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Mycology I
Dr. Courtney Mycology Lecture 1
87
Medical
Graduate
04/13/2011

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Term
How many mycoses are there?  How many cause problems?
Definition
50,000; about 200, only 12-15 significant
Term
What are the two growth forms of fungi and their growth temperatures?
Definition
Yeast (37 C), Mold (20 C)
Term
What is yeast?
Definition
The unicellular growth form of fungi
Term
What are the 3 types of yeast reproduction?
Definition
nuclear fission; budding (forms blastocondida); and germ tube (forms pseudohyphae)
Term
What is a mold?
Definition
A multicellular growth form of fungi
Term
What is a conidia
Definition
a yeast spore
Term
What are the two types of mold hyphae?
Definition
Vegetative (into log) and aerial (spores released)
Term
What does dimorphic mean?
Definition
A fungi that grows as either a mold or a yeast depending on environment temperature
Term
What does dimorphic mean?
Definition
A fungi that grows as either a mold or a yeast depending on environment temperature
Term
T/F all fungi have capsules
Definition
False
Term
Fungi capsule is made up of?
Definition
polysachharides - virulence factor
Term
What is fungal cell wall made of?
Definition
Chitin
Term
What is the function of chitin?
Definition
To resist osmotic changes
Term
Medical importance of chitin cell wall (4)?
Definition
Mediates attachement, promotes colonization/invasion, is a potent antigen, mammals lack enzymes to degrade it!
Term
Unique feature of fungal plasma membrane?
Definition
Ergosterol instead of chol - target for antibiotics
Term
Name 5 components of fungal cell structure
Definition
Capsule, plasma membrane, mitochondria, nuclear envelope, and nucleus
Term
T/F fungus, not bacteria have a nuclear envelope
Definition
True
Term
T/F the fungal nuclear envelope persists during division?
Definition
True
Term
What is a hypha?
Definition
The apical polar mold outgrowth
Term
What is the main nutrient source for fungi?
Definition
Organic (carbon) compounds
Term
What is a saprophyte?
Definition
A fungi that feeds on dead materials
Term
What is a parasite?
Definition
A fungi that feeds on living materials
Term
T/F Fungi are both parasitic and saprophytic?
Definition
True
Term
How to fungi get nutrients into cells?
Definition
Fungi secrete enzymes that break down material into simple sugars and amino acids that are taken up into the cell through pores
Term
Describe the growth of a mold
Definition
hyphal growth at one end that uses both chitin synthetases and chitinase in balance
Term
T/F Fungi cell walls are flexble
Definition
False
Term
Describe Yeast growth
Definition
polar growth, usually by budding or fission
Term
A fungal allergy is a reaction to...?
Definition
proteins on the spore!
Term
T/F Humans are rarely exposed to fungal spores?
Definition
False
Term
T/F fungal growth is required to have a hypersensitivity reaction to spore
Definition
False
Term
What is an Amanita?
Definition
poisonous mushroom
Term
What are the two types of toxins made by Amanita?
Definition
amatoxins and phallotoxins
Term
What is the most deadly amatoxin and what does it target?
Definition
alpha-amantin, the liver
Term
What is the mechanism of the alpha-amantin toxin?
Definition
binds to RNA pol II and inhibits mRNA synthesis
Term
T/F heating alpah-amantin does not affect toxicity
Definition
True
Term
What is the name and target of the Aspergillus flavus toxin?
Definition
Aflatoxin, liver
Term
What is the mechanism of aflatoxins?
Definition
secretes potential carcinogens that bind DNA, prevent pairing
Term
Where are aflatoxins commonly found and what is a host besides humans?
Definition
Grain storage, livestock
Term
Where do superficial mycoses colonize?
Definition
On NON-living tissue like outermost skin layer and hair
Term
T/F superficial mycoses induce a cellular immune response?
Definition
False
Term
Name 4 common superficial fungi
Definition
pityriasis versicolor, tinea negra, black and white piedra
Term
What does Malessezia furfur cause?
Definition
pityriasis versicolor
Term
What is the presentation of pityriasis versicolor
Definition
hyper/hypo pigmented macular (small) lesions in areas rich in sebaceous glands
Term
What does Hortaea werneckii cause?
