015 Medical Mycology: Fungi and Fungal disease

Question 1

What is superficial Candida infection? Symptoms?

Answer 1

Yeast infection that normally breaks through irritated epithelial barriers in moist environments. It can cause oral thrush, vaginal infections and nappy rashes. It occurs to 75% of women.

Question 2

When may candida undergo hyphal switch? How may this occur when someone is taking antibiotics?

Answer 2

During environmental changes such as increase in pH >7, serum presence, temperature changes, starvation. This can occur to someone taking B lactam antibiotics because they will have killed the Lactobacilli in the vagina. This raises the pH in the vagina, which stimulates the Candida yeast to switch to hyphae mode.

Question 3

Where do superficial dermatophyte infections occur?

Answer 3

On keritinized tissues e.g nails, hair, skin. They land on these surfaces, lay down adhesin and secrete keratinase and assimilate oligopeptides/amino acids.

Question 4

What are the 2 most common infections that occur in the immunocompetent?

Answer 4

Superficial Dermatophyte infections

Superficial Candida infections

Question 5

Which is the most common organism causing superficial dermatophte infections? What does it cause?

Answer 5

Tychophyton rubrum (95%), causing ring worms. The spores lands in the central and start to grow outwards in mycelial network. the growing edge in the lesion becomes hyperinflammed.

Question 6

Which is the interleukin responsible for the recruitment of neutrophils?

Answer 6

IL8

Question 7

What are 3 common dimorphic fungi?

Answer 7

Histoplasma capsulatum
Blastomycosis
Coccidiodes immitis

Question 8

What occurs in Blastomycosis infections?

Answer 8

Spores are inhaled; during phagocytosis by macrophages, the yeast at 36 degrees will replicate burst out of the cell.

Question 9

What occurs in Coccidiodes immitis infections?

Answer 9

Spores are inhaled and inside the lungs it grows into hyphae which invade and replication in the lung tissue.

Question 10

What occurs in Histoplasma capsulatum infections?

Answer 10

Spores are inhaled and during phagocytosis by neutrophils, it will replicate causing cell lysis.

Question 11

Where do dimorphic fungi infections normally prevail?

Answer 11

In the US due to antimicrobial use. Not really in the UK

Question 12

What is dimorphic fungi?

Answer 12

Fungi that can switch between the yeast and mould modes depending on environment.

Question 13

If a bacteria has more mannan in its cell wall, what occurs to the body?

Answer 13

More inflammation occurs

Question 14

What is the mortality rate of invasive aspergillosis and candida albicans?

Answer 14

40-50%

Question 15

What is the main cause of invasive Candida albicans?

Answer 15

Use of antimicrobial antibiotics which disrupts gut microbiome
Immunosuppression

Question 16

How may you diagnose invasive Candida albicans?

Answer 16

Blood culture of CT (nonspecific)

Question 17

How do you diagnose invasive pulmonary aspergillosis?

Answer 17

Testing for galactomannan markers in the blood
Radiology of lung showing halo presence with hazy edge. Cannot use blood tests directly because it is located in the lung tissue.

Question 18

Why are patients with bone marrow transplants more susceptible to pulmonary aspergillosis?

Answer 18

Neutropenia: neutrophils have antihyphal activity by surrounding conidia in airways and preventing its germination without acquiring uptake

Question 19

When would mucoraceous mould infections most likely occur?

Answer 19

To diabetic patients with high iron levels

Question 20

Name two AIDs defining invasive fungi diseases

Answer 20

Cryptococcus causing meningitis
Pneumocytis pneumonia
Both are yeast like infections

Question 21

What type of fungi is Crytococcus neoformans?

Answer 21

Yeast like

Question 22

Where are Saprophytes found?

Answer 22

On dead organisms

Question 23

Describe the reproduction process of fungi? What is mycelial fragmentation?

Answer 23

Spores will develop into hyphae. Networks of hyphae will form mycelium. Mycelial fragmentation occurs when parts of mycelial network split off and form their own networks.

Question 24

What is a very severe indication of invasive Candida albicans associated with very high mortality rate?

Answer 24

Candida opthalmitis in the eye