Disinfectants

Question 1

How would you use thermal treatment to destroy prions?

Answer 1

Autoclave at 134 degrees on repeat cycles

Question 2

Describe pasteurisation and what it achieves

Answer 2

NOT stertilisation
Rapid heating and then rapid cooling
Reduces number of sensitive, viable and vegetative bacteria

Question 3

Define disinfection

Answer 3

Descruction of microorganisms by physical and chemical methods on the surface of objects

Question 4

Define antisepsis

Answer 4

Distruction of micro-organisms on tissues using non toxic and non irritant methods and substances

Question 5

Describe the ideal chemical disinfectant

Answer 5

• Broad Activity
• Absence of irritancy or toxicity, noncorrosive and non polluting
• Long shelf life, stable
• Soluble in water and compatible with other chemicals
• Active in organic matter and over a range of temperatures

Question 6

Describe Prions

Answer 6

Type of protein that triggers proteins in the brain to fold abnormally - causes neurological disease

• Non living
• Difficult to get rid of (high autoclave temperature for 4.5 hrs)

Question 7

Describe the mode of action of acidic disinfectants

Answer 7

Destroys nucleic acid bonds and precipitate proteins

Question 8

What can acidic disinfectants be used against?

Answer 8

Mycoplasma
Gram +ve
Gram -ve
Enveloped viruses

Question 9

Describe the mode of action of alcohol

based disinfectants

Answer 9

Denatures proteins and causes membrane damage

Question 10

What can alcohol based disinfectants be used against?

Answer 10

Mycoplasma
Gram +ve 
Gram -ve
Enveloped viruses 
ACID FAST BACTERIA

Question 11

Describe the mode of action of alkaline disinfectants

Answer 11

Saponify lipids in cell membranes and envelopes (activity increases with temperature)

Question 12

What can alkaline based disinfectants be used against?

Answer 12

Mycoplasma
Gram +ve
Gram -ve 
Enveloped Viruses
FUNGAL (+BACTERIAL) SPORES
ACID FAST BACTERIA
COCCIDIA(parasite)

Question 13

Describe the mode of action of aldehyde disinfectants

Answer 13

Denature proteins and nucleic acids

Question 14

What can aldehyde based disinfectants be used against?

Answer 14

Mycoplasma
Gram +ve
Gram -ve 
Enveloped Viruses
NON ENVELOPED VIRUSES
FUNGAL (+BACTERIAL) SPORES
ACID FAST BACTERIA

Question 15

Describe the mode of action of biguanide disinfectants

Answer 15

React with negatively charged groups in cell membranes altering permeability

Question 16

What can aldehyde based disinfectants be used against?

Answer 16

Mycoplasma
Gram +ve
Gram -ve

Question 17

Describe the mode of action of halogen compound disinfectants

Answer 17

Chlorine - denatures proteins

Iodine - denature proteins

Question 18

What can halogen compound based disinfectants be used against?

Answer 18

Chlorine 
- Mycoplasma
- Gram +ve 
- Gram -ve 
- Enveloped viruses 
- NON ENVELOPED VIRUSES 
- FUNGAL AND BACTERIAL SPORES
- ACID FAST BACTERIA
Iodine
Same as chlorine without non enveloped viruses

Question 19

Describe the mode of action of phenolic compound disinfectants

Answer 19

Broad spectrum function by denaturing proteins (often formulated with soaps to increase penetration)

Question 20

What can phenolic compound based disinfectants be used against?

Answer 20

Mycoplasma
Gram +ve 
Gram -ve 
FUNGAL SPORES
COCCIDIA(parasite)

Question 21

Describe the mode of action of quaternary ammonium compound disinfectants

Answer 21

Irreversibly bind phospholipids and proteins effecting cell permeability

Question 22

What can quaternary ammonium compound based disinfectants be used against?

Answer 22

Mycoplasma
Gram+ve
Gram -ve

Question 23

Describe the mode of action of oxidising agent disinfectants

Answer 23

Denatures proteins and lipids

Question 24

What can oxidising agent based disinfectants be used against?

Answer 24

Mycoplasma
Gram +ve 
Gram -ve 
Enveloped viruses 
BACTERIAL SPORES