Fungi Flashcards
What is a fungus and its structure?
A chemo-organotropic eukaryote that lacks chlorophyll and forms spores.
Its cell wall contains polysaccharides, often chitin or glucan and it absorbs nutrients.
Its membrane contains ergosterol as the major sterol.
What are the Major types of fungi?
moulds, yeasts or mushrooms
what is yeast?
fungi that favour a unicellular habit.
e.g. candida spp.
What are the three groups of fungi in the fungal kingdom?
Basidiomycetes
Ascomycetes
Zygomycetes
Outline example of Basidiomycetes.
Cryptococcus species.
Example= mushrooms
Outline example and structure of Ascomycetes.
Candida, Aspergillus spp.
Example= neurospora, saccharomyces
Outline example and structure of Zygomycetes.
Rhizopus species
Example= bread moulds
What are the types of fungi on our skin?
- Cyptococcus neoformans,
- candida albicans
- aspergillus fumigatus,
- superficial mycoses i.e. dermatophytosis, onchomycosis.
What are fungi a significant cause of and what are the dermatophytosis causative agents?
Non-fatal diseases i.e.
- Athlete’s foot caused by dermatophytosis causative agents Epidermophyton, Microsporum and Trichophyton spp.
- Thrush caused by Candida spp.
What are fungi increasingingly responsible for?
Fungi are increasingly responsible for fatal diseases.
- Candida species which infect deep organs of patients with various types of immune dysfunction e.g. after abdominal surgery, burns.
- Aspergillus sp. which infect deep organ of patients undergoing chemotherapy or stem cell transplantation.
What diseases are caused by the dermatophytes?
They cause “ringworm” infections, usually called tinea.
- Capitis
- Facei
- Barbae
- Corporis
- Cruris
What is a specific example of a fungal skin infection?
Pityriasis versicolor caused by yeast Malassezia spp. Malassezia spp. that form hyphae in infected skin.
Describe the host factors which contribute to pathogenicity of fungal infections.
- warm, moist areas which encourage the growth of fungi on skin and mucous membranes.
- Broad spectrum antibacterial agents which reduce competition for epithelial colonization sites in the gut
- Immunosuppression of host defences caused by:
- Latrogenic i.e. steroids, anti-cancer chemotherapy
- Disease processes i.e. AIDS, leukaemia
- Combinations of both
Outline the main causative species of Candida infections and the human diseases they cause.
Candida infections include candidiasis and candidosis.
Superficial:
- Candida albicans- causes oral infections. Candida albicans can also form hyphae (pleomorphism)
- Candida tropicalis- causes vaginal infections.
- Can cause penis, skin, nails diseases too.
Deep-seated:
- Disseminated infections in seriously immunocompromised hosts, can cause neutropenia, abdominal surgery and major burns.
Chronic mucocutaneous Candida infection…
Can arise in individuals with an unusually combination of endocrine and immune dysfunction.
