Sterilization, Disinfection, & Antisepsis- RA1

Question 1

Why are sterilization, disinfection, & antisepsis needed to prevent Hospital Acquired Infections (HAI)?

Answer 1

• Hospital acquired infections can lead to:
  ○ Serious illness or death
  ○ Extended stay & consequent loss of earnings/ hardship
  ○ Transmission of infection to other patients
• Studies indicate that 1/3 of hospital acquired infections are preventable
• Sterilization, disinfection & antisepsis are methods of preventing hospital acquired infections

Question 2

Define sterilization.

Answer 2

Total destruction or physical removal of ALL microorganisms

Question 3

List the most common methods of sterilization.

Answer 3

• Moist Heat
• Dry Heat
• Ethylene Oxide Gas
• Irradiation

Question 4

Describe the mechanism of moist heat in sterilization.

Answer 4

Saturated steam under pressure (e.g. autoclave) kills microbes by irreversibly denaturing proteins, causing single strand DNA breaks & compromising membrane integrity

Question 5

Describe the mechanism of dry heat.

Answer 5

Oven that kills microbes by irreversibly denaturing proteins, causing single strand DNA breaks & compromising membrane integrity

Question 6

Describe the mechanism of ethylene oxide gas.

Answer 6

Kills by alkylating proteins, DNA, & RNA within cells, which prevents normal cellular metabolism & replication

Question 7

Describe the mechanism of irradiation.

Answer 7

UV & Gamma Rays that kill by eliciting DNA damage through production of free radicals; blocking microbial replication

Question 8

What is the definition of disinfection. How is disinfection different from sterilization?

Answer 8

• Disinfection= process of removing or killing most, but NOT all viable organisms
• Sterilization removes all organisms

Question 9

What are the three categories of disinfection?

Answer 9

• High level
• Intermediate level
• Low level

Question 10

What is the definition of high level disinfection?

Answer 10

High quality method that can approach sterilization; kills all but large bacterial spores–used for instruments & devices that cannot be sterilized

Question 11

What is the definition of intermediate level disinfection?

Answer 11

Can kill most microorganisms but NOT effective against bacterial spores at all–used on semi-critical instruments that cannot be sterilized

Question 12

What is the definition of low-level disinfection?

Answer 12

Kills most vegetative bacteria, some fungi, & some viruses– used on non-critical instruments e.g. stethoscopes, BP cuffs…etc.

Question 13

List the high level disinfection agents.

Answer 13

Glutaraldehyde
Peracetic acid
Hydrogen peroxide
Chloine compounds (bleach)

Question 14

List the intermediate level disinfection agents.

Answer 14

Alcohols
Iodine
Phenolic compounds

Question 15

List the low level disinfection agents.

Answer 15

Quaternary ammonium

Question 16

What is antisepsis?

Answer 16

Disinfectants are used to lower the number of microorganisms on skin surfaces

• None kill bacterial spores but do kill vegetative bacteria
• Are generally very safe

Question 17

What is the most common & effective method for skin antisepsis for blood culture?

Answer 17

Iodine containing solutions

Question 18

What are the two major iodine containing compounds?

Answer 18

1) Tincuture of iodine

2) Iodophors

Question 19

Describe the mechanism of action of iodines.

Answer 19

Penetrates the cell wall of microorganisms & causes disruption of proteins, nucleic acid structure, & synthesis.

Question 20

What are the two most highly resistant organisms to methods of disinfection & antisepsis?

Answer 20

1) Prions

2) Bacterial spores