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The complete elimination of all lifeforms, including endospores.
Sterilization
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Does sterilization include endospores?
Yes.
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The elimination of all vegetative cells of pathogens.
Disinfection
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Are all cells killed during disinfection? If not, what is left?
No, non-pathogenic cells may be present.
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The reduction of pathogens to a "safe" level.
Sanitization
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Sterilization uses what? Disinfection uses what? Sanitization uses what?
- Sterilants
- Disinfectants
- Sanitizers
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Disinfectants that have been approved for use on the body.
Antiseptics
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The specific way the method accomplishes killing or inhibition.
Mechanism of Action
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What are the three most common mechanisms of action?
- Damage to proteins and DNA
- Altering of membrane permeability
- Slowing down metabolism
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What methods work by damaging proteins and DNA?
- Wet Heat (denatures proteins)
- Heavy Metals (interfere with protein function)
- Radiation (damages DNA)
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Damage to cell membrane causes the membrane to become what? What could this lead to?
Leaky, loss of nutrients or permits entry of undesirable substances
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What mechanisms of action work by altering the permeability of cell membranes? How do they work?
- Phenolics
- Quarternary Ammonium Compounds
- They insert themselves into the cell membrane and cause holes
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What mechanisms of action work to slow down metabolism?
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Cold and Dessication are what kind of methods?
Bacteriostatic
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The difference in Bacteriostatic and Bacteriocidal?
- Bacteriostatic: slow down metabolism and stop reproduction of bacteria
- Bacteriocidal: kill bacteria
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Methods of Control can be what?
Physical or Chemical
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How do Physical methods of control work?
Alter the physical environment.
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What are some examples of Physical methods of control?
- Heat/Cold
- Radiation
- Desiccation/Osmotic Pressure
- Filtration
- Soaps/Detergents
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What are some Chemical methods of control?
- Phenolics
- Halogens
- Alcohols
- Heavy Metals
- Aldehydes
- Quaternary Ammonium Compounds
- Peroxides
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What mechanism of action is used by Moist Heat?
Denatures protein.
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What is an example of Moist Heat?
Hot Water or Steam
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What are some ways to use Moist Heat?
Boiling, Autoclaving, or Pasteurization
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Do endospores survive boiling? Definitely under what time?
Usually yes, especially if boiling for under ten minutes
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How do Autoclaves work?
They use steam under pressure.
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What is the most common temperature and time used in Autoclaving?
121 degrees Celsius for 15 minutes (or 15psi).
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What is the target organism for the pasteurization of milk?
Coxiella burnetii
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What does Coxiella burnetti cause?
Q Fever
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What are commercial canners called? What is their process called?
Retorts, commercial sterilization
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What is the target organism for commercial canning?
Endospores of Clostridium botulinum
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What is the most common case of botulism caused from?
Inadequately processed home canned foods.
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What time and temperature should home canners be used at?
121 degrees Celsius for 15 minutes (or 15psi)
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What is the mechanism of action for Dry Heat?
Kills by burning.
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What is an example of Dry Heat?
Fire or Hot Air
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What is a way to use Dry Heat?
Incineration
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Is Dry Heat more or less effective than Moist Heat at the same temperature?
Less effective.
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What is the most common time and temperature used to sterilize with hot air?
160 degrees Celsius for 120 minutes
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What objects are Dry Heat usually used on?
Glass or Metal, due to high temperatures
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What happens to carcasses of cattle infected with anthrax?
They are often incinerated to make sure the endospores are destroyed.
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What is anthrax caused by?
Bacillus anthracis
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Flaming the loops in lab is an example of what method?
Dry Heat
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What is the mechanism of action for Cold?
Slows metabolism.
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What is a way we use Cold?
Freezing or Refrigeration
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Cold temperatures are bacterio-static/cidal?
Bacteriostatic
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What is the growth of mesophiles inhibited by? What is the exception?
Refrigeration temperatures. Listeria monocytogenes.
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Where do psychrotrophs grow? What are they responsible for?
Refrigeration temperatures. Refrigerated food spoilage.
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What is the most common spoiler of raw meats?
Pseudomonas fragi
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What is the mechanism of action for Radiation?
Damages DNA
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What is an example of Radiation?
Ionizing and Non-Ionizing
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What rays are ionizing?
- Gamma Rays
- X-Rays
- Electron Beams
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What rays are Non-Ionizing?
UV
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Ionizing Radiation is energetic enough to do what?
Knock electrons off of atoms.
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What are Gamma-Rays and X-Rays used for?
Sterilizing goods after packaging.
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What is the most commonly used source of Gamma Rays?
Cobalt-60
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What is UV Radiation useful for?
Surface and Air Treatment
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Hospitals may have what kind of rays?
UV, to disinfect the air
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What is the most effective wavelength of light? Why?
260 nanometers, DNA absorbs UV Rays best at that wavelength
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UV light causes what?
Thymine Dimers
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The biological hood in the lab contains what type of Radiation?
UV Light
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What is the mechanism of action for Dessication?
Slows metabolism
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What is something Dessication does?
Drying or Dehydrating Food
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Is Dessication Bacterio-static/cidal?
Bacteriostatic
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Why does Dessication work?
All organisms require water, when moisture becomes too low enzymes no longer function
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Foods with less than what percent of water content inhibit all bacterial growth?
20%
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Do Fungi or Bacteria tolerate low water levels best?
Fungi
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Where would molds more likely grow than bacteria?
