Lecture 2

Question 1

Two types of culture media

Answer 1

1. Ready made culture media
2. In-house culture media

Question 2

Ready Made culture media

Answer 2

1. Stringent QC tests
2. QC to accompany each batch
3. Expensive

Question 3

In-house culture media

Answer 3

1. Automated systems
2. Manual
3. QC not expensive
4. Small batches

Question 4

Dehydrated media

Answer 4

1. This is hydroscopic
2. Sensitive to light, heat and moisture
3. Affected by drastic changes in temperature
4. Important to have the right storage conditions

Question 5

Preparation of dehydrated media

Answer 5

1. Write date of receipt / date 1st opened
2. Store as directed on label
3. Check expiry date ( do not use beyond it )
4. Order in small batches
5. Use a clean, dry spatula to weigh amount required

Question 6

Summary of preparing a culture media

Answer 6

Weigh powder –> Add water –> Mix –> Boil –> Sterilise –> Cool –> Dispense –> QC –> Use

Question 7

Sterilisation cycle

Answer 7

1. Chamber heat-up time
2. Heat penetration of the medium container
3. Holding time at prescribed temperature
   4.Cool-down for chamber to reach 80 degrees Celsius

Question 8

Temperatures at each stage

Answer 8

Stage 1 : 80 - 100 degrees celsius
Stage 2 : 100 - 121 degrees celsius
Stage 3 : 121 -121 degrees celsius
Stage 4 : 121 - 80 degrees celsius

Question 9

Preparation of sterilised liquid media

Answer 9

1. Cool down to room temperature
2. Tighten screw caps

Question 10

Preparation of sterilised solid media

Answer 10

1. Place in a water bath at 50 degrees celsius
2. Supplements should be at room temperature
3. Blood should be warmed at 35-37 degrees celsius
   (medium should be cooled at 40-45 degrees celsius)

Question 11

3 Types of Petri Dishes

Answer 11

1. No vents
2. Single vent
3. Triple Vents

Question 12

McCartney Bottles

Answer 12

Universal bottle - 28 mls
McCartney container Bijoux - 7 mls
McCartney container - 14 mls
McCartney container - 28 mls