Exophiala Fungi Overview

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Questions and Answers

What temperature condition is specifically required for the growth of Exophiala jeanselmei?

40°C to 42°C

37°C and 40°C

35°C to 37°C

Only at 37°C (correct)

Which characteristic distinguishes Exophiala dermatitidis from Exophiala jeanselmei?

Shape of conidiophore

Color of colonies (correct)

Presence of potassium nitrate

Growth temperature

What is the shape of the conidia produced by Exophiala species?

Rough and irregular

Cigar-shaped forms (correct)

Elongated and tapered

Round and smooth

Which method is useful for detecting melanization in fungal organisms?

Fontana-Masson stain Signup and view all the answers

Which of the following is true for Exophiala dermatitidis?

It can grow at temperatures up to 42°C. Signup and view all the answers

Which characteristic is associated with Exserohilum?

Gray-green to dark-brown colonies Signup and view all the answers

What describes the appearance of Alternaria conidia?

Large brown conidia resembling a drumstick Signup and view all the answers

What is a distinguishing feature of Curvularia?

Golden brown, multi-celled, and curved conidia Signup and view all the answers

Which fungi feature is described as having bent conidiophores?

Bipolaris Signup and view all the answers

Which feature is NOT characteristic of the diagnostic methods for mycoses?

Golden-brown hyphae without septation Signup and view all the answers

Which of the following genera is identified with multiple celled and swollen central cell characteristics?

Curvularia Signup and view all the answers

What feature is crucial in identifying exophiala species?

Gray-green to dark-brown colonies Signup and view all the answers

Which description accurately completes the identification of Bipolaris?

Protruding hilum with germ tubes at both ends Signup and view all the answers

Which species is known for having a cleistothecial structure in its sexual form?

Pseudallescheria boydii Signup and view all the answers

What is the typical characteristic of the conidia produced by Cladophialophora?

Lemoniform to fusiform and slightly verrucous Signup and view all the answers

Which of the following best describes the infection caused by eumycotic mycetomas?

Localized and can lead to chronic granulomatous infection Signup and view all the answers

Which genus is associated with branching, single-celled conidiophores?

Cladophialophora Signup and view all the answers

In which regions are eumycotic mycetomas most commonly found?

Tropical and subtropical areas Signup and view all the answers

Which of the following conidia measurements is typical for Phialophora?

3-5 by 1.5-3.5 micrometers Signup and view all the answers

Which characteristic is NOT associated with Rhinocladiella aquaspersa?

Found exclusively in soil Signup and view all the answers

What type of infection is primarily caused by fungi in those with outdoor occupations?

Subcutaneous and cutaneous infections Signup and view all the answers

Study Notes

Exophiala

Exophiala jeanselmei is a slow growing fungus that produces shiny brown, velvety colonies with age
It has elongated conidiophores with tapered tips, utilizes potassium nitrate, and grows only at 37°C

Exophiala dermatitidis

Slow grower
Produces shiny black colonies that appear velvety with age
Has elongated tubular annellophores
Does not use potassium nitrate
Grows at 37°C, 40°C, and 42°C

Conidia of Exophiala spp.

Conidia bud at the tips of annelides

Conidia of Exophiala dermatitidis

Yeast form: 2 to 4 μm in diameter, oval or elliptical in shape, often with a single bud
Cigar-shaped forms measuring 3 to 10 μm

Yeast & Mold Phases of S. dermatitidis

Colonies are gray-green to dark-brown

Dematiaceous Genera Inciting Subcutaneous Phaeohyphomycosis

Exserohilum: Gray-green to dark brown colonies
Alternaria: Golden-brown hyphae, large brown conidia resembling a drumstick, with horizontal and longitudinal septa

Cleistothecia Containing Ascospores

Appear as a drumstick with alternating dark and light horizontal and longitudinal septa

Curvularia

Geniculate conidiophores
Conidia: Golden-brown, multi-celled, curved, and have a swollen central cell

Bipolaris

Bent conidiophores
Oblong conidia arranged sympodially
Hilum protrudes slightly
Germ tubes present at one or both ends

Cladophialophora carrionii

Erect conidiophore
Single celled and branching

Rhinocladiella aquaspersa

Erect conidiophore
Dark in color, conidia located only on the upper portion near the tip of conidiophore
Elliptical, single-celled, and sympodially arranged

Phialophora vs. Cladophialophora

Phialophora: Conidia measure 3-5 by 1.5-3.5 micrometers, aggregated and clustered at the apices of the phialide
Cladophialophora: Lemoniform to fusiform, smooth, slightly verrucous, pale olivaceous

Phialophora verrucosa

Flask-shaped phialide
Collar-like structure (colorette)
Conidia

Eumycotic Mycetomas

Uncommon in the United States
Subcutaneous and cutaneous tissue infections
Swelling and exudates draining to the skin surface
Mostly found in tropical and subtropical areas
Infections occur in individuals with outdoor occupations
Chronic granulomatous infection, commonly involving the lower extremities
Dissemination may occur, but it is rare
Most common:
- Pseudallescheria boydii (teleomorph): Sexual form, cleistotheicia
- Scedosporium boydii(anamorph): Asexual form, single oval conidia

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Description

Explore the characteristics and growth conditions of the Exophiala genus, including Exophiala jeanselmei and Exophiala dermatitidis. This quiz covers their morphological features, conidia forms, and classification within dematiaceous fungi related to phaeohyphomycosis.