Introduction to Fungi. Flashcards
What types of life can fungi infect?
Plants, insects, amphibians and mammals
What is a fungus?
A chemo-organotrophic eukaryote that lacks chlorophyll and forms spores.
Describe the cell wall of a fungus.
Its cell wall contains polysaccharides, often chitin or glucan, and it absorbs nutrients.
What is the major sterol of the cell membrane of a fungues?
Ergosterol
What is classification of a fungi based on?
Their morphology.
Informally, what do we refer to as the three main types of fungi?
Mould, yeast or mushrooms.
Name the three major types of fungi.
Basidiomycetes, Ascomycetes and Zygomycetes.
How are Basidiomycetes, Ascomycetes and Zygomycete calssifed?
Depending on which sexual spore they produce.
What can all three of Basidiomycetes, Ascomycetes and Zygomycetes cause?
Disease in humans
Name one type of Zygomycetes.
Mucor Rhizopus
Name one type of Basidiomytes.
Cryptococcus
Name one type of Ascomycetes.
Candida Histoplasma
Name two non-fatal diseases caused by fungi.
Athlete’s foot
Thrush
Which species caused Athlete’s Foot?
Epidermophyton, Microsporum and Trichophyton spp.
Which species causes thrush?
Candida spp.
What is the main dermatophyte virulence factor of fungi?
Enzyme(s) that degrade and utilize keratin as a nutrient source
What is Dermatophytosis?
Ringworm
What causes Dermatophytosis
?
Epidermophyton
Microsporum
Trichophyton spp
What can Malassezia species cause?
Superficial infections in susceptible skin
Wide range of infections in immunocompromised (AIDS, transplant) and premature neonates
What is the Malassezia species?
Frequent colonisers of healthy skin, especially sebum-rich areas
What encourages growth of fungi?
Microenvironments.
What kind of environment encourages growth of fungi?
Warm and moist.
Whereabouts on the body might fungi grow?
Skin or mucous membranes.
Name another factor which can contribute to infection.
Use of broad-spectrum antibacterial agents.
This is because broad-spectrum antibacterial agents reduce competition for epithelial colonization sites in the gut
Immunosuppression can also increase fungi. Name the two types of immunosuppressant and give examples.
Iatrogenic: steroids
anti-cancer chemotherapy
solid-organ transplantation
Disease processes:
AIDS
leukaemia
endocrinopathies
->can be a combo of both types
Name some species of Candida infections.
Candida auris
Candida albicans
Candida tropicalis
Namediseases/infecions caused by Candida bacteria in humsnas.
Vaginal infection.
Skin infection.
Oral infection
Nail infection
UTI’s
Oesophagal infection
Candida species are what type of organisms?
Yeast
What can Candida albicans
Hyphae
Name the two catergories of Candida infection.
Superficial
Deep seated
give examples of superficial Candida infections.
Infections of the-
mouth, skin, nails, penis and vagina.
Give examples of deep seated infections caused by Candida.
Dissempitated infectios in seriously immunocompromised hosts e.g. neotropenia, abdominal surgery, major burns.
In which individuals can Chronic mucocutaneous Candida infection arise in?
Individuals with an unusual combination of endocrine and immune dysfunction
Aspergillosis is another type of infection caused by fungus.
Name some of the causative species
Honestly idk how many names we are expected to remember, maybe shoudl ask
Aspergillus fumigatus
Aspergillus flavus
Aspergillus nidulans (in CGD patients)
Aspergillus lentulus
Name one disease caused by Aspergillosis.
Simple asthma
What is the route of infection for Aspergillosis?
Inhalation of conidia
What is Cryptococcosis caused by?
Caused by yeast w a capsule.
What are the main causative species of Cryptococcosis?
Cryptococcus neoformans
Cryptococcus gattii
What disease does Cryptococcus neoformans cause?
pulmonary cryptococcosis (rare lung infection).
What disease is caused by Cryptococcus gattii?
Meningitis (particularly in AIDS patients)
If you have a weak immune response, what’s the strength of the host action?
High
What can happen if your body provides too strong an immune response?
Hyperinflammation. Tissues may get damaged.
Why do people develop Systemic candidosis or Acute invasive Aspergillosis?
They have too weak of an immune response.
Why do people develop Recurrent Candida vaginitis/Dermatophytosis?
They have too strong an immune response.
Name some diagnostic techniques which can be helpful in diagnosing fungal based infections.
Direct detection (histopathology, high-res CT scans)
PCR to detect fungal DNA
How can you diagnose skin infection?
Can take skin scraping and treat with potassium hydroxide to visualise the fungal bacterial elements which are resistant to hydrogen peroxide treatment.
What staining can be used in diagnosis regarding a direct smear?
PAS staining
Name a fluorescent stain which is specific to fungi.
Calcofluor White stain
Name the life saving antifungal which targets sterols.
Triazoles or allylamines
Name the life saving antifungal which targets cell wall
Echinocandins
Name the life saving antifungal which targets membrane
Polyenes
Name the life saving antifungal which targets DNA synthesis
Flucytosine
List some problems with antifungals.
Spectrum of activity
Static or cidal
IV vs oral
Toxicity
Resistance
Cost
