Mycology Exam 2: SubQ + Systemic Mycoses Flashcards by Tori Bertsch

What are SubQ mycoses?

Fungal infections that are confined to the subcutaneous tissue without dissemination to distant sites, introduced by traumatic injury of the skin

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SubQ mycoses include:

Chromoblastomycosis
Sporotrichosis
Eumycotic mycetomas
Phaeohyphomycosis

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Which mycosis has tumorlike lesions resembling cauliflower?

Chromoblastomycosis

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Name some standout features of chromoblastomycosis

Cauliflower-like lesions
Sclerotic bodies - Found in tissue samples from patient

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What are sclerotic bodies?

Copper colored, septate cells that appear to be dividing by binary fission, resemble copper pennies (Associated with Chromoblastomycosis)
Found in tissue samples from the patient

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Population most affected by Chromoblastomycosis

Agricultural workers

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Etiologic agents of chromoblastomycosis

All are dematiaceous:
Cladophilophora carrionii
Fonsecacea monophora
Fonsecaea pedrosoi
Phialophora verrucosa
ALL SUBCUTANEOUS

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Lab ID of Chromoblastomycosis

Specimen = scrapings from crusted lesions
Muriform/Sclerotic bodies under microscope
Jet black underside colony

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Muriform vs Sclerotic bodies

Muriform = multicellular clusters
Sclerotic = single or double

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What is a standout feature of Fonsecaea spp? What mycose do they cause?

Cause Chromoblastomycosis
Sympodial arrangement of conidia (pedrosoi specifically)

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Sympodial growth

Conidiogenous structure that continues to increase in length by forming a new growing point just below each new terminal conidium (bent appearance)

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Standout feature of Phialophora verrucosa? What mycose does it cause?

Causes Chromoblastomycosis
Distinctive funnel-shaped, darkly pigmented collarettes

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What is the etiologic agent of Sporotrichosis?

Sporothrix schenckii

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What is another name for Sporotrichosis? Why?

Rose-gardeners disease
Transmitted by traumatic implantation of fungus into the skin associated with gardening (splinters, thorns)

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Sporothrix schenckii is a ______ fungus.

Dimorphic

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What is different about the colony morphology of Sporothrix schenckii?

Important to grow at different temperature for ID (Dimorphic)
25C = mold form (rosette)
37C = yeast like (cigar bodies)

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Differentiate between the 2 forms (mold vs yeast) of Sporothrix schenckii under a microscope

25C = mold with narrow/septate/branching hyphae, rosettelike cluster of conidia

37C = yeastlike, fusiform budding cells called cigar bodies

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Mycetoma

Chronic granulomatous infection usually involving the lower extremities, characterized by tumorlike deformities, and multiple sinus tracts draining purulent material
Purulent material contains granules called Grains

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What are the 2 types of mycetomas?

Actinomycotic (bacterial) = Nocardia, Actinomadura
Eumycotic (Fungal) = White grain mycetomas, black grain mycetomas

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What are the 2 types of Eumycotic Mycetomas and what organisms are contained within them?

White grain mycetomas: Scedosporium spp., Acremonium spp. HYALINE

Black grain mycetomas: E. jeanselmei, Madurella spp. DEMATIACEOUS

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Most common etiologic agent of White Grain Mycetomas

Scedosporium spp. (formerly Pseudoallescheria boydii)

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Standout features/key words of Scedosporium microscopic morphology.

*Also, what type of mycetoma does this organism cause?

Lollipop conidia, rarely seen cleistothecia

Causes White Grain Mycetoma (Eumycotic mycoses)

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What organism is associated with “Pacman” microscopic morphology cleistothecium?

Pseudoallescheria boydii

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Cleistothecia

Saclike structures containing asci and ascospores, when fully developed will rupture and release the asci and ascospores (PACMAN) associated with P. boydii/Scedosporium spp.

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What is the most common cause of ALL eumycotic mycetomas (including black grain AND white grain)?

Madurella mycetomatis

What is characteristic of the Black Grain Mycetoma, Madurella mycetomatis?

Brown diffusible pigment in the colony

What is characteristic of the Black Grain Mycetoma, Exophiala jeanselmei?

Microscopic morphology Young cultures = yeast like budding cells, torulose hyphae Mature cultures = tapered to a narrow elongated tip

What is the difference between organisms that cause black grain mycetomas and organisms that cause white grain mycetomas?

