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56 Cards in this Set
- Front
- Back
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Antisepsis |
-used living tissue -or on inert substance -Reduction in the number of microorganisms and viruses, particularly potential pathogens, on living tissue |
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Aseptic |
Refers to an environment or procedure free of pathogenic contaminants |
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-cide -cidal |
a chemical that kills -suffixes indicating destruction of a type of microbe " virocide, fungicide" |
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Degerming |
removal of microbes by mechanical means
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Disinfection
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-tion: not
destruction of most microorganisms and viruses on nonliving tissue -safe enough for living tissue |
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Pasteurization |
Use of heat to destroy pathogens and reduce the number of spoilage microorganisms in foods and beverages
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Sanitization
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"restaurants" remove enough for safety
Removal of pathogens from objects to meet public health standards |
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-stasis
-static |
bacteriostatic agent, does not kill; it prevents growth.
suffixes indicating inhibition, but not complete destruction, of a type of microbe. |
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Sterilization
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killing ALL microbes off.
Destruction of all microorganisms and viruses in or on an object. |
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Factors affecting how long it takes to kill bacteria...
N E T - C |
Number of microbes Environment Time of exposure Characteristics of microbes |
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Environment : |
slowed by organic materials, biofilms (e.g., feces, sewage) hastened by prior cleaning, heat |
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Characteristics of microbes: most resistant are.... |
spores (ex: Clostridium difficile) thick lipid coats protozoan cysts |
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Microbial Sensitivity to Chemical Biocides |
most RESISTANT prions bacterial endospores mycobacteria cysts of protozoa active-stage protozoa (trophozoites) most gram-negative bacteria fungi nonenveloped viruses most gram-positive bacteria enveloped viruses most SUSCEPTIBLE |
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Actions: Alteration of membrane permeability |
poking holes in the membrane= spilling guts -outsides go in; insides go out |
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Damage to proteins and nucleic acids |
-if the proteins are damaged, they will most likely not work anymore
-some more critical than others -cannot do work |
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Mutation |
-non-funcational proteins
-screws up DNA |
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Physical Control Methods T - D O R |
Temperature Desiccation; drying out Osmotic pressure Radiation |
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Types of Temperature methods.... |
Heat preservation; pasteurization
Moist heat Dry heat Low heat |
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Heat Preservation |
-Must know temp. and time needed to kill critical bacteria
-Thermal death time -how long it takes to kill a certain bacteria at a certain temp |
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Pasteurization |
Used when taste of product would be damaged by longer heating
-lowers numbers of pathogens (63*C for 30 minutes) typically pasteurized: milk, juice, yogurt and ice cream -UHT: sterilization (140*C for 1-3 seconds) --- product may lose some nutritional value |
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Moist Heat |
Coagulates proteins by breaking hydrogen bonds (denatures) -Boiling -- 10 mins kills most pathogens --Hepatitis virus nbeeds 30 minutes -- spores need 20 hours! Autoclave: 15 psi for 15 minutes at 121*C |
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Autoclave |
-uses pressure and MOIST heat to kill microbes
-similar to rice cooker procedure -sterilizes |
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Dry Heat
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-flaming
-oven (170*C 2 hours) -spores are resistant to dry heat!!!! |
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Low Temperature
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-can preserve organisms
-refrigeration is bacteriostatic (does not kill; prevents growth) ---most pathogens do not grow ---Listeria spp. are psycrotolerant -------Freezing: ---slow freezing creates ice crystals * that can sheer cell membranes causing cell death when they thaw*** ---ice in the membrane can shatter it (95% ethynol and dry ice- freezing pathogens) |
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Membrane Filtration |
-Pore SIZE controls which microbes are removed --filter sterilization with 0.2 micrometers -HEPA filters used in safety hoods and operating theaters |
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Limiting Water |
Desiccation: bacteriostatic (does not kill pathogens; prevents growth)
--Lyophilization: used to preserve cultures** used as freeze drying to preserve organisms** -Osmotic pressure- high concentrations of salt and sugar -Molds and yeasts most resistant |
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Radiation:** WONDERFUL WAY of killing ** Ionizing Radiation... |
gamma rays, X rays, high energy electron beams - most energetic
- ionization of H2O to form OH- radicals -Cause mutations in DNA and death |
