needles and scalpels
Semicritical instruments
- comes in contact with mucous membranes but does not penetrate body tissues
- can be disinfected, not sterilized
- Must be free of viruses and vegetative bacteria
- includes endoscopes and endotracheal tubes
non-critical instruments
- Contact unbroken skin only
- Low risk of transmission
- sanitized or decontaminated, sometimes may be disinfected
- countertops, stethoscopes, blood pressure cuffs
T/F Heat is appropriate for plastics and other sensitive items
False
T/F Irradiation can be an alternative for heat
Sometimes true, may still damage some types of plastic
When can moist heat and liquid chemical disinfectants not be used
to treat moisture-sensitive material
