Alcamo's ch 7
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What term is used to describe a process of destroying all living microbes, spores and viruses?
What does sanitation do?
Reduces # or pathogens or discourages their growth
The time necessary for killing the population at a given temp is known as the ___ ___ ___.
Thermal death time
When using a dry heat oven a temp of ___ for a period of ___ is required to kill bacterial spores.
How does dry heat kill microorganisms?
Changing microbial proteins by oxidation reactions creating an arid internal environment
How does moist heat kill microorganisms?
By denaturing proteins
A change in the physical or chemical properties of a protein is known as ___.
What is the most dependable method for sterilization including destroying bacterial spores?
Pressurized steam in an autoclave
In autoclaving the sterilizing agent is ___ ___ NOT ___.
Why is moist heat better than dry heat for sterilization?
It penetrates materials more rapidly b/c water conducts heat better than air
What is the std temp, psi & time for autoclaving?
121.5oC @ 15psi for 15 mins
Liquids and other objects exposed to 100oC for 30 mins w/an overnight incubation period at rm temp were sterilized with a process called what?
What are 4 methods of utilizing moist heat?
- Fractional sterilization
- Boiling (unreliable tho)
____ reduces the bacterial population of a liquid and destroys organisms that may cause spoilage and human disease.
T or F Spores are not effected by pasteurization.
The holding method of pasteurization involves heating at what temp for how long?
63oC for 30 mins
What 4 bacteria is pasteurization aimed at?
- M. tuberculosis
- C. Burnetii
- e. Coli
Flash pasteurization is accomplished at what temp for how long?
71.6oC for 15 sec
Ultra high temp pasteurization method is accomplished at what temp for how long?
140oC for 3 sec
What are 3 types of pasteurization?
- Holding or batch method
- Flash pasteurization method
- Ultra high temp method
___ is a mechanical method that can be used to remove microorganisms fr solution or gas.
Which type of filtration consists of a pad of cellulose acetate or polycarbonate mounted in a holding device?
What are membrane filters often used to purify?
- Heat sensitive liquids
- Bacteriological media
- Many pharmaceuticals
- Blood solutions
What does HEPA stand for and how does it work?
- High efficiency particulate air
- A mat of randomly arranged fibers that trap particles, microorganisms & spores
How does UV light control or kill microorganisms?
Cellular DNA absorbs light & adjacent thymine molecules link together kinking the double helix & disrupting DNA replication
How does ionizing radiation kill microorganisms?
By forcing electrons out of their shells creating ions which quickly combine w/cellular water and free radicals created affect cell metabolism & physiology
How does osmosis kill microorganisms?
By leaving them dehydrated and they die
Process used to destroy pathogenic organisms on or in an object or area is known as what?
A disinfectant is used on what?
Lifeless objects such as a tabletop
What is an antiseptic used on?
Something living such as tissue
What word refers to a condition in which microbes or their toxins are present in tissues or the blood?
A "microbial infection of the blood" is called ___.
The term asepsis means what?
Free of disease causing microbes
To ___ an object is to reduce the microbial population to a safe level as determined by public health standards.
Able to kill or slow growth of microorganisms
Nontoxic to animals or humans
Soluble in water
Substantial shelf life
Useful in diluted form
These are all characteristics of what?
Useful antiseptics or disinfectants
What chemical parameters should be considered when selecting an antiseptic or disinfectant?
- Temp at which it is most effective
- What pH it is effective
- Stability or how rapid the chem reaction is
- Type of microorganism to be eliminated
- Surface treated
Disinfectants are regulated by the ___ while antiseptics are regulated by the ___.
Iodine controls microorganisms by what means?
Reacting with proteins
What 3 mechanisms does alcohol use to kill microorganisms?
- Denatures proteins
- Dissolves lipids
- Dehydrating agent
What mechanisms of action does peroxide use (2)?
- Creates aerobic environment
- Oxidizes proteins
How does ethylene oxide kill microorganisms?
It reacts with functional grps in proteins & nucleic acids
What do surfactants do?
Emulsify & solubilize particles clinging to a surface & reduce surface tension
___ are synthetic chemicals acting as strong surfactants.
What is triclosan?
A bisphenol, broadspectrum antimicrobial that disrupts cell membranes by blocking synthesis of lipids
What is a neg side to triclosan use?
- Bacteria develop a resistance to it
- Can be cancer causing agent
How do heavy metals kill microorganisms?
By binding protein molecules together disrupting cellular metabolism
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