Micro-organisms: Fungi Flashcards
What are the characteristics of fungi?
Eukaryotic Multicellular Chitin in cell wall Distinct nucleus 80s ribosomes Membrane bound organelles Reproduction is sexual or asexual
Between bacteria and fungi, which organism has cells more similar to a human cell?
Fungi
What type of fungus makes up the majority?
Saprophytes
What is the difference between fungi and other pathogens?
Fungi are not primary pathogens of humans; their main survival technique is not through harming us
When do saprophytic fungi come to being accidental pathogens?
In vulnerable/ immunocompromised patients
Why are fungal infections so rare?
Efficient immune response to them
Highly successful outside humans
Grow best via redox in non living substrates
Slow growing
Not adapted to growth:
- At our body temperature
- With our nutrients
What are the types of fungi?
Moulds
Yeast
Dimorphic
What are dimorphic fungi?
Shapeshifters between moulds and yeast
What type of fungus is most pathogenic?
Yeast
What are hyphae?
Long elongated cell, dividing with the appearance of plant roots.
These filaments aid mould growth.
What isa mycelium?
An entangled mass of hyphae which is visible to the naked eye.
What moulds cause human infection?
Aspergillius
What yeasts cause human infection?
Candida
Cryptococcus neoformans
What is the formation of true hyphae used as a diagnostic test for?
Candida albicans
What are pseudohyphae?
Elongated buds present when yeasts cause invasive disease
What are the characteristics of dimorphic fungi?
Grow as yeasts or moulds Yeast form causes infection Mould form is saprophytic Usually endemic Hard to spell
What is the mildest thing a fungus can do?
Live on our surfaces
What is Malasezzia furfur’s mechanism of action?
lives on the keratin of the skin (and other organic materials), feeds on keratin, brown in colour; causes a rash because of the colour
What is the problem with M. furfur?
Skin appearance similar to eczema
What are dermatophytoses?
Ringworm/ tinea; infection on stratum corner.
Lack of tissue invasion, eliciting of host response via fungal presence/ metabolites.
What are the three groups of dermatophytoses?
Geophilic- contact with soil
Zoophilic- contact with animals
Anthrophilic- contact with humans
With regards to itching, how do you differentiate between ringworm or eczema?
Ringworm doesn’t itch much
What is the angiotropic consequence of systemic mycoses?
Invasion of blood vessels -> pulmonary haemorrhage/ infarction
What is aspergilloma?
Colonisation of a pre-existing lung cavity
