INFECTIOUS AGENTS - Mycology

Question 1

What is mycology?

Answer 1

Mycology is the study of fungus

Question 2

What are the three components of the fungi cell wall?

Answer 2

Chitins
Mannans
Glucans

Question 3

What is the main sterol found in the fungal plasma membrane?

Answer 3

Ergosterol

Question 4

What is the infectious form of fungi?

Answer 4

Fungal spores

Question 5

What are the three diagnostic methods that can be used to diagnose a fungal infection?

Answer 5

Direct microscopy
Culture
Histopathology

Question 6

What are the three main classifications of fungi?

Answer 6

Yeast
Filamentous
Dimorphic

Question 7

How do yeast reproduce?

Answer 7

Yeast undergo budding

Question 8

What is the term used to describe the structure formed when yeast daughter cells don’t detach from the original yeast?

Answer 8

Pseudohyphae

Question 9

(T/F) Yeast stain as Gram negative (G-)

Answer 9

FALSE. Yeast stain as Gram positive (G+)

Question 10

What are the three most important pathogenic yeast genera in veterinary medicine?

Answer 10

Candida
Malassezia
Cryptococcus

Question 11

What should be used to grow candida and malassezia in culture?

Answer 11

Candida and malassezia should be grown on Sabouraunds dextrose agar at 37°C

Question 12

Candida is polymorphic, what does this mean?

Answer 12

Candida has three forms - a yeast form, hyphae form and pseudohyphae form

Question 13

What is the pathogenic form of candida fungi?

Answer 13

Hyphae

Question 14

What is the name of the fungal spores produced by candida fungi?

Answer 14

Chlamydospores

Question 15

What is the most common pathogenic species of candida?

Answer 15

Candida albicans (C. albicans)

Question 16

What are the three diseases caused by candida albicans infection in cattle?

Answer 16

Mycotic abortion
Rumenitis
Mastitis

Question 17

What are the three diseases caused by candida albicans infection in dogs?

Answer 17

Dermatitis
Enteritis
Vaginitis

Question 18

Which test can be used to specifically test for Candida albicans?

Answer 18

Germ tube test

Question 19

Give an example of a species of malassezia

Answer 19

Malassezia pachydermatitis (M. pachydermititis)

Question 20

What are the two diseases caused by malassezia pachydermititis infection?

Answer 20

Dermatitis
Otitis externa

Question 21

How does malassezia pachydermititis cause skin irritation?

Answer 21

M. pachydermitis produces urease which breaks down into ammonia and irritates the skin

Question 22

What is the most common pathogenic species of cryptococcus?

Answer 22

Cryptococcus neoformans (C. neoformans)

Question 23

Cryptococcus is an opportunistic pathogen. Which specific immunocompromised individuals does cryptococcus target?

Answer 23

Individuals with a defective cell-mediated immunity

Question 24

Which disease is most commonly seen due to cryptococcus infection?

Answer 24

Rhinitis

Question 25

Which virulence factor allows cryptococcus to be one of the only fungi that can cause meningitis?

Answer 25

Anti-phagocytic mucilaginous capsule

Question 26

Which stain can be used to identify the mucilaginous capsule in culture?

Answer 26

India ink stain

Question 27

What is the structure of filamentous fungi?

Answer 27

Filamentous fungi have a primary hyphae structure which branches to form mycelium (mould)

Question 28

What are the two forms of filamentous mycelium?

Answer 28

Septate Non-septate

Question 29

What are the two most important pathogenic filamentous fungi categories in veterinary medicine?

Answer 29

Dermatophytes Aspergillus

Question 30

How should dermatophytes and aspergillus filamentous fungi be grown in culture?

Answer 30

Dermatophytes and aspergillus should be grown on Sabouraunds dextrose agar at 28°C

Question 31

What do dermatophytes digest and how does this relate to where on the body they cause infection?

Answer 31

Dermatophytes digest keratin and thus cause hair, skin and nail infections

Question 32

What is the name of the fungal spores produced by dermatophytes?

Answer 32

Arthrospores

Question 33

What are the two types of fungal spore that are only produced by dermatophytes during lab culture?

Answer 33

Microconidia Macroconidia

Question 34

List two genera of dermatophytes

Answer 34

Microsporum Trichophyton

Question 35

Which disease is caused by microsporum and trichophyton?

Answer 35

Ring worm

Question 36

How can a 'wood lamp' be used to identify a microsporum infection?

Answer 36

A 'wood lamp' produces ultraviolet (UV) light which causes fluorescence of microsporum lesions

Question 37

Which species of microsporum causes ringworm in dogs and cats?

Answer 37

Microsporum canis (M. canis)

Question 38

Which species of trichophyton causes ringworm in cattle?

Answer 38

Trichophyton verrucosum (T. verrucosum)

Question 39

How can trichophyton verrucosum be easily identified in culture?

Answer 39

T. verrucosum is the only dermatophyte which grows at 37°C in Sabouraunds dextrose agar

Question 40

What does aspergillus require in order to produce fungal spores?

Answer 40

Oxygen

Question 41

What is the name of the fungal spores produced by aspergillus?

Answer 41

Conidia

Question 42

What are the three diseases caused by aspergillus infection?

Answer 42

Pneumonia Nasal aspergillosis Mycotic abortion (in cattle)

Question 43

What is the most common pathogenic species of aspergillus?

Answer 43

Aspergillus fumigatus (A. fumigatus)

Question 44

Aspergillus conidia (spores) are in the air constantly. How does the immune system of healthy animals defend against these spores?

Answer 44

Aspergillus conidia and continually inhaled however macrophages phagocytose the conidia within the lungs. If any of the conidia get the chance to develop into hyphae, they will be phagocytosed by neutrophils

Question 45

What are mycotoxins?

Answer 45

Mycotoxins and naturally occurring toxins produced by fungi

Question 46

What is the carcinogenic mycotoxin produced by aspergillus fumigatus fungi?

Answer 46

Aflatoxin

Question 47

What is ergotism?

Answer 47

Ergotism is a condition caused by the ingestion of mycotoxin which affects the nerves innervating arteriolar smooth muscle

Question 48

What is mycotic oestrogenism?

Answer 48

Mycotic oestrogenism is a condition caused by mycotoxins which alter the oestrogen levels within the body