Fungal infections

Question 1

Bacteria:

Answer 1

• unicellular
• prokaryote
• circular chromosomes
• no membrane bound organelles
• 70s ribosomes
• asexual reproduction
• peptidoglycan cell wall

Question 2

Fungi:

Answer 2

• can be multicellular
• eukaryote
• distinct nucleus
• DNA on several chromosomes
• membrane-bound organelles
• 80s ribisomes
• sexual or asexual reproduction
• chitin cell wall

Question 3

How many known species of fungi are there?

Answer 3

250,000

Question 4

Saprophytes =

Answer 4

organisms that live in the environment

Question 5

Why are fungi infections so rare?

Answer 5

• Not well adapted to 37 degrees, redox poTentials, human nutirents
• host defence mechanisms
• slow growing
• already highly successful in environment

Question 6

Fungal infections are most common in:

Answer 6

Immunocompromised

Question 7

Ex of immunocompromised patients:

Answer 7

• HIV
• Chemotherapy
• Diabetes mellitus
• Pregnancy
• Leukemia, lymphoma
• Steroids

Question 8

Fungal infections in the immunocompromised may..

Answer 8

• more common
• disseminate
• more severe
• be a type that doesn’t occur in immunocompetent

Question 9

3 types of fungi:

Answer 9

1. moulds
2. yeasts
3. dimorphic

Question 10

Moulds:

Answer 10

Grow by formation of filaments (hyphae) which form mycelium

Question 11

In moulds, what is visible to the naked eye?

Answer 11

Mycelium

Question 12

Reproduction of moulds:

Answer 12

• sexual

- asexual

Question 13

Ex of moulds:

Answer 13

Apergillus

Question 14

Yeasts:

Answer 14

Single-celled organisms, round.

Question 15

Reproduction of yeasts:

Answer 15

Budding, asexual

Question 16

ex of pathogenic yeasts:

Answer 16

Candida species

Cryptococcus neoformans

Question 17

Candida albicans has:

Answer 17

Pseudohyphae and true hyphae

Question 18

Dimorphic fungi:

Answer 18

Can grow as yeasts or mould. Yeast = infection, Mould = saprophytic

Question 19

Ex of dimorphic fungi:

Answer 19

Coccidiodes immitis (coccidiodomycoses)

Question 20

Toxic substance produced by fungus:

Answer 20

Mycotoxins

Question 21

Mycotoxins can cause conditions such as:

Answer 21

Ergotism

Question 22

Ex of hypersensitivity to fungi:

Answer 22

Asthma, farmer’s lung

Question 23

2 kinds of superficial mycoses:

Answer 23

1. no tissue invaded, no cellular response

2. no tissue invaded, cellular response

Question 24

Ex no tissue invaded, no cellular response:

Answer 24

Tinea versicolour = painless scaling of skin

Question 25

Tinea versicolor is caused by:

Answer 25

Yeast Malasezzia furfur

Question 26

Malasezzia furfur:

Answer 26

- yeasts | - feeds on keratin but doesn't produce host immune response

Question 27

Ex No tissue invaded but host response elicited:

Answer 27

Ringworm/tinea/dermatophytosis.

Question 28

Ringworm =

Answer 28

Use keratin as a nutrient (via production of keratinase). Ellicits a host response

Question 29

3 groups of ringworms:

Answer 29

1. geophillic 2. zoophillic 3. anthropophillic

Question 30

Athletes foot =

Answer 30

tinea pedis

Question 31

Ringworm vs eczema:

Answer 31

Ringworm: doesn't itch as much, anywhere, circular ring with raised borers and clear center Eczema: itches, elbows and behind knees, flat borders.

Question 32

Subcutaneous mycoses are a result of:

Answer 32

Direct penetration of fungus into dermis and subcutaneous tissue through traumatic injury

Question 33

Most common deep/systemic mycoses:

Answer 33

Aspergillus fumigatus.

Question 34

Aspergillus fumigatus:

Answer 34

Deep infection followed by inhalation of spores resulting in pulmonary aspergillosis. Can form a aspergilloma Can invade blood vessels and cause pulmonary haemorrhage or infarction

Question 35

Excepting to 'fungi grow slow' rule:

Answer 35

Murcomycoses

Question 36

Murcomycoses:

Answer 36

- start in sinuses - fast growing - don't respond to anti-fungals

Question 37

Ex of invasive yeast:

Answer 37

Candida

Question 38

Deep Candida:

Answer 38

Oesophagitis, candidaemia, endocarditis, hepatosplenic candidiasis

Question 39

Superficial candida:

Answer 39

Trush (mucus), cadiosis of skin (rash)

Question 40

Most common cause of thrush:

Answer 40

Candida albicans

Question 41

Coccidiodomycoses

Answer 41

Deep dimorphic mycoses. Respiratory symptoms, rash, fibrosis.

Question 42

How many classes of antifungals are there?

Answer 42

3

Question 43

Polyene =

Answer 43

Amphotericin

Question 44

Amphotericin B =

Answer 44

Binds to ergosterol

Question 45

Very broad spectrum anti-fungal =

Answer 45

Amphotericin B

Question 46

The most toxic drug used to treat infection =

Answer 46

Amphotericin B

Question 47

Toxicity of amphotericin:

Answer 47

- Renal damage | - Chills/fever during infusion

Question 48

Ex of Azoles

Answer 48

Flycoazole, voriconazole

Question 49

MoA of azoles

Answer 49

Inhibit enzyme lansosterol 14 a-demethylase.

Question 50

Lansosterol 14 a-demthylase:

Answer 50

converts lanosterol to ergosterol

Question 51

Ergosterol =

Answer 51

Fungi cholesterol

Question 52

Ex of exhinocandins:

Answer 52

Caspofugin

Question 53

MoA of echinocandins:

Answer 53

Inhibits glucan synthase so inhibits cell wall synthesis

Question 54

Use of echinocandins:

Answer 54

Invasive aspergillosis, invasive candida