Mycology

Question 1

What are fungi?

Answer 1

eukaryotic cells that are plant like but lack chlorophyll

Question 2

What is yeast?

Answer 2

unicellular fungi

Question 3

How do yeast breathe?

Answer 3

facultative anaerobe

Question 4

How do yeast reproduce?

Answer 4

asexually by budding

Question 5

What is mould?

Answer 5

filamentous fungi

Question 6

How does mould breathe?

Answer 6

aerobic

Question 7

How does mould reproduce?

Answer 7

asexually by spores (conidia)

Question 8

What is dimorphic fungi?

Answer 8

fungi that can live either as yeast or mould

Question 9

What does yeast look like on a gram stain?

Answer 9

like gram positive cocci - but bigger and can sometimes see them budding

Question 10

What does yeast look like on agar?

Answer 10

like bacteria - small grey colonies - but can smell the yeast

Question 11

What are dermatophytes?

Answer 11

the fungi which cause ring worm - grow on the skin but dont invade deeply

Question 12

What is cave’s disease?

Answer 12

histoplasmosis caused by the dimorphic fungi histoplasma capsulatum

Question 13

Why are dimorphic fungi particularly virulent?

Answer 13

because they can grow as the filamentous form in the environment and then as the yeast form to infect

Question 14

What is subcutaneous mycoses?

Answer 14

a fungal infection where the pathogen is implanted or introduced to the dermis

Question 15

How do aspergillus cause cancer?

Answer 15

by producing the carcinogenic aflatoxin

Question 16

What do dermatophytes cause?

Answer 16

tinea

Question 17

What do dermatophytes eat?

Answer 17

keratin

Question 18

How do dermatophytes cause a skin reaction?

Answer 18

by producing metabolites which are irritating

Question 19

What is tinea corporis?

Answer 19

ring worm

Question 20

What is tinea pedis?

Answer 20

atheletes foot

Question 21

What is mycetoma?

Answer 21

madura foot - a disease which almost always affects the foot and looks like a tumour - can be caused by either a bacteria (nocardia) or a fungi (madurella)

Question 22

What is mucocutaneous candidiasis?

Answer 22

an opportunistic mycoses caused by candida albicans infecting mucous membranes

Question 23

What is chronic mucocutaneous candidiasis?

Answer 23

a candidiasis in people with immune defects where there is chronic infection of the mucous membranes

Question 24

What is systemic candidiasis?

Answer 24

where candida albicans invades and causes septicaemia which is fatal

Question 25

Why are patients more at risk of vaginal thrush after taking antibiotics?

Answer 25

because the lactobacilli in the vagina keep the pH low and when they are killed off by the antibiotics it creates an environment where the fungi can grow

Question 26

What are the two agents that cause cryptococcosis?

Answer 26

c. neoformans and c. gattii

Question 27

What is cryptococcosis?

Answer 27

initially a mild pulmonary infection but if it spreads through the blood it will cause fungal meningitis

Question 28

What is saprophytic aspergillosis?

Answer 28

where aspergillus grows inside a pre existing cavity e.g. in cavitating TB - mostly asymptomatic or a few minor pulmonary symptoms - looks like a tumour on an xray

Question 29

What is allergic aspergillosis?

Answer 29

allergic manifestations to aspergillosis - can present as lesions in the hand

Question 30

What is systemic aspergillosis?

Answer 30

classic in immunocompromised patients - disseminates throughout the body and can infect many different organs

Question 31

How do you diagnose fungal infections?

Answer 31

microscopy, culture, antigen detection, PCR, mass spec

Question 32

What are some systemic anti fungals?

Answer 32

polyenes, triazoles, echinocandins, 5-flurocytosine

Question 33

What are some topical anti fungals?

Answer 33

polyenes, imidazoles

Question 34

What is the mechanism of action of polyenes?

Answer 34

affects the integrity of ergosterol in the cytoplasmic membrane

Question 35

What is the mechanism of action of 5-flurocytosine?

Answer 35

affects DNA and RNA synthesis

Question 36

What is amphotericin B?

Answer 36

a polyene