Flashcards in 12.7: Mycology I Deck (55)
Structure of fungi?
- Nucleus / nuclear membrane / chromosomes
- Rigid chitin cell wall
- Cytoplasmic organelles
- Ergosterol is main sterol
Only microorganisms with chitin in cell wall?
How can fungi produce a sexually?
1. Single celled yeast bud
2. Hyphae break off and grow on own
3. Hyphae can also produce fruiting bodies: spores
What is mycelium?
Collection of multiple hyphae
What forms of fungi produce hyphae?
What forms of fungi produce Blastoconidia / germ tubes?
What is dimorphism?
Fungi can take on mould or yeast form
1. Yeast at 35 degrees in body fluid
2. Mold at 25 degrees in lab temp
2 main types of spores?
1. Sporangiospores: Zygomycete species
- Sack full of spores that will burst
2. Conidia: Aspergillus species
- Strings of spores
Structure of Sporangiospores?
- Column known as sporangiophore comes off hyphae
- Sack on end known as sporangium
- Sporangiospores contained inside
- Sack will burst to release spores
***Seen in Zygomycete species
Structure of Conidia?
- Column known as conidiophore comes off hyphae
- Vesicle swells off conidiophore with tubular phialides on end
- Conidia come off this like string of spores
***Seen in aspergillus species
What are arthroconidia?
- Pieces of hyphae that break off to form sporing structure
Why do humans need to eat so much?
Takes a lot of energy to keep body temp up
Why are humans immune to some fungi?
- Our body temp is to warm for them to grow
- May have protected us from fungi in time of dinosaurs
How can fungal infection be spread?
1. Human to human: athletes food
2. From environment
3. Contact with animals
What is found in bird droppings?
Pathogenesis of fungi?
- Use adhesions to stick to mucus membrane
- Invade via trauma, inhalation, catheters
Histoplasm interaction with macs?
- Are phagocytosed but multiply in macs
What type of immunity is needed to prevent fungal infection?
- Cellular immunity needed to eradicate infection
- Humoral immunity not protective
What is most common fungal pathogen?
- Normal flora of GI/GU
When is germ tube found?
- Only in candida albicans
Only candida not producing hyphae?
- Associated with UTIs
- Resistant to fluconazole
Candid associated with HIV?
Go to drug for candida infections?
***Glabrata is resistant
Pathogenesis of candida?
1. Mucosal adherance
2. Lytic enzymes for keratin for invasion of epithelium
3 Bind to fibrin/collagen using adhesin
4. Bind to C3b making unavailable for opsonization
Host defenses for candida?
1. Intact skin
2. Normal GI flora: bost antibiotic infection
3. Candid cell wall manin activating complement path, IgG, and hypersensitivity
What cells are key in defending from candida?
Neuts and macs
What is mucocutaneous forms of candida associated with?
Defect in cell mediated immunity
What is systemic forms of candida associated with?
Risk factors of candida?
4. Low T cell function