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Microbio > Disinfection & Sterilization > Flashcards

Disinfection & Sterilization Flashcards

1
Q

Compare and contrast sterilization with sanitization

A

Both are cleaning methods but sterilization involves the destruction of all living microbes, spores, and viruses, sanitation only reduces the number of pathogens/discourages growth

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2
Q

What are the physical methods of disinfection

A

heat
radiation
filtration

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3
Q

How does heat attack cells?

A

destroys proteins and nucleic acids
water is removed

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4
Q

the minimum temp at which all bacteria in a culture will die within 10 minutes

A

Thermal Death Point (TDP)

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5
Q

DRT-value (decimal reduction time) defines what?

A

defines heat resistant bacteria

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6
Q

requires LONG periods of exposure

A

Dry heat

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7
Q

faster and effective at low temperatures

A

Moist heat

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8
Q

how does moist heat disrupt cells?

A

denatures proteins and coagulates them

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9
Q

application of steam heat and pressure, kills vegetative cells, bacterial spores, fungi, and viruses in approx. 15 min

A

Autoclaving

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10
Q

Process of autoclaving

A

items placed in the chamber, air is evacuated by a vacuum pump, and steam is forced into the chamber at a high temperature

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11
Q

things that can be sterilized by autoclaving

A

medical waste
infectious materials
culture media
surgical tools
lab glassware

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12
Q

reduces the chances of spoilage and disease in milk

A

Pasteurization

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13
Q

what is not affected by pasteurization?

A

bacterial SPORES

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14
Q

traps microorganisms

A

Filtration

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15
Q

why is filtration useful?

A

it is useful for sterilizing liquids that can be destroyed by heat

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16
Q

how does filtration work?

A

organisms above a certain size threshold are trapped in the pores of the filter

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17
Q

types of radiation

A

UV
Ionizing

18
Q

Crosslinks nucleic acids rendering organism unable to replicate genetic material

A

UV Radiation

19
Q

X-ray, Gamma-ray, or microwave radiation create strand breaks in in nucleic acids rendering organism unable to replicate genetic material

A

Ionizing radiation

20
Q

pros and cons of radiation

A

active against spores but they can have resistance to low level radiation

21
Q

Physical methods of food preservation

A

Drying (removes water)
Salting/curing (removes water through osmosis)
Low temps (lower microbial growth rates)

22
Q

chemical agent the is used to kill microbes on living tissue

A

Antiseptics

23
Q

chemical agents that is used to kill microbes on a non-living surface

A

Disinfectants

24
Q

High-level disinfectants

A

Hydrogen peroxide
Chlorine
Chlorine dioxide
Gas vapor

25
Q

Mid-level disinfectants

A

Alcohol
Iodine

26
Q

Low-level disinfectants

A

Quartenary Ammonium compounds
Soap and Hot Water

27
Q

How does hydrogen peroxide destroy cells?

A

destroys proteins and membranes

28
Q

How does chlorine destroy cells?

A

highly reactive oxidizer
destroys proteins, membrane, and nucleic acids

29
Q

How does gas vapor destroy cells?

A

disrupting protein functions

30
Q

Chemical disinfectants that are effective against spores

A

Hydrogen peroxide
Chlorine dioxide
Chlorine

31
Q

How does alcohol destroy cells?

A

disrupts membrane bi-layers

32
Q

How does idoine destroy cells?

A

disrupts protein function and enzymes
(oxidizes essential enzymes)

33
Q

neutrophile pH

A

5-8 (most human pathogens)

34
Q

acidophile pH

A

0-5

35
Q

alkaliphiles pH

A

9-11

36
Q

what happens when cells are placed in pH conditions below the optimum?

A

protons can enter the cell and lower the internal pH to lethal levels

37
Q

How do cells prevent the influx of protons from low pH conditions?

A

exchange extracellular K+ for intracellular H+ (protons)

38
Q

the diffusion of fluid through semi permeable membrane from an area of low solute concentration to an area of high solute concentration

A

osmosis

39
Q

how do quartenary ammonium compounds kill cells?

A

disrupts membrane bi-layers
prevents bacteria from dividing

40
Q

how does soap and hot water kill cells?

A

Molecules of soap disrupt membrane bilayers by inserting themselves into membrane but they are not the same shape

41
Q

things to consider when choosing a chemical agent to clean (5)

A
  1. microbial susceptibility to the agent
  2. temp. and pH
  3. concentration of the agent needed
  4. environment (certain areas more sterile than others)
  5. endospore formers

Microbio (8 decks)

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