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