Chapter 11 Sterilization

Question 1

What is the mechanism of action of iodine/iodophors?

Answer 1

Cell wall penetration, oxidation via free iodine which denatures proteins

Question 2

Define sterilization

Answer 2

Process of destroying all microorganisms on or in an object

Question 3

Define disinfection

Answer 3

Destruction of most pathogenic microorganisms except for spores, anything less than sterilization

Question 4

Define antiseptic

Answer 4

Diminishing pathogenic microorganisms to an acceptable level

Question 5

What is the mechanism of action of steam sterilization?

Answer 5

Kills microorganisms through coagulation and denaturation of proteins by moist heat

Question 6

Steam sterilization is efficacious against spores TRUE or FALSE

Answer 6

True

Question 7

What temperature and times are recommended for steam sterilization with a gravity-displacement unit versus a prevacuum unit?

Answer 7

Gravity-displacement: 121 degrees Celsius for 30 minutes with 15-30 minutes drying time
Prevacuum: 132 degress Celsius for 4 minutes with 15-30 minutes drying time

Question 8

Dry sterilization requires a ____ temperature and ____ exposure

Answer 8

Higher temperature, longer exposure times

Question 9

How should you store bowls for steam sterilization?

Answer 9

Facing down, will trap cool air if facing up

Question 10

What is the mechanism of action of ethylene oxide sterilization?

Answer 10

Alkylation of proteins and nucleic acids obstructs cell metabolism and reproduction

Question 11

Why is aeration needed for certain materials sterilized with ethylene oxide?

Answer 11

Ethylene oxide gets absorbed and can become toxic (eg. rubber and plastics)

Question 12

What is the sterilization time of ethylene oxide?

Answer 12

2-5 hours + aeration

Question 13

What is the mechanism of action of plasma sterilization?

Answer 13

• Uses electromagnetic energy to create plasma phase from vapor of H2O2, O2, or peracetic acid/H2O2 mixture
• Plasma contains reactive products (ie. free radicals) that deactivate cellular processes

Question 14

What temperature and cycle time is recommended for plasma sterilization?

Answer 14

45-50 degrees Celsius for 28-75 minutes

Question 15

What items is plasma sterilization useful for?
What should it not be used for?

Answer 15

Useful for: Moisture- and heat-sensitive items
Should not be used for: linens, wood, liquids

Question 16

Advantages of plasma sterilization?

Answer 16

1. Short cycle time
2. Ability to sterilize heat- and moisture-sensitive items
3. Lack of toxic residues (no aeration when using H2O2)

Question 17

After autoclaving, small instruments can be stored at least ___ weeks when double layered in linener or plastic-paper envelope

Answer 17

96 weeks

Question 18

How long can you store plastic wrap tape sealed items sterilized by ethylene oxide?

Answer 18

90-100 days

Question 19

How long can you store paper wrapped items sterilized by ethylene oxide?

Answer 19

30-60 days

Question 20

How long can you store heat-sealed plastic wrap items sterilized by ethylene oxide?

Answer 20

One year

Question 21

What are physical sterilization indicators?

Answer 21

Physical monitors that print out graphs verifying temperature and time

Question 22

What are the 6 classes of chemical indicators?

Answer 22

1. Indicates pack has been processed but limited concrete information about parameters met (ie. sterilization tape outside of pack)
2. Test for air removal (Bowie-Dick tests)
3. React to specific parameter such as temperature or time
4. React to more than one parameter
5. React to all parameters that are important to a given type of sterilization
6. Designed to monitor more specific guidelines associated with a unique indication

Question 23

Which class of indicator would be used to combat prion infection?

Answer 23

Class 6

Question 24

What is a biologic indicator?

Answer 24

Culture for microorganisms post-processing, takes 16 hours - 7 days

Question 25

What bacteria is used as a biologic indicator for steam/plasma/ozone sterilization? Ethylene oxide?

Answer 25

Steam/plasma/ozone = *Geobacillus stearothermophilus* Ethylene oxide = *Bacillus atrophaeus*

Question 26

Vacuum sterilization uses dry heat and uses a temperature of 132 degrees for 4 minutes **TRUE** or **FALSE**

Answer 26

False, uses steam

Question 27

Which of the following has the most **residual activity**? 1. Chlorhexidine 2. Povidone iodine 3. Alcohol 4. Triclosan

Answer 27

Chlorhexidine ## Footnote Alcohol has no residual activity, iodine moderate, triclosan intermediate

Question 28

What areas should povidone-iodine be used as surgical preparation?

Answer 28

Ears, mouth, and eyes

Question 29

How does povidone-iodine work?

Answer 29

Disorders proteins, blocks protein synthesis, alters cell membrane ## Footnote Poor to acceptable against spores with moderate residual activity, reaction in 50% cases

Question 30

How does chlorhexidine work?

Answer 30

Disrupts cell membrane

Question 31

Chlorhexidine is ___ at high concentrations and ___ at low concentrations

Answer 31

Bactericidal at high concentrations - interferes with cell membranes Bacteriostatic at low concentrations - coagulation of cell contents

Question 32

What chlorhexidine solution % should be used in wounds?

Answer 32

<0.05%

Question 33

**TRUE** or **FALSE** Chlorhexidine can be used for otic preparation

Answer 33

False, is ototoxic in middle ear

Question 34

What happens if chlorhexidine diacetate is mixed with saline?

Answer 34

Forms a precipitate

Question 35

How long is a **cloth-wrapped** item sterile for after ethylene oxide gas sterilization?

Answer 35

15-30 days