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38 Cards in this Set
- Front
- Back
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sepsis
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microbial contamination
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asepsis
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absence of significant contamination
-aseptic surgery techniques prevent microbial contamination of wounds |
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Sterilization
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removal of all microbial life
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commercial sterilization
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killing C.botulinum endospores
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disinfection
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removal of pathogens
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antisepsis
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removal of pathogens from living tissue
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degerming
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removal of microbes from a limited area
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sanitization
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lower microbial counts on eating utensils
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biocide/germicide
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kills microbes
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bacteriostasis
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inhibiting, not killing, microbes
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Effectiveness of antimicrobial treatment depends on
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-number of microbes
-environment (organic matter, temperature, biofilms) -time of exposure -microbial characteristics |
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Actions of microbial control agents
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-Alternation of membrane permeability
-Damage to proteins -Damage to nucleic acids |
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Physical methods of microbial control
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heat
filtration low temperature high pressure desiccation osmotic pressure radiation |
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thermal death point (TDP)
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lowest temperature which all cells in a culture are killed in 10 min
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thermal death time (TDT)
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time to kill all cells in a culture
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decimal reduction time (DRT)
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minutes to kill 90% of a population at a given temperature
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Moist heat
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denatures proteins
Autoclave, Pasteurization |
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Autoclave
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steam under pressure
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Pasteurization
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reduces spoilage organisms and pathogens. Thermoduric organisms survive.
Standard: 63C for 30 min High temp, short time: 72C for 15 sec Ultra-high-temp: 140C for <1 sec |
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Dry Heat
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Sterilization kills by oxidation
Flaming, Incineration, Hot-air sterilization Hot-air 170C, 2 hours = Autoclave 121C, 15 min. |
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filtration
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removes microbes
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low temperature
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inhibits microbial growth
-refridgeration, deep freezing, lyophilization |
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high pressure
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denatures proteins
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desiccation
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prevents metabolism
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osmotic pressure
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causes plasmolysis
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radiation
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damages DNA
-Ionizing radiation (Xrays, gamma rays, electron beams) -Nonionizing radiation (UV) (microwaves kill by heat, not especially antimicrobial) |
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principles of effective disinfection
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concentration of disinfectant
organic matter pH Time |
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Evaluating a disinfectant
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Use-dilution test
Disk-diffusion method |
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Use-dilution test
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1. Metal rings dipped in test bacteria are dried
2. Dried cultures placed in disinfectant for 10 min at 20 degrees C 3. Rings transferred to culture media to determine whether bacteria survived treatment |
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Disrupt plasma membranes
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phenol, phenolics (lysol), bisphenols (hexachlorophene, triclosan), biguanides (chlorhexidine)
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oxidizing agents
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halogens (iodine, chlorine)
Antiseptics: Iodine Chloramines Disinfectants: Bleach is sodium hypochlorite (NaOCl); ClO2; chloramines |
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denature proteins, dissolve lipids
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alcohols (ethanol, isopropanol)
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denature proteins
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heavy metals (Ag, Hg, Cu) -- ologodynamic action denature proteins
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surface-active agents or surfactants
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soap: degerming
acid-anionic detergents: sanitizing Quarternary ammonium compounds (cationic detergents): germicidal, denature proteins, disrupt plasma membrane |
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chemical food preservatives
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organic acids- control molds and bacteria in foods and cosmetics by inhibiting metabolism
nitrite- prevents endospore germination antibiotics- nisin and natamycin prevent spoilage of cheese |
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aldehydes
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Inactive proteins by cross-linking with functional groups
eg Glutaraldehyde (disinfect/sterilize hospital equipment); Formaldehyde (formalin) |
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Gaseous Sterilants
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denature proteins
eg Ethylene oxide |
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peroxygens
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oxidizing agents
eg O3, H2O2, peracetic acid |
