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
Where can candida effect?
7. Systemic: heart, lungs etc
What is thrush?
Fungal (yeast) infection of mouth and tongue causing white patches
What is chronic mucocutaneous candidiasis?
- Hereditary T cell deficiency
- Consistent fungal infections from infancy
- Thrush and diaper rash first signs
- Disfiguring rashes
What is candida endophthalmitis?
- Candida infection of eye that can lead to blindness
Lab diagnosis of candida albicans?
- Production of germ tube
- Calcofluor stain from chitin in cell wall
- Poor gram stain with pseudohyphae
- White smooth colony on sabouraud dextrose agar
What is yeast with pseudohyphae indicative of?
Invasive yeast infection in contrast to normal flora of body
Most common mold?
- Mold that is in air we note in summer air counts
- Count inside should be lower than outside
- Rapidly growing mold w/ septate hyphae and dichotomous branching
- Found in soil, air, construction dust and inhaled
Clinical manifestations of aspergillus?
1. Allergy from high spore count inair
2. Fungus ball in preexisting cavity
3. Systemic infection
Common specie for aspergillus? ID?
- Blue green fuzzy mold on agar
- Conidiophores on microscopy
What are mucormycosis?
- Blood vessel invading fungi that are very deadly
What is the most common mucormycosis?
- Causes acute, often fatal infection
- Invade vessels leading to ischemia, necrosis, and infarc
- Lead to black puss formation
Who is at risk for Rhizopus?
1. HSC transplan/ solid organ
3. Acidosis in diabetics
What should not be administered in mucormycosis?
- Fe or blood products
How is mucormycosis treated?
- Surgery to debride tissues
- Often very disfiguring
- Ribbon like structure with no septum
- Branch at 90 angle
- Wooly white and gray growth
- Express sporangia containing sporangiospores
Another term for Dermatophytosis?
- Fungal infection of keratinized structure: skin, hair, nails
- Invasive growth is rare
- Transmitted by close personal contact
Another name for ringworm?
3 genre of Dermatophytes?
Appearance of Dermatophytosis?
- Circular rash with inflammation greatest at periphery
How to collect sample of Dermatophytosis?
- Scrape skin at edge where there is most inflammation / fungus
What does "Tinea" before a body part mean?
- Dermatophytosis of that body part
Most common form of Dermatophytosis?
"Tinea Pedis" / "Athlete's foot"
- Weeping peeling lesion between toes
- Itching and burning of feet
What is tinea capitis?
- Dermatophytosis of hair / scalp
What is tinea cruris?
Infection of groin area: Jock itch