Chapter 9: Control of Microbial Growth- Part 2

Question 1

Filtration of fluids

Answer 1

Nylon membranes of defined pour sizes

• 0.45 um
• 0.20um

Question 2

How are the filters sterilized for filtration of fluids?

Answer 2

Irradiation

Question 3

What does filtration of fluids filter out?

Answer 3

Bacteria but NOT viruses or prions

Question 4

HEPA

Answer 4

High-efficiency particulate air filters

Question 5

HEPA uses

Answer 5

• Room ventilation
• Laminar flow hoods
• Powered Air-Purifying Respirator (mask covering face)

Question 6

Types of radiation

Answer 6

Ionizing
Ultraviolet
Microwaves

Question 7

Ionizing radiation

Answer 7

Damages things by causing electrons to pop off

Question 8

UV light

Answer 8

Can be damaging to DNA

Question 9

Microwaves

Answer 9

Use hear as a way to destroy things

Question 10

High pressure

Answer 10

Like an autoclave without the heat or steam (up to 130,000 psi)

Question 11

Potency

Answer 11

How well something gets rid of microorganisms

Question 12

Levels of potency

Answer 12

Sterilants
High-level disinfectants
Intermediate-level disinfectants
Low-level disinfectants

Question 13

Sterilants

Answer 13

Kills everything!

Question 14

High-level disinfectants

Answer 14

Kills viruses and all vegetative bacteria (but not spore formers!)

Question 15

Intermediate-level disinfectants

Answer 15

Kills all vegetative bacteria and most viruses

Question 16

Low-level disinfectants

Answer 16

All vegetative bacteria and enveloped (membrane-bound) viruses

Question 17

Which type of viruses are more/very hardy?

Answer 17

Non-enveloped

Question 18

Why are sterilants not always used?

Answer 18

They could damage what you are trying to clean, cost, etc.

Question 19

You have been given a sample of one type of bacteria and one virus and have been asked to kill the bacteria and inactivate the virus using the least potent chemical treatment to do so. The bacteria do not produce endospores and the virus is enveloped. What would you use?

Answer 19

Low-level disinfectant

Question 20

Things to consider when selecting the appropriate germicidal chemical

Answer 20

Toxicity
Activity in the presence of organic matter
Residue
Cost and availability
Storage and stability
Environmental risk

Question 21

Germicidal

Answer 21

Killing bacteria and inactivating viruses

Question 22

Chemical classes of germicidal chemicals

Answer 22

Alcohols 
Aldehydes
Biguanides
Ethylene oxide
Halogens
Ozone
Peroxygens
Phenolic compounds
Quaternary ammonia

Question 23

Alcohols

Answer 23

Denature proteins, solubilize membranes (can be used as antiseptics and disinfectants)

Question 24

Aldehydes

Answer 24

Chemically modify proteins and nucleic acids

Question 25

Glutaraldehyde

Answer 25

2% solution used on medical instruments that are heat sensitive

Question 26

Formaldehyde

Answer 26

Gas used to fumigate (especially areas with airborne viruses, cruise ship)

Question 27

Orthophthaladehyde

Answer 27

OPA, newer aldehyde, has shorter contact time

Question 28

Biguanides

Answer 28

Adhere to skin and mucous membranes

Question 29

Biguanides are a type of...

Answer 29

Antiseptic

Question 30

Biguanides target...

Answer 30

Membranes for destruction

Question 31

Chlorhexidines

Answer 31

Type of biguanide, antiseptic ointment or solution - Surgical scrubbing - Mouthwash - Skin abrasions

Question 32

Ethylene oxide

Answer 32

For use on substances that can not withstand autoclaving, used on surgical garbs

Question 33

What does ethylene oxide do?

Answer 33

It is highly oxidative, destroys DNA

Question 34

Halogens

Answer 34

Target proteins, react with organic molecules to form toxic substances

Question 35

Examples of halogens

Answer 35

Chlorine Wescodyne Iodine- not effective against endospores and Pseudomonas species (only effective against what is common)

Question 36

Ozone

Answer 36

Target proteins, oxidative agent

Question 37

Ozone is used for..

Answer 37

Drinking water and wastewater (usually the last step in many water treatment plants)

Question 38

Peroxygens

Answer 38

Target proteins | Oxidizing agents

Question 39

Examples of peroxygens

Answer 39

``` Hydrogen peroxide (H2O2) Peracertic acid ```

Question 40

Phenolic compounds

Answer 40

Dissolve membranes Denature proteins -Lysol

Question 41

Quaternary ammonia compounds

Answer 41

Research labs and food preparation areas | Cationic detergents

Question 42

What do quats do?

Answer 42

Bind to negatively-charged membrane lipids

Question 43

Chemicals that target cytoplasmic membrane

Answer 43

Biguanides Phenolics Quats

Question 44

Chemicals that target DNA

Answer 44

Ethylene oxide | Aldehydes

Question 45

Chemicals that target proteins

Answer 45

``` Alcohols Aldehydes Halogens Metals Ozone Peroxygens Phenolics ```