fungal infections

Question 1

what are fungi?

Answer 1

Eukaryotic
Chitinous cell wall
Heterotrophic

Question 2

how do fungi move?

Answer 2

Move by means of growth or through the generation of spores, which are carried through air or water

Question 3

describe yeasts

Answer 3

Yeasts are small single celled organisms that divide by budding
Account for <1% of fungal species but include several highly medically relevant ones

Question 4

what do moulds form?

Answer 4

Moulds form multicellular hyphae and spores

Question 5

what are dimorphic fungi?

Answer 5

Some fungi exist as both yeasts and moulds switching between the two when conditions suit

Question 6

how is it that only a few hundred species can cause human infection?

Answer 6

Inability to grow at 37 degrees
Innate and adaptive immune response

Question 7

what does the eukaryotic feature of fungi limit?

Answer 7

limits options for selective toxicity

Question 8

what is fungi cell wall made up of?

Answer 8

mannoproteins
Β1,3 glucan
Β1,6 glucan
chitin
Doesn’t exist in humans

Question 9

what does the plasma membrane of fungi made up of?

Answer 9

ergosterol

Question 10

what drugs affect the fungi cell wall?

Answer 10

Echinocandins

Question 11

what drugs affect the fungi plasma membrane?

Answer 11

ergosterol
Polyenes e.g. amphotericin
Azoles
Allylamines e.g. terbinafine

Question 12

what drugs affect DNA/rna synthesis?

Answer 12

Flucytosine
Griseofulvin

Question 13

which fungal infections are very common?

Answer 13

superficial fungal infection

Question 14

which fungal infections are very rare?

Answer 14

Invasive fungal infection

Question 15

what is the aim of antimicrobial drug therapy?

Answer 15

to achieve inhibitory levels of agent at the site of infection without host cell toxicity

Question 16

what does antimcrobial drug therapy rely on?

Answer 16

Relies upon identifying molecules with selective toxicity for organism targets
Target does not exist in humans
Target is significantly different to human analogue
Drug is concentrated in organism cell with respect to humans
Increased permeability to compound
Modification of compound in organism or human cellular environment
Human cells are ‘rescued’ from toxicity by alternative metabolic pathways

Question 17

what are risk factors for mucosal commensal

Answer 17

immunosuppression, diabetes antibacterial therapy and mucosal disruption

Question 18

what is used to treat mucosal candidiasis?

Answer 18

Treatment with topical or oral azoles

Question 19

what is common in recurrant cases?

Answer 19

Resistant disease common in recurrent cases
Acquired resistance in normally susceptible species
Selection for intrinsically resistant species

Question 20

how can dermatophytes spread?

Answer 20

human-human
animal-human

Question 21

how are dermatophytes treated?

Answer 21

Treatment is usually with topical or oral azoles or terbinafine

Question 22

is ringworm a worm

Answer 22

NO

Question 23

What does tines capitis look like?

Answer 23

plucked hair
scalp scraping

Question 24

what does tinea corporis look like?

Answer 24

Scraping of scaled edge of lesion

Question 25

how do dimorphic fungi infect

Answer 25

via inhalation of conidia from soil or implantation

Question 26

when do dimorphic fungi develop mould?

Answer 26

at ambient temperature (25-30OC)

Question 27

when do dimorphic fungi convert to yeast form?

Answer 27

37OC
Occurs in response to heat related stress on organism

Question 28

what does fungal diagnosis rely on?

Answer 28

it being differential

Question 29

what are the differential diagnosis of sub-acute/chronic meningitis- infective

Answer 29

Tuberculosis
Cryptococcus
Dimorphic fungi – Histoplasma, Coccidioides, Blastomyces
Lyme
Brucella
Syphilis

Question 30

what are the differential diagnosis of sub-acute/chronic meningitis-non- infective

Answer 30

Sarcoidosis
Behçets’s
SLE
Malignant
Drug induced