Pathogens (Fritz Lecture 3 - A. fumigatus)

Question 1

What is Aspergillus fumigatus and where is it mainly found?

Answer 1

• It is a mould (also a fungus)

- Found in almost every environmental setting, but particularly in soil and decaying organic matter

Question 2

How does A. fumigatus infection occur?

Answer 2

Inhalation of spores called conidia

Question 3

Where does A. fumigatus mainly infect?

Answer 3

Mainly the lungs

Can disseminate and lead to secondary infection of other tissues

Question 4

What is a thermophile?

Answer 4

A type of extremophile

- can withstand high temperatures

Question 5

At what temperature can A. fumigatis grow and at what temp can it survive?

Answer 5

Growth can occur up to 50oC

Conidia can survive at 70oC

Question 6

What is the structure of A. fumigatus?

Answer 6

Filamentous fungi

• long stalk
• end of stalk has a vesicle
• budding from vesicles are phialides
• budding from phialides are conidia
• looks like a dandelion
• google picture for clarification

Question 7

What are the 3 main conditions associated with A. fumigatus?

Answer 7

1) Allergic Bronchopulmonary Aspergillosis (ABPA)
2) Aspergilloma (fungus ball)
3) Invasive Aspergillosis

Question 8

What is allergic bronchopulmonary aspergillosis (ABPA) and who is most commonly affected?

Answer 8

• Hyper-sensitivity reaction to A. fumigatus
• Large scale immune response and inflammation can cause lung damage
• Most common in individuals with asthma or cystic fibrosis

Question 9

What is an Aspergilloma? Who is most likely to get an aspergilloma?

Answer 9

• An aspergilloma is a clump of A.fumigatus (fungus ball) that grows in a cavity of the lungs
• Cavity most commonly caused by previous condition such as tuberculosis or cystic fibrosis

Question 10

What occurs in invasive aspergillosis?

Answer 10

A. fumigatus crosses the alveolar epithelium and disseminates via the blood to the brain, heart, eyes and/or kidneys

Question 11

Who is most commonly effected by invasive aspergillosis?

Answer 11

Immunocompromised individuals such as:

• people who have received a bone marrow or organ transplant
• People who have had high dose chemo for leukemia
• People with AIDS

Question 12

How is ABPA treated?

Answer 12

• Steroid medication to dampen immune response

- Antifungal medication to kill infection

Question 13

How is invasive aspergillosis treated?

Answer 13

In hospital with powerful antifungal medication given via a drip into a vein

Question 14

How are aspergillus infections diagnosed?

Answer 14

• X rays
• Detection of aspergillus IgG antibodies
• Detection of cell wall components (beta-1,3-glucans)

Question 15

What combination of methods are used in early diagnosis of invasive aspergillosis?

Answer 15

1) Radiology
2) Galactomannan assay (test for cell wall glucans)
3) Nucleic acid detection

Question 16

What are the virulence factors of A. fumigatus?

Answer 16

• Size of conidia
• Pigmentation of the conidia
• Hydrolytic enzymes

Question 17

What pigment does aspergillus produce and how does it work as a virulence factor?

Answer 17

Melanin

- reduces damage from host ROS