Intro to Mycoses
How do you distinguish chromoblastomycosis from phaeohyphomycosis based on morphology?
1. Chromoblastomycosis is sclerotic or medlar body in tissue form 2. Phaeohyphomycosis is myceliail (pigmented septate hyphal fragments)
What are the causative agent(s) of chromoblastomycosis?
1. Fonsecaea 2. Phialophora 3. Cladophialophora
What are the 3 common etiologies of dermatophytosis and what do they usually infect?
1. Microsporum (hair, skin) 2. Epidermophyton (skin, nail) 3. trichophyton (hair, skin, nail)
How are dermatophytoses usually transmitted?
1. close human contact (direct) 2. Sharing clothes, towels, sheets (indirect) 3. Zoophillic
Describe the cell wall of fungi
1. composed of chitin, glucans, mannans. antigenic. provides rigidity, shape, strength
What is the transmission of black piedra?
Environmental (frequent tropical areas)
T/F: fungal organisms generally stain gram negative
False, fungal organisms generally stain gram positive
T/F: there are a variety of fungi, and most of them are associated with human disease
False, there are a variety of fungi, yet very few of them are associated with human disease
T/F: tinea versicolor will grow on regular media
False, tinea versicolor is lipophillic and requires a lipid source to grow
What is the transmission for tinea versicolor?
Human to human
What are the clinical findings for tinea versicolor?
Hyper/hypopigmented maculae typically on trunk and proximal limbs. Usually not pruritic or symptomatic
What is the etiology of tinea versicolor?
Malassezia furfur complex
what is the etiology of black piedra?
Piedra hortae
What is diagnostic of chromoblastomycosis?
Sclertoic body (muriform cell/medular body) in tissue form
What fungi has cigar shaped yeast form at 37 degrees
Spirothrichosis
Is white piedra a superficial, cutaneous, or subcutaenous infection?
Superficial
Is Tinea Versicolor a superficial disease, cutaneous disease, or subQ disease?
Superficial (stratum corneum)
T/F: both chromoblastomycosis and phaeohyphomycosis are post-traumatic mycotic infections caused by dematiaceous fungi
True
T/F: fungi are abundant and widely distributed in the environment
True
T/F: some fungi have antiphagocytic polysaccharide capsules
True
can exist as either a yeast or a mould depndending upon growth conditions
True
tinea barbae
beard
what does culture show for tinea nigra?
black colonies
tinea corporis
body
What are the clinical findings of tinea nigra?
brownish macula on palms and soles (looks like superficial melanoma)
what does calcofluor white bind to?
chitin in fungal cell wall
What is cultured using sabouraud dextrose agar?
chromoblastomycosis
What does microscopy for tinea nigra indicate?
darkly pigmented branched septate hypheae with ELONGATED BUDDING CELLS
what is GMS (gomori methenamine silver) stain useful for?
detecting fungi in tissue specimens
What is the mechanism of dermatophytoses?
digest/hydrolyze keratin using keratinases and use as nutrition
What are the clinical findings of black piedra?
discrete, hard, dark brown to black nodules on the hair
What is the purpose of KOH?
dissolves human cells
What are clinical findings suggestive of eumyctema (madura foot)?
draining sinuses containing granules
What is the transmission of tinea nigra?
environment (more common tropical/subtropical)
What is the transmission of sporothrichosis?
environmental (frequently found in soil, gardeners)
Are fungi prokaryotic or eukaryotic organisms?
eukaryotic
tinea capitis
head
What is the etiology of tinea nigra?
hortae (exophiala) werneckii
What cutaneous mycoses have a risk factor of barefeet?
madura foot, chromoblastomycoses
What is the transmission of chromoblastomycosis?
most common in barefoot populations in tropical areas (environmental)
multicellular organisms that reproduce by forming aerial hyphae and conidia, grow by producing septate or non-septate hyphae
moulds
What are the clinical findings of sporothrichosis?
nodule/ulcer, can progress to lymphatic tissue
what does microscopy for white piedra indicate?
non-pigmented hypheae
tinea unguium
onchymycosis (nails)
What are clinical findings of chromoblastomycosis?
papules to warty nodules to verrucous cauliflower like lesions on lower extremities
What is the etiology of white piedra?
piedra trichosporon
Describe superficial mycoses in general
primarily a cosmetic problem with little to no host reaction that are easily diagnosed and treated
What does microscopy for black piedra indicate?
septate pigmented hyphae
How is tinea versicolor diagnose?
skin scraping (yeast like forms and hyphal fragments both seen on KOH prep)
What are the clinical findings of white piedra?
soft, white to yellowish nodules loosely attached to the hair
What fungi has rosette like clusters of conidia at 25 degrees?
spirothricosis
What fungi is often found in gardeners following minor trauma?
spirothricosis
What is the etiology of sporothrichosis?
sporothrix schenikii
Is tinea nigra a superficial, cutaneous or SubQ infection?
superficial (straum corneum)
Which grows at higher temperatures: yeast or moulds/
yeast
unicellular, round/oval organisms that reproduce by budding
yeasts