Pharmaceutical Microbiology

Question 1

What are the 4 methhods for counting bacteria?

Answer 1

• Direct Microscopic Counts (flourescent dyes)
• Plate count (serial dilution)
• The most propbable number
• Indirect number (spectroscopy)

Question 2

Describe the Tube Dilution Assay Test.

Answer 2

Test the effectiveness of Antimicribial agent

1) Serial Dilution of antimicrobe with microbe
2) lowest concentration of anti microbe that kills bacteria is the minimal inhibitory concentration

Question 3

What are the 2 tests for antimicrobial effectiveness?

Answer 3

• Tube dilution assay
• Disc diffusion method (discs preventing microbe growth on a plate)

Question 4

Give 4 methods of physical sterilisation.

Answer 4

• Heat (moist and dry)
• Pressure
• Sound
• Filtration
• Irradiation

Question 5

What are the differences between gram-negative and gram-positive bacteria?

Answer 5

• Gram-negative bacteria have thinner peptidoglycan layer
• Gram-negative bacteria contain lipoprotein layer and polysaccharide layer

Question 6

Which type of bacteria retain methyl violet stain?

Answer 6

gram-positive

Question 7

Describe the bacterial growth curve.

Answer 7

1) Lag Phase - no. of bacteria doesn’t increase, cell size increases

2) Exponential Phase - no. of bacteria exponentially increases

3) Stationary Phase - not of cells dying = no. of cells increasing

4) Death Phase - no. of cells dying is greater than cells increasing

Question 8

What are 4 factors effecting microbial growth?

Answer 8

• Temp
• pH
• Light
• Oxygen
• Osmotic pressure