Introduction to Fungi

Question 1

classification of fungi

Answer 1

principally based on morphology. Three major types:

• Basidiomycetes (Mushrooms)
• Ascomycetes
• Zygomycetes (moulds)

Question 2

Dermatophytosis

Answer 2

an infection of the skin caused by moulds with a predilection to degrade keratin as a nutrient source.

Question 3

fungi that cause dermatophytosis (ringworm/tinea)

Answer 3

• epidermophyton (epidermophyton floccosum)
• microsporum (microsporum canis)
• trichophyton (trichophyton mentagrophytes)

Question 4

pityriasis versicolor

Answer 4

caused by malassezia spp. causes discoloured blotches on skin.

Question 5

what do Candida spp. infect?

Answer 5

infect deep organs of patients with various types of immune dysfunction.

Question 6

which patients are susceptible to aspergillus spp. infections?

Answer 6

infect deep organs of patients undergoing treatments such as chemotherapy and stem cell transplantation

Question 7

Candida infections (candidiasis, candidosis)

Answer 7

cause a wide range of infections:
oral 
vaginal
skin
nail
oesophageal
urinary tract
disseminated

Question 8

candida species

Answer 8

candida:
albicans
tropicalis
glabrata

Question 9

what type of fungi is candida?

Answer 9

yeast

Question 10

aspergillus infections (aspergillosis)

Answer 10

• simple asthma
• asthma with eosinophilia (high levels of eosinophils)
• aspergilloma
• invasive bronchopulmonary aspergillosis
• disseminating aspergillosis

Question 11

aspergillosis causing spp.

Answer 11

• aspergillus fumigatus

- aspergillus flavus

Question 12

what type of fungi are aspergillus spp. ?

Answer 12

moulds

Question 13

cryptococcus infections

Answer 13

• pulmonary cryptococcosis
• meningitis
• disseminated infection

Question 14

In what type of patients do disseminated infections occur?

Answer 14

seriously immunocompromised patients

Question 15

main causative species for cryptococcosis

Answer 15

• cryptococcus neoformans

- cryptococcus gattii

Question 16

describe the properties of fungi

Answer 16

chemo-organotropic eukaryote that lacks chlorophyll and forms spores.

Question 17

host factors that contribute to pathogenicity of fungi

Answer 17

• favourable micro-environments encourage growth of fungi on skin and mucous membranes
• broad spectrum antibacterial agents reduce competition for epithelial colonization sires in gut
• immunosuppression of all types may create a window of opportunity for fungal invasion

Question 18

diagnostic methods for identifying fungal infections

Answer 18

• direct detection (histopathology, high-res CT scans
• detection of circulating fungal antigens
• detection of circulating antibodies to fungi
• PCR for fungal DNA
• culture of fungi form normally sterile sites

Question 19

mechanisms of action for antifungal drugs

Answer 19

target:

• cell walls (echinocandins)
• cell membrane (polyenes)
• target DNA synthese (flucytosine)
• target sterols (triazoles and allylamines)

Question 20

issues with antifungal agents

Answer 20

toxicity- drugs may be toxic to patient
resistance- fungus may develop resistance to drug
cost- treatments can be expensive

Question 21

echinocandins action

Answer 21

target cell wall

Question 22

polyenes action

Answer 22

target cell membrane

Question 23

flucytosine action

Answer 23

target dna synthesis

Question 24

triazoles and allylamine action

Answer 24

target-sterols