Mycology Exam 2: SubQ + Systemic Mycoses Flashcards
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
SubQ mycoses include:
Chromoblastomycosis
Sporotrichosis
Eumycotic mycetomas
Phaeohyphomycosis
Which mycosis has tumorlike lesions resembling cauliflower?
Chromoblastomycosis
Name some standout features of chromoblastomycosis
Cauliflower-like lesions
Sclerotic bodies - Found in tissue samples from patient
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
Population most affected by Chromoblastomycosis
Agricultural workers
Etiologic agents of chromoblastomycosis
All are dematiaceous:
Cladophilophora carrionii
Fonsecacea monophora
Fonsecaea pedrosoi
Phialophora verrucosa
ALL SUBCUTANEOUS
Lab ID of Chromoblastomycosis
Specimen = scrapings from crusted lesions
Muriform/Sclerotic bodies under microscope
Jet black underside colony
Muriform vs Sclerotic bodies
Muriform = multicellular clusters
Sclerotic = single or double
What is a standout feature of Fonsecaea spp? What mycose do they cause?
Cause Chromoblastomycosis
Sympodial arrangement of conidia (pedrosoi specifically)
Sympodial growth
Conidiogenous structure that continues to increase in length by forming a new growing point just below each new terminal conidium (bent appearance)
Standout feature of Phialophora verrucosa? What mycose does it cause?
Causes Chromoblastomycosis
Distinctive funnel-shaped, darkly pigmented collarettes
What is the etiologic agent of Sporotrichosis?
Sporothrix schenckii
What is another name for Sporotrichosis? Why?
Rose-gardeners disease
Transmitted by traumatic implantation of fungus into the skin associated with gardening (splinters, thorns)
Sporothrix schenckii is a ______ fungus.
Dimorphic
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)
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
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
What are the 2 types of mycetomas?
Actinomycotic (bacterial) = Nocardia, Actinomadura
Eumycotic (Fungal) = White grain mycetomas, black grain mycetomas
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
Most common etiologic agent of White Grain Mycetomas
Scedosporium spp. (formerly Pseudoallescheria boydii)
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)
What organism is associated with “Pacman” microscopic morphology cleistothecium?
Pseudoallescheria boydii
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.
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?
- Histoplasma capsulatum
- Blastomyces dermatitidis
- Coccidioides immitis
- 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
