Introduction to Fungi

Question 1

What can fungi infect?

Answer 1

• Plants
• Insects
• Amphibians
• Mammals

Question 2

What is mycology?

Answer 2

The study of fungi

Question 3

What is a fungi?

Answer 3

A chemo-organotropic eukaryote that lacks chlorophyll and forms spores. Its cell wall contains polysaccharides, often, chitin or glucan and it absorbs nutrients. Its membrane contains egosterol as the major sterol.

Question 4

What are the 3 groups of fungi?

Answer 4

• Basidiomycetes
• Ascomycetes
• Zygomycetes

Question 5

What are the sexual and asexual spores of each group?

Answer 5

Basidiomycetes
-S:basidiospores
-A:conidium
Ascomycetes
-S:ascospores
-A:conidium
Zygomycetes
-S:zygospore
-A:sporangiospores

Question 6

What are examples of ascomycetes?

Answer 6

• Candida

- Aspergillus spp

Question 7

What is an example o of a basidiomycete?

Answer 7

Crytococcus species

Question 8

What is an example of a zygomycete/

Answer 8

Rhizopus species

Question 9

What are yeasts?

Answer 9

Fungi that favour a unicellular habit

Question 10

What non-fatal diseases can fungi cause?

Answer 10

-Athletes foot: Epidermophyton, Microsporum and Trichophyton spp
-Thrush:Candida
Pityriasis veriscolor: Malssezia spp

Question 11

What are ringworm infections usually called?

Answer 11

Tinea…

Question 12

What is dermatophytosis caused by?

Answer 12

Moulds with a dredilection to degrade keratin as a nutrient source

Question 13

What are the causative agents of dermatophytosis?

Answer 13

• Epidermophyton
• Microsporum
• Trichophyton spp

Question 14

What is the causative agent of pityriasis veriscolor?

Answer 14

Malassezia spp

Question 15

What is pityriasis veriscolor caused by?

Answer 15

Yeasts that also form hyphae in infected skin

Question 16

What group of immunocompromised individuals does Candida species affect?

Answer 16

Infect deep organs of patients with various types of immune dysfunction e.g. after abdominal surgery, burns

Question 17

What group of immunocrompromised individuals does Aspergillus species affect?

Answer 17

Infect deep organs of patients undergoing chemotherapy and stem cell transplantation

Question 18

What factors contribute to pathogenicity of fungal infections?

Answer 18

• Favourable micro-environments
• Broad-spectrum antibacterial agents reduce competition for epithelial colonisation sites in gut
• Immunosuppression

Question 19

What are examples of iatrogenic immunosuppression of host defenced?

Answer 19

• Steroids
• Anti-cancer chemotherapy
• Solid-organ transplantation

Question 20

What are examples of disease process that can immunosuppress host defenced?

Answer 20

• AIDS
• Leukaemia
• Endocrinopathies

Question 21

Describe candida specie.

Answer 21

• Commensal to GI tract
• Most infections are enogenous
• Candida spp are yeasts
• C.albicans can form hyphae

Question 22

What infections can Candida spp cause?

Answer 22

• Superficial of mouth, vagina, penis, skin, nails

- Deep-seated: disseminated infections in seriously immunocompromised hosts

Question 23

How can chronic mucocutaneous Candida infections arise?

Answer 23

In individuals with an unusual combination of endocrine and immune dysfunction

Question 24

Describe aspergillus spp.

Answer 24

• Moulds
• Ubiquitous in the environment: infection occurs by spore inhalation
• strongly angioinvasive

Question 25

What is invasive pulmonary aspergillosis mainly associated with?

Answer 25

Haemotological malignancy

Question 26

What diagnostic methods are used in mycology?

Answer 26

• Direct detection (histopathology, CT)
• Detection of circulating fungal antigens
• Detection circulating antibodies to fungi
• PCR for fungal DNA
• Culture of fungus from normally sterile site