Microbiology Exam 2
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Microbiology Exam 2
Chapters 8 & 9
The complete elimination of all lifeforms, including endospores.
Does sterilization include endospores?
The elimination of all vegetative cells of pathogens.
Are all cells killed during disinfection? If not, what is left?
No, non-pathogenic cells may be present.
The reduction of pathogens to a "safe" level.
Sterilization uses what? Disinfection uses what? Sanitization uses what?
Disinfectants that have been approved for use on the body.
The specific way the method accomplishes killing or inhibition.
Mechanism of Action
What are the three most common mechanisms of action?
Damage to proteins and DNA
Altering of membrane permeability
Slowing down metabolism
What methods work by damaging proteins and DNA?
Wet Heat (denatures proteins)
Heavy Metals (interfere with protein function)
Radiation (damages DNA)
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
What mechanisms of action work by altering the permeability of cell membranes? How do they work?
Quarternary Ammonium Compounds
They insert themselves into the cell membrane and cause holes
What mechanisms of action work to slow down metabolism?
Cold and Dessication are what kind of methods?
The difference in Bacteriostatic and Bacteriocidal?
: slow down metabolism and stop reproduction of bacteria
: kill bacteria
Methods of Control can be what?
Physical or Chemical
How do Physical methods of control work?
Alter the physical environment.
What are some examples of Physical methods of control?
What are some Chemical methods of control?
Quaternary Ammonium Compounds
What mechanism of action is used by Moist Heat?
What is an example of Moist Heat?
Hot Water or Steam
What are some ways to use Moist Heat?
Boiling, Autoclaving, or Pasteurization
Do endospores survive boiling? Definitely under what time?
Usually yes, especially if boiling for under ten minutes
How do Autoclaves work?
They use steam under pressure.
What is the most common temperature and time used in Autoclaving?
121 degrees Celsius for 15 minutes (or 15psi).
What is the target organism for the pasteurization of milk?
What does Coxiella burnetti cause?
What are commercial canners called? What is their process called?
Retorts, commercial sterilization
What is the target organism for commercial canning?
Endospores of Clostridium botulinum
What is the most common case of botulism caused from?
Inadequately processed home canned foods.
What time and temperature should home canners be used at?
121 degrees Celsius for 15 minutes (or 15psi)
What is the mechanism of action for Dry Heat?
Kills by burning.
What is an example of Dry Heat?
Fire or Hot Air
What is a way to use Dry Heat?
Is Dry Heat more or less effective than Moist Heat at the same temperature?
What is the most common time and temperature used to sterilize with hot air?
160 degrees Celsius for 120 minutes
What objects are Dry Heat usually used on?
Glass or Metal, due to high temperatures
What happens to carcasses of cattle infected with anthrax?
They are often incinerated to make sure the endospores are destroyed.
What is anthrax caused by?
Flaming the loops in lab is an example of what method?
What is the mechanism of action for Cold?
What is a way we use Cold?
Freezing or Refrigeration
Cold temperatures are bacterio-static/cidal?
What is the growth of mesophiles inhibited by? What is the exception?
Refrigeration temperatures. Listeria monocytogenes.
Where do psychrotrophs grow? What are they responsible for?
Refrigeration temperatures. Refrigerated food spoilage.
What is the most common spoiler of raw meats?
What is the mechanism of action for Radiation?
What is an example of Radiation?
Ionizing and Non-Ionizing
What rays are ionizing?
What rays are Non-Ionizing?
Ionizing Radiation is energetic enough to do what?
Knock electrons off of atoms.
What are Gamma-Rays and X-Rays used for?
Sterilizing goods after packaging.
What is the most commonly used source of Gamma Rays?
What is UV Radiation useful for?
Surface and Air Treatment
Hospitals may have what kind of rays?
UV, to disinfect the air
What is the most effective wavelength of light? Why?
260 nanometers, DNA absorbs UV Rays best at that wavelength
UV light causes what?
The biological hood in the lab contains what type of Radiation?
What is the mechanism of action for Dessication?
What is something Dessication does?
Drying or Dehydrating Food
Is Dessication Bacterio-static/cidal?
Why does Dessication work?
All organisms require water, when moisture becomes too low enzymes no longer function
Foods with less than what percent of water content inhibit all bacterial growth?
Do Fungi or Bacteria tolerate low water levels best?
Where would molds more likely grow than bacteria?
