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55 Cards in this Set
- Front
- Back
sterilization:
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the destruction or removal of ALL microbes.
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*suffix*
-static |
an agent that inhibits growth, but does not kill.
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*suffix*
-cidal |
an agent that kills.
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aseptic:
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an environment or procedure free from contamination.
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disinfection:
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the use of chemical or physical agents to kill or inhibit the growth of microorganisms.
*does not always kill all microbes |
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disinfectant:
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a chemical that is used on an inanimate object.
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antiseptic:
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a chemical that is used on skin and tissue.
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What are some important things to note about disinfectants/antiseptics?
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some disinfectants are also antiseptics.
just don't want a chemical to kill tissue, so some can't be. |
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degerming:
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the removal of microbes from a surface by mechanical means.
Ex. alcohol swab before injections |
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sanitation:
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disinfection of places or things used by the public.
used to reduce # of pathogens. not the same thing as sterilization. |
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pasteurization:
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using heat to kill pathogens: used in the food industry.
does not completely sterilize |
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What are the targets of disinfectants and antiseptics?
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-plasma membrane
-proteins -cell wall -nucleic acids |
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surfactants:
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disrupt the plasma membrane.
made of polar molecules with hydrophobic and hydrophilic regions. |
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heat and strong solvents:
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break hydrogen bonds.
this denatures proteins. |
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metallic ions:
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inhibit enzymatic function by blocking the active site
Ex. silver ions |
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radiation:
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interferes with DNA and RNA function
causes mutations which can permanantly inactivate nucleic acids. |
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which factors affect the rate of microbial death?
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-number of microbes
-duration of exposure to agent -temperature -environment of the microbes -endospore formation |
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What is clinically relevant about the microbial environment?
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they are associated with organic material (gross) which inhibits access of the antimicrobial agent.
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What is important about endospore formation?
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*may be the most important factor affecting rate of microbial death
these organisms are NOT susceptible to most chemical agents. |
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What are the three major methods for controlling microbial growth?
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-chemical
-physical (heat/radiation) -mechanical (filtration/degerming) |
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increase in concentration =
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an increase in potency
except for alcohol. it needs to have some water in order to denature proteins. ex. 100% ethanol is LESS effective than 70% ethanol. |
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What are some ways of evaluating antimicrobial chemical agents?
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-phenol coefficient
-disk method -use dilution method |
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Who first used phenol as a disinfectant?
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Joseph Lister
-in 1867- |
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describe the phenol coefficient
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a way to compare disinfectants
1.0 = same effectiveness as phenol > 1.0 = greater efficiency < 1.0 = lesser efficiency |
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describe the disk method
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tiny disks of filter paper are soaked in the agent and placed on an inoculated agar plate. Inhibition of growth around the disk is called the zone of inhibition.
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What are some limitations of the disk method?
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-sizes of the zones are not comparable because they may reflect a difference in concentration and diffusion rate.
-cannot distinguish between microbicidal and microbistatic. |
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What should one consider when selecting an antimicrobial agent?
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-is it reactive against all organisms without destroying tissue?
-is it effective in the presence of organic material? -is it stable, and hopefully inexpensive? |
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Chemical agents are...
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used more frequently than physical means
ineffective against protozoan cysts and bacterial endospores. |
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What are eight major categories of chemical agents?
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-phenol and phenolic compounds
-alcohols -halogens -oxidizing agents -surfactants -heavy metals -aldehydes -gaseous agents |
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Phenol and phenolic compounds.
-use/properties?- |
-effective in presence of organic material
-commonly used as disinfectants in hospitals. |
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phenol and phenolic compounds
-examples?- |
-Lysol
-triclosan |
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alcohols
-use/properties?- |
-disinfectant AND antiseptic
-used as degerming agent before injections |
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alcohols
-examples?- |
-isopropanol (rubbing alcohol)
-ehanol |
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halogens
-use/properties?- |
some are disinfectants and some are antiseptics
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halogens
-examples?- |
-iodine- one of the oldest antiseptics
-tincture (iodine + alcohol) -iodophore (iodine + organic) it is slow releasing and less irritating. -chlorine- swimming pools/ bleach |
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oxidizing agents
-examples?- |
-hydrogen peroxide: household antiseptic (not very effective)
-ozone: hot tubs/ water supply |
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surfactants
-use/properties?- |
-soap: good degerming, but not so good antimicrobial
-detergent: may have antimicrobial, more soluble, no soap scum *soap makes water wetter* |
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surfactants
-examples?- |
-QUATS: quaternary ammonium compounds
pseudomonas can still grow in this! eek |
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heavy metals
-use/properties?- |
used to be used in eyes of newborns to prevent gonorrhea
still used in surgical dressings and burn creams bacteriostatic |
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heavy metals
-examples?- |
silver nitrate
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gaseous agents
-use/properties?- |
for things that are sensitive to heat or chemicals
explosive, poisonous |
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gaseous agents
-examples?- |
ethyline oxide
(dentists use it) |
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aldehydes
-use/properties?- |
disinfectants NOT antiseptics
innactivate proteins and nucleic acids irritate mucous membranes |
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aldehydes
-examples?- |
-formaldehyde: used to disinfect isolation rooms/surg. equipment /dialysis machine
-glutaraldehyde |
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What are the two ways to use heat for killing microbes?
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Dry heat: oven/flame/incinerator - for glass or powders
moist heat: more penetrating - boiling won't kill endospores |
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What are the three ways of using moist heat?
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-boiling
-pressurized steam (autoclave) kills endospores -paseurization |
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How does an autoclave work?
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pressurized steam: it can be heated higher than boiling water
don't put things that are sensitive to heat or moisture in autoclave. |
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How does an autoclave kill endospores?
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it heats up to 121 degrees and 15 pounds per square inch. endospores die within 15 minutes.
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What are some other methods of controlling microbial growth?
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-filtration
-radiation -non-ionizing radiation (UV light) |
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What is filtration used for?
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to sterilize air or liquids
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How is non-ionizing radiation used?
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germicidal lamps
surfaces only damages skin and eyes |
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Why is ionizing radiation safe?
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the radioactive substance does not actually touch the foods. they do not become radioactive. that's just silly.
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Why are antibiotics important?
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they have drastically reduced the number of deaths due to infection.
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How many antibiotic prescriptions are written in america each year?
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an estimated 80 million
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how much antibiotic is produced each year?
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12500 tons
with 25-50% being fed to livestock to increase weight gain. |