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Micro-101 > Chap 7 - Control of Microorganisms: Phys and Chem > Flashcards

Chap 7 - Control of Microorganisms: Phys and Chem Flashcards

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0
Q

The destruction of all living microbes, spores and viruses.

A

Sterilization

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1
Q

When do sterile objects become contaminated?

A

When exposed to air and surroundings.

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3
Q

Does sanitization sterilize?

A

No. Sanitation reduces the number of pathogens or discourages their growth

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4
Q

Sanitization does what?

A

Reduces the numbers of pathogens. Lower level of control

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4
Q

What happens when microbes are at temperatures above their growth ranges?

A

Proteins and nucleic acids are destroyed, water is removed.

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5
Q

What is one of the most common physical control methods?

A

Heat

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6
Q

What method of heat uses direct flames to kill microbes?

A

Incineration

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7
Q

The minimum temperature to kill a species is considered what?

A

Thermal death point.

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8
Q

Thermal death time is what?

A

The length of time required to kill a microbial population at a given temperature.

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9
Q

Does hot air sterilization take a short time and does it penetrate?

A

No - it takes a long time and doesn’t penetrate

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10
Q

Dry and Moist Heat are applied similarly. (T/F)

A

False. Dry heat requires more time.

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11
Q

Name one tool used for incineration

A

Bunsen burner

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12
Q

Dry heat quickly burns the microbes. (T/F)

A

False - it slowly burns

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13
Q

Dry heat creates a moist environment. (T/F)

A

False - it creates an arid environment.

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14
Q

Dry heat creates an arid internal environment that changes microbial proteins by what?

A

Oxidation

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15
Q

Moist heat can be used to sterilize.

A

True

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17
Q

Boiling water kills all spores and inactivates all viruses.

A

False.

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18
Q

Which penetrates microbes better: dry heat or hot water?

A

hot water

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19
Q

Moist heat kills microbes by doing what?

A

Denaturing their proteins.

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20
Q

Autoclaves use what to kill microbes?

A

Steam, specifically Pressurized steam.

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21
Q

In Autoclaves, _______ increases as _______ increases.

A

Temperature, Pressure

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22
Q

This machine decreases the cycle time and exposure of sensitive materials to steam (creates saturated steam)

A

The prevaccum autoclave

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23
Q

If materials are not suited to the autoclave, what form of sterilization is used?

A

Fractional sterilization / intermittent sterilization (pg. 203)

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24
Q

Pasteurization is a form of _____ heat.

A

moist

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25
Q

What does pasteurization do?

A

Reduce bacterial populations in food and drink.

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26
Q

Why is pasteurization used in food & drink?

A

It reduces spoilage and disease. Kills pathogens and food spoilage organisms

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27
Q

Are bacterial spores affected by pasteurization?

A

No

28
Q

What is the only method of pasteurization used to sterilize liquid?

A

Flash pasteurization.

29
Q

In regard to filtration, how are microbes filtered? Viruses?

A

Pores, 0.2 micrometers which are smaller than most microbes. The average filter would allow viruses to pass through.

30
Q

Can viruses pass through pores?

A

Yes - they might be able to if they are smaller than 2 micrometers

31
Q

What does HEPA stand for?

A

High-efficiency particle air (filter)

32
Q

What kind of filter are used in hospitals?

A

HEPA Filters

33
Q

Can UV Light be used as a Microbial Control path?

A

Yes.

DNA of the cell absorbs the the UV light, causes adjacent thymine molecules to link together, kinking double helix

34
Q

UV light does what to microbial growth?

A

Remember: Disrupts DNA replications and transcription

Disruption in turn reduces population, limits airborne/surface contamination

35
Q

What are the types of radiation that can sterilize materials?

A

X Rays | Gamma Rays | Ionizing radiation

36
Q

This type of radiation forces electrons out of microbial molecules and is used in food products (pasteurizing dose)

A

Ionizing radiation

37
Q

Radiation for food is not used for shelf stability. (T/F)

A

False, it is used. Food is not sterile but removes chances of food born illnesses

38
Q

Bacteriostatic means what?