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Low level ionizing radiation.... |
-used on spices, certain meats and vegetables
-high energy electron beams used for medical supplies |
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UV Radiation |
-Thymine dimers in DNA
-Germicidal lamps, vaccine disinfection -Not penetrating -Can damage eyes **** UV Radiation; T's will bind to themselves instead of A's; during replication this causes mistakes.**** |
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Microwaves |
-very little effect on some microbes
-microwave oven kill vegetative pathogens by heating -solid foods heat unevenly **** place a bowl of H2O in microwave-steam destroys microbes*** |
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Chemical Methods
DS CAGO[A] "Chicago" |
-Disinfectants/antiseptics -Surface-active agents (surfactants) -Chemical food preservatives -Aldehydes (formaldehyde = formalin) -Gas sterilization -Oxidizing agents -Antibiotics |
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Disinfectants/antiseptics |
-Phenols --damage lipid membranes --active in presence of organic matter --sable --persist for long periods after application --example - Dettol |
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Phenols.... |
originally used by Joseph Lister, as carbolic acid vapors during surgery ** some phenols can be used as antiseptics**** |
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Disinfectants/antiseptics |
-Bisphenols -Hexachlopophene (pHisoHex) and triclosan (mouthwash) -Antibacterial soaps and toothpaste -Broad spectrum of activity |
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Disinfectants/antiseptics
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-Biguanides
--Chlorhexidine (wonderful antiseptic) --low toxicity --used on skin and mucous membranes --surgical scrub in veterinary hospitals |
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Disinfectants/ antiseptics |
-Halogens*** used a lot, and wonderful to clean wounds, cuts-does not burn used with...
--Iodine ---used in solution ---Betadine and Isodine -Chlorine ---gas that forms bleach (hypochlorite) in water ---destroys cell walls and enzymes (coagulates proteins and enzymes) |
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Disinfectants/antiseptics |
-Alcohol
--protein denaturation and membrane damage -evaporate quickly ---good and bad **90 seconds to really kill all microbes** one alcohol swipe before a prick won't kill off much from skin*** -Ethanol and isopropanol most common -100% alcohol is not good as denaturing proteins requires water molecules |
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Evaluation of Disinfectants/antiseptics |
IN THE AGAR: -closer to disk= higher concentration of chemical -one chemical is not sufficient for everything |
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Heavy Metals as Disinfectants
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-denature proteins
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Silver Nitrate |
(topical cream) |
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Mercuric Chloride (paint) |
- **red paint on wounds; pretty toxic--- used to be used as an antiseptic---poisonous---was used to treat syphilis |
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Copper Sulfate |
algicide ** burn creams** |
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Zinc ( mouthwash, paints) |
antibacterial effects
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Surfactants
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Decrease surface tension damage lipid membranes ** attracted to membranes-- distrupts them. Insert themselves inside but not evenly.
** soaps and detergents ---quaternary ammonium compounds: microbial
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Quaternary Ammonium Compounds ( Quats) |
Ammonium ions
Benzalkonium chloride |
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Chemical Food Preservatives |
Sodium benzoate Sorbic acid Calcium propionate Sodium nitrate and sodium nitrite |
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Sodium benzoate |
In acidic foods
reduces pH to 5 or lower which inactivates phosphofructokinase |
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Sorbic acid |
weak acids
inhibit enzymes |
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Calcium propionate
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used in breads
non-toxic, but inhibits growth |
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Sodium nitrate and sodium nitrite
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Inhibits Clostridium botulinum
toxic |
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Aldehydes
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Formaldehyde (formalin) and glutaraldehyde
-used to disinfect instruments -used to preserve tissues for pathology -irreversibly cross-linked protein molecules |
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Gas Sterilization
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Put into a chamber where ethylene oxide is pumped inside to sterilize
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Ethylene oxide
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-denatures proteins
-kills all spores and microbes with lengthy exposure -high penetration -for use when sensitive to heat or moisture |
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Oxidizing Agents OH BP |
Ozone Hydrogen peroxide *really toxic;bubbling* Benzoyl peroxide Practice acid --interfere with metabolism (especially of anaerobes) |
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Antiseptic Effectiveness: Soap and Water |
does not kill bacteria! can have an affect with out killing microbes though...
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Chemical Effectiveness |
you must leave the chemical on for the appropriate time to be effective |
