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STERILIZATION AND DISINFECTION

CHAPTER 12

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Terminology

Disinfection- reduction of number

– Disinfectant used on inanimate objects (most do not kill spores)

– Antiseptic can be used on skin

Sterilization (Autoclave)20 mins at 121 degrees and 18 PSI

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Chemical Antimicrobials Potency

Phenol coefficient

Filter paper method

Use dilution test

mic: minimum inhibitory conc

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Microbial Sidebar 27-2

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Disinfectant Selection Criteria Time of action

Safety

Microbe range

Penetration

Preparation

Cost

Odor

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Mechanisms of Action Protein damage

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Mechanisms of Action

Membrane damage

Other

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Disinfectant Types Soaps/detergents

Acids/Alkalis

Heavy Metals

Halogens

Such as mercury

Such as iodine, bromineand chlorine

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Disinfectants (cont.) Alcohols

Phenolics

Oxidizers

Alkylating agents

Dyes

Peroxides

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Alkylating agents

Ethylene oxide

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Physical Antimicrobial Agents Heat Application

– Dry Heat

– Moist Heat

– Pasteurization

171 deg, 1 hr

62.9 for 30 mins

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The Autoclave

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Fig. 27-1

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Time (min)

Su

rviv

al f

ract

ion

(lo

g s

cale

)

20 30 40 50

60°C

70°C

50°C

Decimalreductiontime (D)

100

10

1

0.1

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Fig. 27-3

Tem

per

atu

re (

°C)

100

110

120

130

Total cycle time (min)

0 10

Temperatureof object beingsterilized

20 30 40 50 60

Temperatureof autoclave

Sterilization time

Autoclave time

Stopsteam

Beginpressure

Flowingsteam

Steam supplyvalve

Steam enters here

Thermometerand valve

Steamexhaustvalve

Chamberpressuregauge

Air exits through vent

Jacket chamber

Steam exhaust

Door

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Physical Antimicrobial Methods

Refrigeration/Freezing

Dessication

Freeze-drying

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Physical Antimicrobial Methods

Radiation

Filtration

0.45 micron

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Fig. 27-4

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Physical Antimicrobial Methods

Osmotic Control

Sugar or salt