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Micro: Intro to Fungi and Dermatophytes


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what features differentiate fungi from other microorganisms?
they have acytoplasmic membrane which contains sterols

the cell wall lacks the muramic and techoic acids of beacterial walls INSTEAD it contains hexose, hexosamine polymersm, and chitin

they require EXOGENOUS organic energy, DO NOT contain clorophyll
How are fungi classified?
classification is based on their sexual spores

most pathogenic fungi lack a known sexual spore stage
describe the reproductive elements of DERMATOPHYTES
hyphae: septate
Sexual spore: none
Asexual spore: spores - conidia

common pathogens
Describe the reproductive elements of ZYGOMYCETES
hyphae: Aseptate

Sexual spore: zygospores

Asexual spore: sporangiospores

rare pathogens
Describe the reproductive elements of ASCOMYCETES
hyphae: SEPTATE

Sexual spore: ASCOspores

Asexual spore: Spores - conidia

Rare pathogens
Describe the reproductive elements of BASIDOMYCETES
hyphae: SEPTATE

Sexual: Basidiospores

Asexual: spores-Conidia

rare pathogens; mushrooms
what is a special charactersitic of the yeast associated with tinea versicolor?
malassezia furfur (fat loving yeast)

it can only be grown in a medium containing oil or a fatty acid
what are problems associated with the development of antifungal drugs?
fungi are eukaryotic organisms and anti fungals do not have selective toxicity
what are the 3 classes of dermatophytes?
MICROSPORUM: attack hair and skin, hair flouresces under black light; produce macroconidia (thick walled on agar)

TRICHOPHYTON: attack hair skin and nails; produce microconidia (thin walled on agar

EPIDERMOPHYTON: attacks skin and nails; produce thin walled macroconidia in banana bunches on agar
How do you treat dermatophyte infections?
Iodine, salycilic acid, benzoic acid, Whitfeilds ointment

Fatty acids

Tolnafotate = tinactin
Clotrimazole = lotrimin
what disease is caused by Sporothrix schneckii and how is it treated?
"Drunken Rose gardeners disease"

potassium iodide and oral antifungals amphotericin
In Chromoblastomycosis, the Dx is made by seeing what structures in tissue?
Cauliflower legion on skin

clusters of brown, thick walled cells (sclerotic cells) which are often aseptate, found within giant cells or extracellulary among groups of polymorphonuclear leucocytes

HISTOLOGICAL: granulomatous nodules containing giant cells and surrounded by a zone of inflammatory cells
Does Chromoblastomycosis result in bone damage?
NO there is no bone involvement
what is seen in the tissues in mycetoma? Why is this disease so devastating?
"Madura foot"

pigmented/ or non pigmented fungal black grains

has to be treated with surgery/amputation

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