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57 Cards in this Set
- Front
- Back
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Why do we bother with controlling microbial growth in the environment? |
-humans and microbes share the same environment -we are CONSTANTLY interacting w/ microbes -person-to-person -food and drinking water -medical devices |
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What is disinfection? |
reduction in the number of microbes on NON-LIVING OBJECTS/SURFACES
ex: iodine, alcohol, phenol, aldehydes, bleach, quaternary ammonium, metals |
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What is antisepsis? |
reduction in the number of microbes on LIVING TISSUE
ex: diluted disinfectants, iodine or alcohol |
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What is sanitization? |
reduction of microbes from objects/surfaces to meet a PUBLIC HEALTH STANDARD |
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What is sterilization? |
removal of ALL microbes from an OBJECT/SURFACE OR TISSUE |
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What does the term aseptic refer to? |
an environment or procedure free of pathogens |
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What do the suffixes "-cide" and "-cidal" refer to? |
destruction of a microbe |
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What do the suffixes "-stasis" and "static" refer to? |
inhibition of a microbe |
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How do we control microbiological growth? |
1. Temperature 2. Desiccation 3. Oxygen 4. Radiation 5. Acidity 6. Chemicals 7. Physical |
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How is microbiological growth controlled by lower temperatures? |
-refrigeration -freezing
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How is microbiological growth controlled by higher temperatures? |
-cooking -pasteurization -autoclaving -incineration -baking |
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What does heat do to a protein's structure? |
Damages (denatures it) -disrupts membranes/viral envelope -melts DNA to single strands |
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Describe how, when, and where dry heat is used to control microbiological growth. |
Hot air is used in baking. -Requires high temperatures for long periods of time -160 degrees Celsius for 2 hours -used on powders and oils |
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What is incineration? |
direction exposure to a flame or heating coils (form of dry heat) -1500 degrees Celsius -Time varies depending on volume |
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Moist heat is more _______ than dry heat. |
effective |
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Why is moist heat more effective than dry heat? |
Water is a better conductor of heat than air.
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What temperature does water boil at in Celsius? |
100 degrees Celsius |
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How fast are microbes in boiling water killed at sea level? |
Within 10 minutes |
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What is autoclaving? |
uses steam under pressure (example of moist heat) -121 degrees Celsius for 10 minutes will kill all microbes in a small volume -laboratory and medical settings |
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Where is pasteurization primarily used? |
in the food industry (milk) -63 degrees Celsius for 30 minutes -72 degrees Celsius for 15 seconds *does not kill heat tolerant microbes |
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What is ultrahigh-temperature sterilization? |
135 degrees Celsius for 1 second -affects taste |
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What is thermal death point? |
lowest temperature that kills all microorganisms in a liquid in 10 minutes |
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What is thermal death time? |
time to sterilize a volume of liquid at set temperature |
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What does refrigeration (0-7 degrees Celsius) do to microbial growth? |
-slows growth/metabolism -membranes shatter -makes proteins inflexible causing them to denature |
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What does freezing (below 0 degrees Celsius) do to microbial growth? |
-halts growth/metabolism -liquid water is unavailable -ice crystals puncture cells |
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What happens during desicacation? |
Proteins can't function without water (bad) Chromosomes fragments (lethal) |
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Desiccation is the principle behind? |
Jellies (sugar), brine (salt), and curing (salt) |
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What kinds of concentrations act just like desiccation? |
high salt or sugar concentrations (hypertonic solutions) |
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What are examples of oxygen that controls microbial growth? |
-hydrogen peroxide -bleach -ozone
all generate oxygen radicals |
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What happens when oxygen damage occurs? |
oxygen radicals react with and damage any macromolecule they come into contact with |
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What is superoxides most common target?
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DNA |
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What does superoxide do to chromosomes? |
cuts them apart |
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How does radiation control microbial growth? |
-ultraviolet lights causes mutation -ionizing radiation (x-rays, gamma rays) creates water radicals (h2oo]--> OH-) -OH- rips protons (H+) from DNA to return itself to H2o -This destroys the DNA |
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What is associated with irradiation of food? |
-gamma rays -create water radicals as they pass through microbes -destroys their DNA |
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Does irradiation of food make the food radioactive? |
NO. The internet is wrong. |
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Don't believe the internet because.... |
gamma rays are emitted by certain elements (ex. Cobalt-60) -cobalt-60 is a solid metal |
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What is the result of cobalt 60 radiating through an apple? |
PICKED APPLE: (still dead) DNA destroyed MICROORGANISMS (dead) DNA destroyed WATER=H20
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Deinococcus radiodurans is extremely ___________ resistant. |
radiation *5,000,000 rad vs 100 rad in humans
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Radiation creates water radicals that break the ___________of deinococcus radiodurans into pieces. |
chromosome |
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But the multiple chromosomes provide many copes to correctly__________. |
reassemble |
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How does acidity control microbial growth? |
dramatic changes in pH denatures proteins
Pickling (not just salt) |
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examples of acidophiles (thrive under acidic conditions) |
-stomach acid -lemon juice -vinegar -bread |
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What is a neutrophile? |
organism that thrives in neutral pH environments |
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Examples of alkalophiles (able to grow in alkaline concentrations as greater than 8.5) |
-soap -ammonia -drain cleaner |
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Examples of protein denaturants (chemicals) that control microbial growth. |
-alcohols (ethanon, isopropanol, halogens (iodine) |
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Examples of poisons (chemicals) that control microbial growth. |
-heavy metals (silver, mercury, arsenic) |
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Examples of membrane disruptors (chemicals) that control microbial growth. |
-phenolics (Lysol) -detergents |
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How do antibiotics (chemicals) control microbial growth? |
specifically target structures or reactions required for bacterial but not human growth |
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Why isn't soap included in the list of chemicals that control microbial growth? |
soap is not an antiseptic or disinfectant -one part of a soap molecule is hydrophobic and the other part is hydophilic (amphipathic) |
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What is filtration? |
Passage of air or liquid through a material that traps and removes microbes |
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What are 3 methods of air filtration? |
1. Surgical masks 2. Biosafety Cabinets 3. HEPA filters (High Efficiency Particulate Air) |
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Pore size determines which microbes are trapped. |
The smaller the pore size the smaller the microbe can be. The bigger the pore size the bigger the microbe. |
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When selecting antimicrobials, remember to consider what two things? |
1. The nature of the site to be treated 2. Level of microbial control |
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When considering the nature of the site to be treated, it is important to know that harsh chemicals and extreme heat cannot be used on ________, __________, or ___________ __________. |
humans, animals, fragile objects (plastics) |
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When considering the level of microbial control, it is important to know that breaching the body's defenses requires _________ _______________. |
sterile instruments |
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Interacting with the mucous membranes or skin only requires _______________ of instruments. |
disinfection -unless the patient is immunocompromised |
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When selecting antimicrobials remember to consider.... |
-degree of susceptibility of microbes involved -usually a function of cell walls, membranes/envelopes, resting structures |
