Fungal infections and antifungals

Question 1

Give two reasons why fungal infections can be difficult to diagnose

Answer 1

• Slow growing

- Can be masked by bacteria

Question 2

Give two ways of classifying fungal infections

Answer 2

Yeast vs mould (description based on appearance)

Superficial vs deep (based on site of infection)

Question 3

What are dimorphic fungal infections?

Answer 3

Can exist as both mould and yeast form, often due to temperature. Therefore usually yeast during infection but mould at room temp (ie in lab)

“Mould in the Cold, Yeast in the Beast”

Question 4

Give 3 common sites of superficial fungal infection

Answer 4

Skin, hair, nails

Question 5

How are superficial fungal infections diagnosed?

Answer 5

Woods lamp (UVA/black light)

Question 6

Name two types of organism that cause superficial fungal infection.

Answer 6

Dermatophytes

Malassezia

Question 7

Which organisms cause tinea infections? Give a specific example

Answer 7

Dermatophytes, eg Tricophyton rubrum

Question 8

Which organisms cause fungal pityriasis infections? Give a specific example

Answer 8

Malassezia globosa/furfur

Question 9

Give 3 examples of tinea infection

Answer 9

Ringworm
Athlete’s foot
Jock itch

Question 10

Give 2 examples of fungal pityriasis infection

Answer 10

Seborrhoeic dermatitis

Pityriasis/Tinea versicolour

Question 11

Name 3 fungal infections that can become deep-seated, especially in the immunocompromised

Answer 11

Candida
Aspergillus
Cryptococcus

Question 12

How are deep candida infections diagnosed?

Answer 12

Culture
Mannan antigen test
(Mannan is a glycoprotein found in the cell walls of Candida albicans)
Antibody tests

Question 13

How do Aspergillus infections present?

Answer 13

Can be anywhere on spectrum from allerfy to invasion.

In immunocompromised presents as pneumonia. High mortality

Question 14

How is aspergillus diagnosed?

Answer 14

ELISA
PCR
Beta-glucan test

Question 15

How does cryptococcus infection present in the immunocompromised (particularly HIV)?

Answer 15

Meningitis with insidious onset

Question 16

How is cryptococcus diagnosed?

Answer 16

Cryptococcal antigen in serum/CSF

Question 17

List the 5 classes of antifungal

Answer 17

Polyene
Azole
Terbinafine
Flucytosine
Echinocandin

Question 18

Give an example of a polyene antfiungal

Answer 18

Amphotericin

Question 19

Give an example of an azole antifungal

Answer 19

Fluconazole

Question 20

Give an example of an echinocandin

Answer 20

Caspofungin

Question 21

Describe the target of polyene antifungals

Answer 21

Cell membrane integrity

Question 22

Describe the target of azole antifungals

Answer 22

Cell membrane synthesis

Question 23

Describe the target of terbinafine antifungals

Answer 23

Cell membrane permeability, leading to cell lysis

Question 24

Describe the target of flucytosine antifungals

Answer 24

DNA synthesis

Question 25

Describe the target of echinocandin antifungals

Answer 25

Cell wall

Question 26

Which classes of antifungals are indicated for yeast infections?

Answer 26

Polyenes, Azoles and Echinocandins

Question 27

What is an advantage of echinocandins?

Answer 27

Less toxic side effects than other anti-yeast antifungals

Question 28

Which class of antifungals is indicated for dermatophytic mould infections (tinea)?

Answer 28

Terbinafine

Question 29

What is the antifungal Amphotericin B used to treat? (specific infection)

Answer 29

Cryptococcal meningitis + invasive fungal infection