Culture-based diagnostic and typing methods

Question 1

What is microscopy and staining used for?

Answer 1

Detect bacterial cells, fungal elements, parasites, inclusion in cells

Question 2

How are fungi stained?

Answer 2

Calcofluor white (CFW) non-specifically binds to chitin and cellulose in cell wall
- fluoresces bright green-blue

Question 3

What are the types of medias?

Answer 3

Non-selective
Supplemented (chocolate agar)
Differential (blood agar)
Chromogenic

Question 4

Describe selective media

Answer 4

Non-sterile sites
Supplemented with antimicrobial/inhibitors
- restricts commensals growth

Question 5

Describe differential media

Answer 5

Highly distinctive metabolic activities
Carbohydrate source use -> acid -> pH change
Medium uses pH indicator and carbohydrate source

Question 6

Describe chromogenic media

Answer 6

Chromogenic enzyme substrates hydrolysed in presence of specific microbial enzymes

Question 7

Give examples of biochemical testing

Answer 7

a.a metabolism
carbohydrate oxidation/fermentation
utilisation of carbon source
nitrate reductase