Microbiology: Fungal Culture

Question 1

What parasite is this?

1. superficial mycosis
2. ringworm
3. must be differentiated from mite infestation or hypersensitivity reactions

Answer 1

Dermatophytes

Question 2

What type of dermatophyte is zoonotic?

Answer 2

superficial mycosis

Question 3

What type of dermatophyte is this?

1. subclinical in kittens and rodents
2. typical ringed lesions
3. nodular or tumorous lesions
4. can cause hair loss and skin irritation

Answer 3

ringworm

Question 4

What are these media or tests used for?

1. Wood’s Lamp
2. Direct Microscopy
3. Fungal Culture

Answer 4

ID of ring worm

Question 5

What method of ringworm identification is this?

1. 50% of positive cases will fluoresce
   - Microsporum canis (very common)
2. However, if treated with topicals may get spurious fluorescence (false positive)

Answer 5

Wood’s Lamp

Question 6

What method of ringworm identification is this?

1. Look at hair under microscope
2. Pluck hairs, do not cut
3. Skin scrape at lesion’s edge until it oozes blood
4. Place drop of 20% KOH solution or lactophenol cotton blue
5. Will see highly refractile arthrospores at root of hair

Answer 6

Direct Microscopy

Question 7

What method of ringworm identification is this?

1. Sabourauel dextrose agar and pH indicator
2. Low pH (5-6) inhibits most bacterial growth, promotes fungal growth
3. Alkaline metabolites change color to red
4. Colony morphology

Answer 7

Fungal Culture