Introduction to Fungi Flashcards
What can fungi infect?
- Plants
- Insects
- Amphibians
- Mammals
What is mycology?
The study of fungi
What is a fungi?
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 egosterol as the major sterol.
What are the 3 groups of fungi?
- Basidiomycetes
- Ascomycetes
- Zygomycetes
What are the sexual and asexual spores of each group?
Basidiomycetes -S:basidiospores -A:conidium Ascomycetes -S:ascospores -A:conidium Zygomycetes -S:zygospore -A:sporangiospores
What are examples of ascomycetes?
- Candida
- Aspergillus spp
What is an example o of a basidiomycete?
Crytococcus species
What is an example of a zygomycete/
Rhizopus species
What are yeasts?
Fungi that favour a unicellular habit
What non-fatal diseases can fungi cause?
-Athletes foot: Epidermophyton, Microsporum and Trichophyton spp
-Thrush:Candida
Pityriasis veriscolor: Malssezia spp
What are ringworm infections usually called?
Tinea…
What is dermatophytosis caused by?
Moulds with a dredilection to degrade keratin as a nutrient source
What are the causative agents of dermatophytosis?
- Epidermophyton
- Microsporum
- Trichophyton spp
What is the causative agent of pityriasis veriscolor?
Malassezia spp
What is pityriasis veriscolor caused by?
Yeasts that also form hyphae in infected skin
What group of immunocompromised individuals does Candida species affect?
Infect deep organs of patients with various types of immune dysfunction e.g. after abdominal surgery, burns
What group of immunocrompromised individuals does Aspergillus species affect?
Infect deep organs of patients undergoing chemotherapy and stem cell transplantation
What factors contribute to pathogenicity of fungal infections?
- Favourable micro-environments
- Broad-spectrum antibacterial agents reduce competition for epithelial colonisation sites in gut
- Immunosuppression
What are examples of iatrogenic immunosuppression of host defenced?
- Steroids
- Anti-cancer chemotherapy
- Solid-organ transplantation
What are examples of disease process that can immunosuppress host defenced?
- AIDS
- Leukaemia
- Endocrinopathies
Describe candida specie.
- Commensal to GI tract
- Most infections are enogenous
- Candida spp are yeasts
- C.albicans can form hyphae
What infections can Candida spp cause?
- Superficial of mouth, vagina, penis, skin, nails
- Deep-seated: disseminated infections in seriously immunocompromised hosts
How can chronic mucocutaneous Candida infections arise?
In individuals with an unusual combination of endocrine and immune dysfunction
Describe aspergillus spp.
- Moulds
- Ubiquitous in the environment: infection occurs by spore inhalation
- strongly angioinvasive
What is invasive pulmonary aspergillosis mainly associated with?
Haemotological malignancy
What diagnostic methods are used in mycology?
- Direct detection (histopathology, CT)
- Detection of circulating fungal antigens
- Detection circulating antibodies to fungi
- PCR for fungal DNA
- Culture of fungus from normally sterile site