Definition
Tinea Negra
Term
What is the presentation of tinea negra?
Definition
Brown/Black spots on palms and soles
Term
Why are tinea negra macular lesions brown/black
Definition
because it produces melanin
Term
What is the presentation of black piedra?
Definition
black, rough feeling fungus on Hair Shaft
Term
What is the presentation of white piedra
Definition
Soft, white fungus on hair shaft
Term
Cutaneous mycoses caused by... and act primarily on (3)
Definition
dermatophytes, keratinized layers (skin, nails, hair)
Term
Three resevoirs for dermatophytes?
Definition
Geophilic, Zoophilic, anthrophilic
Term
What is the primary cause of damage from dermatophytes?
Definition
Inflammation of dermis, epidermis, and hair follicles
Term
Dermatophytes are aka?
Definition
Ringworm
Term
T/F Dermatophytes are the least important group of mycoses
Definition
False - they are highly prevalent
Term
What are the 3 genera of dermatophytes?
Definition
EMT - epidermophyton, microsporum, trichophyton
Term
Which dermatophyte genera have human to human transmission?
Definition
EMT - epidermophyton, microsporum, trichophyton
Term
Which dermatophyte genera have human-human and animal-human transmission?
Definition
MT - microsporum, trichophyton
Term
Which dermatophyte genera have soil-human transmission?
Definition
M - microsporum
Term
Tinea is latin for?
Definition
Worm
Term
Tinea Pedis = ?
Definition
athletes foot
Term
Tinea cruris = ?
Definition
groin, jock itch
Term
tinea corporis = ?
Definition
body
Term
tinea manus = ?
Definition
hand
Term
tinea barbae = ?
Definition
beard
Term
tinea onychomycosis = ?
Definition
nails
Term
tinea versicolor = ?
Definition
skin
Term
tinea capitis = ?
Definition
head
Term
Which tinea is common in elderly and can take 3 months to cure?
Definition
Tinea onchomycosis
Term
Which tinea is transmitted from pets (dogs) and invades hair follicles?
Definition
tinea capitis
Term
Individual differences in the presentation of tinea depends on?
Definition
Immune response of the host
Term
What is a kerion?
Definition
Site of hair loss in tinea capitis
Term
How is a fungal disease diagnosed?
Definition
Scrape ACTIVE border of growth, treat with KOH, stain and visualize on microscope
Term
What does KOH do?
Definition
Kills everything but the fungus
Term
What are the sources of subcutaneous mycoses?
Definition
soil or decaying vegetation
Term
What is required for a subcutaneous fungal infection? What forms
Definition
Trauma - lesion
Term
What are potential sites of subcutaneous fungal infection?
Definition
deeper layer of dermis, muscle, and bone (can even get into lymph)
Term
What are the 3 primary subcutaneous fungal infections?
Definition
Sporthrix schenkii, chromoblastomycosis, and subcutaneous zygomycosis
Term
What is an alternative name for Sporthrix Schenkii?
Definition
lymphocutaneous sporatrichosis
Term
Why is sporothrichosis also called the rose gardners disease?
Definition
Because the fungi is commonly found on thorns and splinters
Term
T/F Sporothrix Schenkii is a mold
Definition
False - it is dimorphic, the yeast is what colonizes body
Term
Presentation of sporotrichosis?
Definition
ulcerative nodule forms at trauma and heals, more nodules/ulcers form along lymph within two weeks
Term
Treatment for sporotrichosis?
Definition
potassium iodide - POT roses
Term
What is the presentation of chromoblastomycosis?
Definition
warty - cauliflower-like nodules appear on the surface of skin 1 month - 20 yrs after innoculation
Term
T/F Chromoblastomycosis is common in the USA?
Definition
False - common in tropical areas
Term
Resevoir of chromoblastomycosis?
Definition
Soil - you get it if you lack protective footwear
Term
Presentation of subcutaneous zygomycosis?
Definition
rubbery movable masses localized to shoulder, pelvis, hip, and thighs
Term
Resevoir of subcutaneous zygomycosis? Implantation?
Definition
traumatic implantation of fungus from plant debris
Term
T/F Subcutaneous zygomycosis is common in tropical areas?
Definition
True
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