A

Slow multiplication of organisms. Anything with “-static” will reduce the numbers or inhibit growth. Others are: microbiostatic, fungistatic

39
Q

This form of preservation removes water necessary for microbes to live. (“where there is water, there is no life”)

A

Drying (used in meats, fish, cereals) ie beef jerky. Do not confuse with SALTING which is the DIFFUSION of water out of the cell.

40
Q

This form of preservation creates hypertonic environment (when water is diffused out of the cell) causes water loss from microbes then it will die.

A

Salting

41
Q

Does low temperatures (ie kept in refrigerator) also preserve food?

A

Yes - lower microbial metabolic and growth rates, retarding spoilage

42
Q

When did medicinal chemicals come into widespread use? By who?

A

In the 1800s & Lister

43
Q

What is the definition of “disinfectant”?

A

chemical used to kill or inhibit pathogenic microorganism on a lifeless object such as a tabletop.

44
Q

Disinfectants are used on ____, while antiseptics are used on ____.

A

Surfaces/Objects | Skin

45
Q

Microbicidals do what?

A

Inactive enzymes of organisms; interferes with metabolism. Kill!!!

46
Q

De-germing means what?

A

removing organisms from an object’s surface.

47
Q

Hand-soap has a pH of what?

A

12

48
Q

To be a useful as a disinfectant or antiseptic it should:

A 
• Kill or slow growth of microbes and
be non-toxic to animals or humans
• Be soluble in water or alcohol, and
easy to apply
• Have a relatively long shelf life
• Be used in a diluted form
• Act in a short time
• Be non-staining and non-corrosive
(doesn’t burn skin)
• Be odorless, easy to obtain
• Be relatively inexpensive
49
Q

What are things to consider with chemical agents at disinfectants or antiseptics?

A
  1. Microbial susceptibility - leave the solution to kill on long enough.
  2. Temperature and pH – consider temp of are
    cleaning, temp/ph can change reaction to disinfectant.
  3. Concentration- higher conc more effective.
  4. Environment – bioburden, more organisms present longer it takes to clean.
  5. Endospore formers
50
Q

Thermal death time is what?

A

The time needed to kill the species.

51
Q

What is the thermal death point of E. Coli

A

55 mins to 2 hours (320F / 160C)

52
Q

When using a chemical should you concern yourself with how long to leave the solution on the surface?

A

Yes. Microbial susceptibility is different for each organism. You must take this into consideration.

53
Q

Does the temperature of a room effect the growth or organisms?

A

Yes.

54
Q

Can you kill endospores by boiling them?

A

The only sure way to rid of spores is to use an autoclave or incineration.

55
Q

What is the phenol coefficient?

A

Indicates disinfecting ability. Everything is compared to phenol which is given a 1.

56
Q

Is a phenol coefficient of 2 or 200 better? How about .04? Which one is most effective?

A

.04 is worse than phenol. 200 is better than 2.

57
Q

What do we look for when using the disk diffusion method for testing effectiveness of a chemical?

A

zone of inhibition

58
Q

True or False: Chlorine is used in municipal water supplies?

A

True!

59
Q

True or False? Iodine is used to clean wounds.

A

True

60
Q

What is the purpose of iodopors?

A

release idodine over a long period of time.

61
Q

Chemical agents that contain _________ __________, cross link proteins together so they can no longer function.

A

Heavy Metals

62
Q

Chemicals containing __________ denature proteins and disrupt the membrane (dissolve lipids)

A

Alcohol

63
Q

Which is more effective: 70% alcohol hand sanitizer or 90%? Why?

A

70% because it evaporates slower than 90%

64
Q

mechanically remove organisms from a surface

A

degerm

65
Q

_________ emulsify and solubilize particles clinging to a surface.. An example is soap.

A

Surfactants

66
Q

A strong surfactant that alters the membrane and cause cell lysis

A

detergent

67
Q

How does soap removes organisms from your hands?

A

Soap has a positive charge. Bacteria has a negative charge. Soap surrounds bacteria!

Micro-101 (7 decks)

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