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Microbiology Unit 1 > Control of Microbial Growth > Flashcards

Control of Microbial Growth Flashcards

1
Q

What is the definition of Sterilization?

A

Removal of all microorganisms

~ Sterile item is absolutely free of microbes, endospores and viruses

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2
Q

What is the definition of Disinfection?

A

Eliminates most pathogens

~ Some viable microbes may exist

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3
Q

What is the definition of Pasteurization?

A

Brief heat treatment used to reduce organisms that cause food spoilage

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4
Q

What is the definition of Preservation?

A

Delaying spoilage of food by adding growth inhibition ingredients or adjusting storage conditions to impede growth

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5
Q

How can Sterilization be achieved?

A

filtration, heat, chemicals, and irradiation

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6
Q

How can Disinfection be achieved?

A

filtration, heat, chemicals, and irradiation

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7
Q

What are Disinfectants used to disinfect?

A

inanimate objects and surfaces

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8
Q

What are Antiseptics used to disinfect?

A

living tissues

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9
Q

What are the 4 physical methods of controlling microbial growth?

A
  1. Heat
  2. Irradiation
  3. Filtration
  4. Mechanical removal – “scrubbing”
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10
Q

What is the chemical method of controlling microbial growth?

A

By use of a variety of antimicrobial chemicals

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11
Q

Describe 3 methods of using moist heat for antimicrobial control.

A
  1. Boiling (100° C)
    ~ Destroys most microorganisms and viruses
    ~ does not destroy endospores
2. Pasteurization
~ Pasteur developed to avoid spoilage of wine
~ significantly reduces organisms
~ increases shelf life of food
~ Most protocols employ HTST method
(Heated to 72°C and held for 15 seconds)
  1. Pressurized steam - Autoclave
    ~ Achieves sterilization at 121°C and 15psi in 15 minutes
    (Effective against endospores)
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12
Q

Which is more effective for sterilization: moist or dry heat?

A

Moist heat

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13
Q

How does the Incineration method of dry heat sterilize?

A

It oxidizes the cells to ashes

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14
Q

What method of microbial growth control is used to destroy medical waste?

A

The Incineration method of dry heat sterilization

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15
Q

Hwo does liquid filtration work?

A

Membrane filters allow liquids to flow through but traps microbes on filter

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16
Q

What is liquid filtration used for?

A

Heat sensitive fluids

17
Q

Give an example of air filtration.

A

High efficiency particulate air (HEPA) filter removes microbes from air
~ Filter has 0.3µm pores to trap organisms

18
Q

Describe Electromagnetic radiation.

A

~ Shorter wavelength, higher frequency = more energy

~ Can be ionizing or non-ionizing

19
Q

Describe Ionizing radiation.

A

Radiation able to strip electrons from atoms

~ Causes damage to DNA and to plasma membrane

20
Q

What is Ionizing radiation used for?

A

Used to sterilize heat sensitive materials

ex. Medical equipment, surgical supplies, medications

21
Q

What is ionizing radiation most and least effective against?

A

Gram Negatives = most susceptible

Endospores = most resistant

22
Q

Describe Non-ionizing radiation (ultraviolet radiation).

A

Damages DNA by causing thymine dimers

23
Q

What is non-ionizing radiation most and least effective against?

A

Growing microorganism = most susceptible

Endospores = most resistant

24
Q

What is Non-ionizing radiation used for?

A

to destroy microbes in air, drinking water and surfaces

25
Q

What can limit non-ionizing radiation?

A

Thin films or coverings can limit effect (i.e., poor penetrating power)

26
Q

What are alcohols’ mode of action?

A
  1. Coagulation of proteins ands essential enzymes

2. Damage to lipid membranes

27
Q

What is the limitation of alcohol?

A

Evaporates quickly, limiting contact time

28
Q

What is alcohol not effective against?

A

endospores and some viruses

29
Q

What do aqueous solutions of 60% - 80% isopropyl or ethyl alcohol kill?

A

bacteria and fungi

30
Q

What is Halogen’s mode of action?

A

Oxidizing proteins and other cell components

31
Q

What does Chlorine destroy?

A

All microorganisms

32
Q

What are 2 examples of Halogens?

A

chlorine and iodine

33
Q

What does iodine destroy?

A

vegetative cells

34
Q

What is the active ingredient in Lysol and Amphyl?

A

Phenolics (carbolic acid)

35
Q

What is a Phenolic’s mode of action?

A
  1. Destroy plasma membrane

2. Denature proteins

36
Q

What can kill Mycobacterium at high concentrations?

A

Phenolics

37
Q

What are Quaternary Ammonium Compounds’ mode of action?

A
  1. Reduces surface tension
    ~ Aids in removal of dirt and organic matter
    ~ Facilitates mechanical removal of organisms
  2. Positive charge attracts Quats to negative charge of cell surface
    ~ Reacts with membrane
38
Q

What are Quats strong and weak against?

A
  1. Destroys vegetative bacteria and some viruses

2. Not effective on endospores, mycobacteria, and some viruses

Microbiology Unit 1 (11 decks)

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