Cheese and Bread
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What is the mechanism of action for Osmotic Pressure?
Draws water out of cells and causes plasmolysis
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What is something that causes Osmotic Pressure?
High levels of salt or sugar in moist foods
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What are some foods where Osmotic Pressure is common?
Jellies, Jams, Honey, Syrup, Salted Meat
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What pathogen may salty foods still be vulnerable to?
Staphylococcus aureus
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Staphylococcus aureus grows in water salt concentration?
More than 7%
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What is the mechanism of action for filtration?
Removes microbes.
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Where is filtration used?
Operating Rooms, Safety Hoods, Membrane Filters
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What filters are used to filter air?
HEPA (high-efficiency particulate air filters)
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HEPA filters capture a minimum of what percent and size of particles that pass through the filter?
99.97% of 0.3micrometers
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Most bacteria are what size?
More than 1 micrometer
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What are membrane filters used for?
To filter fluid.
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What is the common size of a membrane filter pore?
0.45 micrometer
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What is the mechanism of action of Soaps and Detergents?
Decrease surface tension.
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What does increased surface tension allow for bacteria?
To be lifted and carried off.
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How much germicidal action do Soaps and Detergents have?
Little or No action.
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What do Soaps and Detergents do to microbes?
Rather than kill, they make it easier for rubbing and rinsing to carry away any microbes on a surface
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To be able to put "antimicrobial" on a level, one must first do what?
Make sure the product meets government regulations.
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Antimicrobial products are regulated by who?
FDA (Food and Drug Administration)
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The EPA calls Antimicrobials what? The FDA calls them what?
Pesticides, Drugs
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What microbes are most resistant to chemicals?
Endospores and Mycobacteria
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Why are endospores and mycobacteria most resistant to chemicals?
Their waxy mycolic acid coat.
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Eukaryotic organisms are generally more/less resistant to chemicals?
More
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Bacteria are most resistant to chemicals than what?
Viruses.
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Among gram-negative bacteria, what species is particularly resistant to chemicals? Why?
Psuedomonas, their porins are more selective about what they let through
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List major groups of microorganisms from MOST resistant to LEAST resistant to chemicals.
- Endospores
- Mycobacteria
- Cysts of Protozoa
- Vegetative Protozoa
- Gram-Negative Bateria
- Fungi (including spores)
- Non-Enveloped Viruses
- Gram-Positive Bacteria
- Enveloped Viruses
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What are most viruses surrounded by?
A membrane called an envelope.
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What is the mechanism of action for Phenolics?
Disrupt cell membranes.
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What is an example of a Phenolic?
Thymol, Triclosan
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What are Phenolics effective against?
Mycobacteria
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What is Thymol an active ingredient in?
Listerine
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What is Triclosan an active ingredent in?
"Antibacterial" liquid handsoaps and detergents.
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What is the mechanism of action of Halogens?
Inhibit proteins.
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What are some examples of Halogens?
Fluoride, Chlorine, Hypochlorite (HOCl), Iodine, Iodophors
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What is Fluoride used in?
Toothpaste (1000ppm)
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What is Chlorine used for?
To treat drinking water.
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What is Hypochlorite an active ingredient in?
Bleach (5%)
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What is Iodine used for?
Prepping the skin before an injection.
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What are Iodophors?
Iodine combined with detergent.
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What are Iodophors used for?
Prepping areas before surgery.
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What is Alcohol's mechanism of action?
Inhibit proteins, dissolve lipids
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What is an example of Alcohol?
Ethanol, Isopropanol
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What is Isopropanol useful for?
Household disinfectant.
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What is Ethanol often used for? Where do we also use it?
Injection prep, lab to soak metal spatulas
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What is the most effective concentration of Ethanol or Isopropanol? Why?
70%, some water is needed to denature the proteins
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What is the mechanism of actin for Heavy Metals?
Inhibit Proteins
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What is an example of a Heavy Metal?
Silver, Copper
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What was put onto the eyes of newborns? Why?
Drops of 1% Silver Nitrate, to prevent the organism Neisseria gonorroheae infections, passed from mother during birth
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What is used for newborns today? To prevent what?
The antibiotic erythromycin, Chlamydia trachomatis eye infections
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What has copper sulfate been used for?
Treat swimming pools and prevent algal growth, and on grapes to prevent fungal growth
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What is the mechanism of action for Aldehydes?
Inhibit Proteins.
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What is an example of an Aldehyde?
Formaldehyde.
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Aldehyde is a potential what? Why?
Sterilant because it is effective against endospores, Carcinogen
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What is the most effective group of disinfectants? Why aren't they used often?
Aldehydes, suspected carcinogens
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Embalming solutions contain how much formaldehyde?
15%
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Quarternary Ammonium Compounds have what mechanism of action?
Disrupt cell membranes.
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What is an example of a quat?
Benzalkonium chloride
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What is benzalkonium chloride usually listed as on labels?
Alkyl Dimethyl Benzyl Ammonium Chloride
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Are Quats toxic/non-toxic? This allows them to be used where?
Non-toxic, sensitive areas like eyewash solutions
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Quats are active ingredients in what?
Lysol, Fantastik, household sanitizers
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Peroxides use what mechanism of action?
Cause various oxidation reactions
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What is an example of a Peroxide?
H2O2, benzoyl peroxide
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What peroxide is a household disinfectant?
Hydrogren Peroxide
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What peroxide is common in topical acne medication?
Benzoyl Peroxide
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What are the chromosomes of bacteria like?
Singular, Circular
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