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Microbiology > Mycology Exam 2: SubQ + Systemic Mycoses > Flashcards

Mycology Exam 2: SubQ + Systemic Mycoses Flashcards

1
Q

What are SubQ mycoses?

A

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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2
Q

SubQ mycoses include:

A

Chromoblastomycosis
Sporotrichosis
Eumycotic mycetomas
Phaeohyphomycosis

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3
Q

Which mycosis has tumorlike lesions resembling cauliflower?

A

Chromoblastomycosis

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4
Q

Name some standout features of chromoblastomycosis

A

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

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5
Q

What are sclerotic bodies?

A

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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6
Q

Population most affected by Chromoblastomycosis

A

Agricultural workers

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7
Q

Etiologic agents of chromoblastomycosis

A

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

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8
Q

Lab ID of Chromoblastomycosis

A

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

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9
Q

Muriform vs Sclerotic bodies

A

Muriform = multicellular clusters
Sclerotic = single or double

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10
Q

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

A

Cause Chromoblastomycosis
Sympodial arrangement of conidia (pedrosoi specifically)

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11
Q

Sympodial growth

A

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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12
Q

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

A

Causes Chromoblastomycosis
Distinctive funnel-shaped, darkly pigmented collarettes

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13
Q

What is the etiologic agent of Sporotrichosis?

A

Sporothrix schenckii

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14
Q

What is another name for Sporotrichosis? Why?

A

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

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15
Q

Sporothrix schenckii is a ______ fungus.

A

Dimorphic

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16
Q

What is different about the colony morphology of Sporothrix schenckii?

A

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

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17
Q

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

A

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

37C = yeastlike, fusiform budding cells called cigar bodies

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18
Q

Mycetoma

A

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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19
Q

What are the 2 types of mycetomas?

A

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

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20
Q

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

A

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

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

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21
Q

Most common etiologic agent of White Grain Mycetomas

A

Scedosporium spp. (formerly Pseudoallescheria boydii)

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22
Q

Standout features/key words of Scedosporium microscopic morphology.

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

A

Lollipop conidia, rarely seen cleistothecia

Causes White Grain Mycetoma (Eumycotic mycoses)

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23
Q

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

A

Pseudoallescheria boydii

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24
Q

Cleistothecia

A

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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25
Q

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

A

Madurella mycetomatis

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26
Q

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

A

Brown diffusible pigment in the colony

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27
Q

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

A

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

28
Q

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

A

Black grain mycetomas: dematiaceous (pigmented)

White grain mycetomas: hyaline (colorlesS)

29
Q

Phaeohyphomycosis

A

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

30
Q

The most frequent causative agents of phaeohyphomycosis:

A

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

31
Q

Moniliform hyphae

A

Look like “string of beads”

32
Q

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

A

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

33
Q

What is characteristic about Bipolaris spp?

A

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)

34
Q

What is characteristic about Alternaria spp?

A

Phaeohyphomycose = dematiaceous
Rapid growing
Drumstick-shaped conidia

35
Q

What is characteristic about Curvularia spp?

A

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

36
Q

Be able to know some images

A
37
Q

What is a characteristic that most systemic mycoses share?

A

Dimorphism (most thermally, except Coccidioides)

38
Q

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

A
  1. Histoplasma capsulatum
  2. Blastomyces dermatitidis
  3. Coccidioides immitis
  4. Paracoccidioides spp.
39
Q

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

A

Coccidioides immitis

40
Q

What population of patients are most associated with systemic mycoses?

A

Immunocompromised patients

41
Q

What population of people should you associate Histoplasmosis with?

A

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

42
Q

How is Histoplasmosis caused? (organism and mechanism)

A

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

43
Q

Where is Histoplasmosis most commonly seen? (location)

A

Midwest and South US

44
Q

What is the disease process of Histoplasmosis?

A

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

45
Q

Lab diagnosis of Histoplasmosis

A

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

46
Q

Describe key words associated with microscopic morphology of Histoplasmosis

A

Characteristic tuberculate macroconidia

47
Q

Where is Blastomycosis most commonly seen? (location)

A

Mississippi, Ohio, and Missouri river valley regions

48
Q

What population of people are likely to get Blastomycosis?

A

Outdoor occupations/activities particularly near waterways

49
Q

Lab ID of Blastomycosis

A

Direct microscopic exam of specimen

50
Q

Morphology of mold and yeast form of Blastomycosis

A

Mold: lollipop conidiophores
Yeast: buds attached by BROAD BASE

51
Q

What is another name for Coccidioidomycosis?

A

Valley Fever

52
Q

Where is Coccidioidomycosis most commonly seen? (location)

A

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

53
Q

Lab ID of Coccidioidomycosis

A

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

54
Q

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

A

Coccidioidomycosis

55
Q

Describe the microscopic morphology of Coccidioidomycosis

A

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

56
Q

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

A

Coccidioides

57
Q

How may an individual contract coccidioidomycosis?

A

Inhalation of arthroconidia

58
Q

Where is Paracoccidioidomycosis most seen? (location)

A

South American countries (Brazil, Colombia, Venezuela)

59
Q

How may an individual contract Paracoccidioidomycosis?

A

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

60
Q

What is the disease process of Paracoccidioidomycosis?

A

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

61
Q

Lab ID of Paracoccidioidomycosis

A

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

62
Q

What causes Talaromycosis and what was it formerly known as?

A

Talaromyces marneffei, formerly known as Penicillium marneffei

63
Q

Where is Talaromycosis an important and emerging pathogen?

A

Southeast Asia (People’s Republic of China)

64
Q

What is Talaromycosis associated with?

A

Bamboo rats

65
Q

Describe Talaromycosis

A

Hyaline, septate, dimorphic mold

66
Q

Lab ID of Talaromycosis

A

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

Microbiology (24 decks)

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