Introduction to Fungi

Question 1

What does the cell wall of a fungus contain?

Answer 1

Polysaccharides, often chitin or cellulose.

Question 2

Does a fungi form spores?

Answer 2

Yes

Question 3

Does a fungi contain chlorophyl?

Answer 3

No

Question 4

What is the informal classification of fungi?

Answer 4

moulds, yeasts or mushrooms

Question 5

What is the cell type of a fungi?

Answer 5

They favour a unicellular habitat

Question 6

What kind of infections are by dermatophytes?

Answer 6

ringworm and related diseases

Question 7

What is the prefix for a ringworm infection?

Answer 7

tinea

Question 8

What is the action of dermatophytes on keratin?

Answer 8

Moulds with a predilection(liking) to degrade keratin as a nutrient source.

Question 9

What does a pityriasis versicolor cause on the skin?

Answer 9

Forms hyphae in infected skin

Question 10

What do candida species infect?

Answer 10

Deep organs of patients with various types of immune dysfunction

Question 11

What do aspergillus spp infect?

Answer 11

Infects deep organs of patients undergoing e.g chemotherapy, stem cell transplantation

Question 12

What is a favourable micro-environment that will contribute to pathogenicity of a fungal infection?

Answer 12

Warm moist areas - encourages the growth of fungi on skin and mucous membranes. Broad spectrum antibacterial agents reduce competition for epithelial colonization sites in the gut. Immunosuppression of all types may create a window of opportunity for fungal invasion

Question 13

Describe the immunosuppression of host defences

Answer 13

Disease processes - Aids Leukaemia

Anti-cancer chemotherapy

Iatrogenic (caused by medical examination or treatment)

Steroids

Endocrinopathies

Solid organ transplantation

Question 14

Where are candida species commensal to?

Answer 14

The GI tract

Question 15

What are risk factors for candidiasis?

Answer 15

Age, antibiotic therapy, endocrine disorders, immune defects, immune suppression, surgery

Question 16

What are the diseases possible as a result of candida?

Answer 16

Vaginal infections

Skin infections

Nail infections

Oral infections

Oesophageal infections

Disseminated infections - in seriously immunocompromised patients

Question 17

What is hyphae?

Answer 17

The fine branching tubes which make up the body (mycelium) of a multicellular fungus

Question 18

Give examples of superficial candida infections

Answer 18

Mouth, vagina, penis, skin, nails

Question 19

Give examples of a seriously immunocompromised host

Answer 19

Suffering from neutropenia, abdominal surgery, major burns

Question 20

Give examples of human diseases caused by Aspergillosis

Answer 20

Simple asthma Asthma with eosinophilia

Aspergilloma

Invasive bronchopulmonary aspergillosis

Disseminated aspergillosis.

Question 21

How does infection by aspergillus spp occur?

Answer 21

They are moulds ubiquitous in the enviroment - infection occurs by inhalation of conidia
(Ubiquitous- found everywhere)

Question 22

Define conidium

Answer 22

A spore produced asexually by various fungi at the tip of a specialised hypha

Question 23

Aspergillus is said to be angioinvasive, what does this mean?

Answer 23

Penetrates the walls of the blood vessels.

Question 24

What is the causative species for cryptococcosis?

Answer 24

Cryptocuccus…… neoformans/gattii

Question 25

What are the main diseases caused by cryptococcosis?

Answer 25

Pulmonary cryptococcosis

Meningitis (prevalent in AIDS patients)

Question 26

What are the diagnostic methods for fungal infections?

Answer 26

Direct detection - histopathology (including direct smears and growth on selective medium) also the use of High resolution CT scans Detection of fungal antigens as well as antibodies to fungi

PCR for fungal DNA Culture of fungus from normally sterile site

Question 27

What are the technical names for the three types of fungi?

Answer 27

Basidiomycetes (mushrooms) (cryptococcus)

Ascomycetes (candida, Aspergillus)

Zygomycetes (bread mould)