Lecture 13 Flashcards

1
Q

Sterilization

A

all microorganisms dead (even endospores)

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2
Q

Pasteurization

A

reduce the number of microbes

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3
Q

Disinfection

A

most pathogens dead

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4
Q

Decontamination

A

reduce pathogens to a “safe” level (disease causing)

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5
Q

Sanitization

A

reduce all organisms to a “safe” level (includes even non-disease causing)

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6
Q

Know three bacterial structures

A

Endospores
Protist Cyst
Enveloped Viruses

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7
Q

Know one bacterial or eukaryotic structure that are hard to kill

A

Endospore

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8
Q

Know why naked viruses are harder to kill than enveloped viruses

A

resistant to drying and disinfectants, protein shell is very tough

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9
Q

What is water activity?

A

moisture content = vapor pressure of material / vapor pressure above pure water

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10
Q

What organisms survive best at low water activity

A

fungi like xerophilic fungi

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11
Q

What is decimal reduction time?

A

amount of time required to decrease by 1 order of magnitude (1 tenfold reduction)

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12
Q

How does decimal reduction time depend on the organism that is being killed?

A

more organisms (or biofilms) = more disinfectant time

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13
Q

How does decimal reduction time depend on the surface being decontaminated?

A

heat-sensitive, moisture-sensitive shouldn’t be sprayed
bleach cannot be used on metal

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14
Q

How does decimal reduction time depend on the decontaminant used?

A

combined procedures = less time

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15
Q

Critical medical instrument

A

direct contact with body tissue

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16
Q

Semicritical medical instrument

A

contact with mucous membranes

17
Q

Noncritical medical instrument

A

external contact only

18
Q

Why is moist heat more effect as a decontaminant than dry heat?

A

it is much more penetrating than dry heat, because of the high heat capacity of water

19
Q

How does an autoclave function?

A

uses steam and pressure to reach a temperature of 121, has steam supply and exhaust pipe

20
Q

What are three methods that are used to pasteurize liquids?

A
  1. Batch Pasteurization (63C for 30 minutes)
  2. Flash Pasteurization (72C for 15 seconds)
  3. Ultra pasteurization (150C for 1 sec)
21
Q

What is the difference between a membrane filter and a depth (HEPA) filter?

A

Membrane filter: 0.2um pore (virus pass through)
HEPA filter: uses filter matrix

22
Q

What types of radiation can be used to kill bacteria? What cannot?

A

Ionizing radiation (X-rays, gamma rays) and UV rays can kill bacteria

microwaves cannot

23
Q

What three bacterial structures that can serve as targets for chemical disinfectants.

A
  1. Cytoplasmic membrane
  2. Protein
  3. DNA
24
Q

What is the mode of action for alcohol?

A

damage lipid membranes and denature proteins

25
What is the mode of action for aldehydes?
crosslink and rigidify proteins
26
What is the mode of action for chlorhexidine?
makes membranes leaky
27
What is the mode of action for ethylene oxide?
gaseous sterilant; oxidize DNA
28
What is the mode of action for halogens?
oxidize proteins
29
What is the mode of action for heavy metals?
derivatize cysteine to prevent protein disulfide bonds
30
What is the mode of action for peroxide?
oxidize proteins
31
What is the mode of action for phenols?
dissolve lipid membranes
32
What is the mode of action for quaternary amines?
dissolve membranes
33
What happened in Milwaukee in 1993?
water treatment plant had bad filters, crypto cysts caused people to get diarrhea
34
How was the overuse of triclosan led to increased bacterial resistance?
triclosan was acting like an antibiotic, so when they adapted they became resistant to triclosan and other antibiotics