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14 Cards in this Set
- Front
- Back
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Practical concerns in microbial control
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-nature of organism
-is sterilization required, or is disinfection adequate -is the item to be reused or discarded -can the item withstand heat, pressure, radiation, chemicals -is the method cost and labor efficient, and safe |
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Define microbial death
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when a cell can no longer reproduce under ideal environmental conditions
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Factors affecting microbial cell death rate
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bioburden - # of organisms
type of organism - spores vs cells environment - temp, ph, humidity concentration and MOA of agent presence of other substances - solvents, |
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Mechanism of Action of microbial agents
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-damage cell wall
-damage cell membrane -affect protein and nucleic acid synthesis -alter protein function |
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Elevated temperatures
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germicidal/microbicidal
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Lower temperatures (refrigeration)
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germistatic/microbistatic
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Moist Heat - MOA
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coagulates and denatures proteins, usually in the form of boiling water or steam
ex:autoclave |
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Dry Heat - MOA
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cells are oxidized and burned to ashes, >160 degrees C
ex: Flaming culture loops |
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Thermal death time (TDT)
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the shortest length of time required to kill all test microbes at a specified temperature
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Thermal death point (TDP)
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the lowest temperature required to kill all microbes in a sample in 10 minutes
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Effects of Cold Temperature
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slows growth of cultures and microbes, does not kill microbes, merely retards cellular activities
freezing can actually preserve cultures |
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Ionizing Radiation
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"cold" sterilization
uses: food products, medical supplies |
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Non-ionizing Radiation
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UV radiation
Disinfectant uses: hospital rooms, schools, food prep areas, treating drinking water |
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Filtration
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Decontamination, removes microbes from air and liquids
filters are used with variable pore sizes uses: water purification, removing airborne contaminants |
