Introduction to Fungi Flashcards
classification of fungi
principally based on morphology. Three major types:
- Basidiomycetes (Mushrooms)
- Ascomycetes
- Zygomycetes (moulds)
Dermatophytosis
an infection of the skin caused by moulds with a predilection to degrade keratin as a nutrient source.
fungi that cause dermatophytosis (ringworm/tinea)
- epidermophyton (epidermophyton floccosum)
- microsporum (microsporum canis)
- trichophyton (trichophyton mentagrophytes)
pityriasis versicolor
caused by malassezia spp. causes discoloured blotches on skin.
what do Candida spp. infect?
infect deep organs of patients with various types of immune dysfunction.
which patients are susceptible to aspergillus spp. infections?
infect deep organs of patients undergoing treatments such as chemotherapy and stem cell transplantation
Candida infections (candidiasis, candidosis)
cause a wide range of infections: oral vaginal skin nail oesophageal urinary tract disseminated
candida species
candida:
albicans
tropicalis
glabrata
what type of fungi is candida?
yeast
aspergillus infections (aspergillosis)
- simple asthma
- asthma with eosinophilia (high levels of eosinophils)
- aspergilloma
- invasive bronchopulmonary aspergillosis
- disseminating aspergillosis
aspergillosis causing spp.
- aspergillus fumigatus
- aspergillus flavus
what type of fungi are aspergillus spp. ?
moulds
cryptococcus infections
- pulmonary cryptococcosis
- meningitis
- disseminated infection
In what type of patients do disseminated infections occur?
seriously immunocompromised patients
main causative species for cryptococcosis
- cryptococcus neoformans
- cryptococcus gattii
describe the properties of fungi
chemo-organotropic eukaryote that lacks chlorophyll and forms spores.
host factors that contribute to pathogenicity of fungi
- 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
diagnostic methods for identifying fungal infections
- 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
mechanisms of action for antifungal drugs
target:
- cell walls (echinocandins)
- cell membrane (polyenes)
- target DNA synthese (flucytosine)
- target sterols (triazoles and allylamines)
issues with antifungal agents
toxicity- drugs may be toxic to patient
resistance- fungus may develop resistance to drug
cost- treatments can be expensive
echinocandins action
target cell wall
polyenes action
target cell membrane
flucytosine action
target dna synthesis
triazoles and allylamine action
target-sterols