Cheese and Bread
What is the mechanism of action for Osmotic Pressure?
Draws water out of cells and causes plasmolysis
What is something that causes Osmotic Pressure?
High levels of salt or sugar in moist foods
What are some foods where Osmotic Pressure is common?
Jellies, Jams, Honey, Syrup, Salted Meat
What pathogen may salty foods still be vulnerable to?
Staphylococcus aureus grows in water salt concentration?
More than 7%
What is the mechanism of action for filtration?
Where is filtration used?
Operating Rooms, Safety Hoods, Membrane Filters
What filters are used to filter air?
HEPA (high-efficiency particulate air filters)
HEPA filters capture a minimum of what percent and size of particles that pass through the filter?
99.97% of 0.3micrometers
Most bacteria are what size?
More than 1 micrometer
What are membrane filters used for?
To filter fluid.
What is the common size of a membrane filter pore?
What is the mechanism of action of Soaps and Detergents?
Decrease surface tension.
What does increased surface tension allow for bacteria?
To be lifted and carried off.
How much germicidal action do Soaps and Detergents have?
Little or No action.
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
To be able to put "antimicrobial" on a level, one must first do what?
Make sure the product meets government regulations.
Antimicrobial products are regulated by who?
FDA (Food and Drug Administration)
The EPA calls Antimicrobials what? The FDA calls them what?
What microbes are most resistant to chemicals?
Endospores and Mycobacteria
Why are endospores and mycobacteria most resistant to chemicals?
Their waxy mycolic acid coat.
Eukaryotic organisms are generally more/less resistant to chemicals?
Bacteria are most resistant to chemicals than what?
Among gram-negative bacteria, what species is particularly resistant to chemicals? Why?
Psuedomonas, their porins are more selective about what they let through
List major groups of microorganisms from MOST resistant to LEAST resistant to chemicals.
Cysts of Protozoa
Fungi (including spores)
What are most viruses surrounded by?
A membrane called an envelope.
What is the mechanism of action for Phenolics?
Disrupt cell membranes.
What is an example of a Phenolic?
What are Phenolics effective against?
What is Thymol an active ingredient in?
What is Triclosan an active ingredent in?
"Antibacterial" liquid handsoaps and detergents.
What is the mechanism of action of Halogens?
What are some examples of Halogens?
Fluoride, Chlorine, Hypochlorite (HOCl), Iodine, Iodophors
What is Fluoride used in?
What is Chlorine used for?
To treat drinking water.
What is Hypochlorite an active ingredient in?
What is Iodine used for?
Prepping the skin before an injection.
What are Iodophors?
Iodine combined with detergent.
What are Iodophors used for?
Prepping areas before surgery.
What is Alcohol's mechanism of action?
Inhibit proteins, dissolve lipids
What is an example of Alcohol?
What is Isopropanol useful for?
What is Ethanol often used for? Where do we also use it?
Injection prep, lab to soak metal spatulas
What is the most effective concentration of Ethanol or Isopropanol? Why?
70%, some water is needed to denature the proteins
What is the mechanism of actin for Heavy Metals?
What is an example of a Heavy Metal?
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
What is used for newborns today? To prevent what?
The antibiotic erythromycin, Chlamydia trachomatis eye infections
What has copper sulfate been used for?
Treat swimming pools and prevent algal growth, and on grapes to prevent fungal growth
What is the mechanism of action for Aldehydes?
What is an example of an Aldehyde?
Aldehyde is a potential what? Why?
Sterilant because it is effective against endospores, Carcinogen
What is the most effective group of disinfectants? Why aren't they used often?
Aldehydes, suspected carcinogens
Embalming solutions contain how much formaldehyde?
Quarternary Ammonium Compounds have what mechanism of action?
Disrupt cell membranes.
What is an example of a quat?
What is benzalkonium chloride usually listed as on labels?
Alkyl Dimethyl Benzyl Ammonium Chloride
Are Quats toxic/non-toxic? This allows them to be used where?
Non-toxic, sensitive areas like eyewash solutions
Quats are active ingredients in what?
Lysol, Fantastik, household sanitizers
Peroxides use what mechanism of action?
Cause various oxidation reactions
What is an example of a Peroxide?
H2O2, benzoyl peroxide
What peroxide is a household disinfectant?
What peroxide is common in topical acne medication?
What are the chromosomes of bacteria like?