Black grain mycetomas: dematiaceous (pigmented) White grain mycetomas: hyaline (colorlesS)

Phaeohyphomycosis

A general term used to describe any infection caused by a dematiaceous organism

The most frequent causative agents of phaeohyphomycosis:

Exophiala jeanselmei Exophiala dermatitidis Bipolaris spp. Alternaria spp. Curvularia spp.

Moniliform hyphae

Look like "string of beads"

What are the slow growing phaeohyphomycoses? What are the rapid growing ones?

Slow growing = Exophiala Rapid growers = Alternaria, Curvularia, Bipolaris

What is characteristic about Bipolaris spp?

Phaeohyphomycose = dematiaceous Rapid growing If incubated in water at 25C = germ tube formation at one or both ends of conidia (which is why it is called Bipolaris)

What is characteristic about Alternaria spp?

Phaeohyphomycose = dematiaceous Rapid growing Drumstick-shaped conidia

What is characteristic about Curvularia spp?

Phaeohyphomycose = dematiaceous Rapid growing Twisted conidiophore Curved conidia with swollen central cell

**Be able to know some images**

What is a characteristic that most systemic mycoses share?

Dimorphism (most thermally, except Coccidioides)

What are the most common etiologic agents of systemic mycoses in the US?

1. Histoplasma capsulatum 2. Blastomyces dermatitidis 3. Coccidioides immitis 4. Paracoccidioides spp.

Which is the systemic mycoses discussed that is dimorphic, but NOT thermally?

Coccidioides immitis

What population of patients are most associated with systemic mycoses?

Immunocompromised patients

What population of people should you associate Histoplasmosis with?

Bird/chicken workers Cave spelunkers **Associated with bird and bat waste in the environment**

How is Histoplasmosis caused? (organism and mechanism)

H. capsulatum Infection acquired through inhalation of infective structures from the environment (bird and bat waste)

Where is Histoplasmosis most commonly seen? (location)

Midwest and South US

What is the disease process of Histoplasmosis?

Begins in the lung and invades the RE system (lymph nodes, liver, spleen, BM)

Lab diagnosis of Histoplasmosis

Not often seen in direct microscopic exam May be detected in BM specimens **intracellularly in mononuclear cells**

Describe key words associated with microscopic morphology of Histoplasmosis

Characteristic tuberculate macroconidia

Where is Blastomycosis most commonly seen? (location)

Mississippi, Ohio, and Missouri river valley regions

What population of people are likely to get Blastomycosis?

Outdoor occupations/activities particularly near waterways

Lab ID of Blastomycosis

Direct microscopic exam of specimen

Morphology of mold and yeast form of Blastomycosis

Mold: lollipop conidiophores Yeast: buds attached by BROAD BASE

What is another name for Coccidioidomycosis?

Valley Fever

Where is Coccidioidomycosis most commonly seen? (location)

Desert regions of US, Mexico, and Central/South America

Lab ID of Coccidioidomycosis

Direct microscopic exam of sputum or body fluid showing nonbudding, thick-walled spherule, 20-200um in diameter, containing granular material or numerous small endospores

Which systemic mycose has a colony morphology with a cobweb appearance?

Coccidioidomycosis

Describe the microscopic morphology of Coccidioidomycosis

Mature form has barrel-shaped arthroconidia that stains darkly with LPCB and **alternate arthoconidia** - separated by clear nonviable dysjunctor cells

Which systemic mycose is considered the most infectious of all fungi and extreme caution must be used in handling cultures?

Coccidioides

How may an individual contract coccidioidomycosis?

Inhalation of arthroconidia

Where is Paracoccidioidomycosis most seen? (location)

South American countries (Brazil, Colombia, Venezuela)

How may an individual contract Paracoccidioidomycosis?

Via inhalation or through trauma (trauma to oropharynx caused by vegetation chewed by some residents of endemic areas)

What is the disease process of Paracoccidioidomycosis?

Chronic granulomatous infection that begins as a pulmonary infection, then disseminates to cause ulcerative lesions of the mucous membranes

Lab ID of Paracoccidioidomycosis

Direct microscopic exam of sputum Shows characteristic mariner's wheel morphology (yeast form)

What causes Talaromycosis and what was it formerly known as?

Talaromyces marneffei, formerly known as Penicillium marneffei

Where is Talaromycosis an important and emerging pathogen?

Southeast Asia (People's Republic of China)

What is Talaromycosis associated with?

Bamboo rats

Describe Talaromycosis

Hyaline, septate, dimorphic mold

Lab ID of Talaromycosis

Cannot definitively ID based on morphologic features alone --> thermal conversion studies, NAATs **Red to maroon underside pigment of colony that diffuses into the agar is highly suggestive of this organism**