Kozel: Sterilization, Disinfection, Containment

Question 1

use of physical or chemical agent to destroy all microbial forms, including spores

Answer 1

sterilization

Question 2

use of physical or chemical agents to destroy most microbial forms; bacterial spores or other relatively resistant organisms may remain viable

Answer 2

disinfection

Question 3

use of chemical agents on skin or other living tissue to inhibit or eliminate microbes; no sporicidal action is implied

Answer 3

antisepsis

Question 4

a general term describing a chemical agent, usually with a broad spectrum, that inactivates microbes

Answer 4

biocide

Question 5

Factors influencing disinfectant potency?

Answer 5

concentration - effective conc varies with disinfectant
time
pH
temp
microorganism

Question 6

What are the general categories of antimicrobial agents?

Answer 6

ethylene oxide and aldehydes
oxidizing agents
halogens
phenolic compounds
quaternary ammonium compounds
alcohols

Question 7

How do ethylene oxide and aldehydes work? Give an example

Answer 7

alkylate and cross-link macromolecules (DNA, RNA)

ex: formaldehyde - for environmental decontamination in gaseous form or dissolved in water

Question 8

How do oxidizing agents work? Give an example

Answer 8

they oxidize agents, cause DNA breakage

ex: ozone - for disinfection of air systems

Question 9

How do halogens work? Give an example

Answer 9

they oxidize proteins

ex - chlorine for chemical contamination

Question 10

How do phenolic compounds work? Give an example

Answer 10

they disrupt lipid containing membranes and denature proteins

ex: triclosan - in antibacterial soaps
chlorhexidine - skin infection

Question 11

How do quaternary ammonium compounds work? Give an example

Answer 11

surfactant - amphoteric properties disrupt membranes

ex: benzalkonium chloride - skin disinfection - hard surface cleaning (lysol)

Question 12

How do alcohols work? Give an example

Answer 12

they denature proteins

ex: isopropyl alcohol - skin decontamination and disinfection

Question 13

What is the problem with having antibacterial soaps everywhere?!

Answer 13

bacteria are becoming resistant

Question 14

What are three ways that bacteria resist disinfectants?

Answer 14

1. inactivation of the agent
2. efflux of the agent
3. decreased uptake

Question 15

At what temp are most pathogenic bacteria killed? At what temp are spores killed?

Answer 15

60C - hot water!

100C - boil them!

Question 16

What are some different means of heating microbes to kill them?

Answer 16

pasteurization - heating to 72C to decontaminate milk
boiling - 100C
autoclave - steam under pressure at 120C
dry heat - 180C
incinerator

Question 17

What are two physical means to kill or remove microbes?

Answer 17

UV radiation - there cannot be anything between the contaminated surface and the UV light
Ionizing radiation - Xray and gamma emitters
Filtration - will not remove small toxic or viral substances
HEPA air filters

Question 18

How to sterilize the following:

1. surgical dressing in package
2. decontaminate liquids that go down the sink
3. thermometer
4. sterilize site of lumbar puncture
5. disinfect skin at the site of a venipuncture
6. plastic pipettes in their wrappers

Answer 18

1. autoclave
2. autoclave or hit with bleach
3. alcohol
4. iodine
5. alcohol
6. ionizing radiation