Sterilization, Disinfection

Question 1

What is sterilization?

Answer 1

Process that aims to destroy all microbes within a medium.

The goal is to have a total germ-free state.

Question 2

List the uses of an open flame in sterilization methods

Answer 2

• burning –> dead lab animals, infectious waste
• cauterization –> lab glassware
• white heating –> inoculation loops

Question 3

How does heat sterilize?

Answer 3

VIA:

• protein destruction
• hydrolysis
• oxidation

Question 4

What is sterilized in a dry heat chamber?

Answer 4

• glassware
• tools without fine edge
• powders
• oils

Question 5

What are the temperatures used in dry heat chambers?

Answer 5

180 degrees –> for 1 hr
160 –> For 2 hrs
140 –> For 3 hrs

Question 6

What is prohibited in dry heat chambers?

Answer 6

• water-based solutions
• textiles
• rubberware
• plastic tools
• instruments made of materials with different heat tolerance

Question 7

What is an autoclave?

Answer 7

A pressure chamber used to carry out sterilization with high heat and saturated elevated pressure steam for a longer period of time.

Question 8

What are the normal autoclave parameters?

Answer 8

• 121 degrees celcius for 20-30 min (+1atm)
• 134 degrees celcius for 10 min (+2 atm)

BUT for prions, they require:
- 2NaOH for 1 hr 
OR
-1NaOH for 2 hrs
and
134 degrees celcius for 1 hour (+2atm)

Question 9

List the phases of the work process of an autoclave

Answer 9

1) warming up phase
2) equalization phase
3) sterilization phase
4) cooling down phase

Question 10

List the sterilization methods based on radiation:

Answer 10

• gamma radiation

- UV-radiation (200-400 nm)

Question 11

Name gas sterilization.

Answer 11

-formaldehyde, ethylene oxide

Question 12

What is the definition of disinfection?

Answer 12

Reducing the number of infectious microorganisms to an amount that they cannot incite infection

Question 13

What are antiseptics used for?

Answer 13

They are disinfectants used on living tissue/skin to reduce possibility of infection or sepsis

Question 14

What does it mean to be bacteriostatic?

Answer 14

To inhibit bacterial reproduction

** Does NOT kill them!

Question 15

List examples of bacteriostatic antibiotics:

Answer 15

• chloramphenicol
• erythromycin
• clindamycin
• tetracyclins
• sulfonamides

Question 16

What does it mean to be bactericidal?

Answer 16

To kill a proportion of microbes in a given amount of time

Question 17

List examples of bactericidal antibiotics:

Answer 17

• aminoglycosides
• beta-lactams
• vancomycin
• quinolones
• rifampin
• metronidazole

Question 18

What does asepsis mean?

Answer 18

The absence of bacteria, viruses and other microorganisms

Question 19

What is the aim of asepsis?

Answer 19

To prevent contamination caused by microorganisms i.e. sterilization of surgical instruments

Question 20

What is the aim of anti-sepsis?

Answer 20

To neutralize already existing contamination caused by microorganism

Question 21

List factors that influence efficiency of disinfectants:

Answer 21

• quality of surface
• temperature, pH
• hardness of water
• germ number
• resistance of microbes
• microbes ability to inactivate the chemical

Question 22

What is the MIC (minimal inhibitory concentration)?

Answer 22

The lowest concentration of drug that has an inhibitory (bacteriostatic) effect

Question 23

What is the phenol coefficient?

Answer 23

It’s a measure of bactericidal activity of a chemical compared to the compound phenol