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Mycology > Fungi Classification (Subcutaneous) > Flashcards

Fungi Classification (Subcutaneous) Flashcards

1
Q

Subcutaneous

A
  • initially involve the deeper layers of the dermis, subcutaneous tissue or bone
  • Mostly chronic
  • Extends to epidermis; not systemic
  • Lesions
  • Transmission: skin trauma; humans are accidental hosts
  • Treatment: Difficult; surgery often used
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2
Q

Subcutaneous mycoses

A 
Sporotrichosis 
Maduromycosis
Phaeohyphomycosis 
 Chromoblastomycosis
Rhinosporidiosis
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3
Q

Sporotrichosis (rose gardener’s disease)

A 
Sporothrix schenckii-  dimorphic fungus
-Chronic
-Soil, wood, plants
-Inoculation/ inhalation/ handling contaminated dressing
(not person to person)
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4
Q

Types of sporotrichosis

A

Fixed cutaneous sporotrichosis

Lymphocutaneous sporotrichosis

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5
Q

Fixed cutaneous sporotrichosis

A
  • Primary lesions at implantation site
  • Start off painless then become large ulcerate
  • Fluid discharged
  • Localized lesions; no spread to lymphatic channels
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6
Q

Lymphocutaneous sporotrichosis

A
  • Primary lesions at implantation site
  • Secondary lesions along lymphatic channels
  • Painless nodules -> small ulcerate
  • Dissemination rare; pulmonary infection if occurs
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7
Q

Specimen - Sporotrichosis

A

Specimen: unopened subcutaneous nodules / open draining lesions

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8
Q

Direct examination - Sporotrichosis

A

Reveals yeast cells (unicellular reproduced by budding)
Blood agar and sabouraud’s glucose agar slants
Antibiotic media
Animal inoculation
Colonies
Small, white -> Moist, wrinkled
Colours variable
-Cream to black
-Pigment changes when transferred to new media

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9
Q

Sporotrichosis - Hyphal vs Yeast form

A

Hyphal form
(2µ in width), branching, septate hyphae bear conidia laterally or in groups from the ends of lateral branches.
2 to 4 µ by 2 to 6µ in size
Yeast form
Use: Francis’ cystin blood agar or brain- heart infusion glucose blood agar
-develop grayish-yellow, soft-bacteria- like colonies

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10
Q

Sporotrichosis - Microscope

A

cigar shaped,
round, oval and budding cells,
Gram positive

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11
Q

Sporotrichosis - Treatment

A
  • Saturated KOH (good treatment response) 4-6ml 3 times per day
  • Itraconazole 400mg/day or terbinafine 250mg/day
  • Treatment for 1 month after cured
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12
Q

Maduromycosis

A
  • Eumycotic (true fungus)
  • Affects feet
  • Infection resembles actinomycetes (fungi like bacteria) infection
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13
Q

Maduromycosis vs actinomycotic mycetoma

A

-Organisms invade body for maduromycosis+actinomycotic mycetoma
-lesions in the
brain,
the meninges
bones.

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14
Q

Maduromycosis features

A

-Chronic
-swelling of tissue (tumefaction)
-feet, hands, butt
Allescheria boydii, can invade the blood stream in the rare instances and cause lesions of the
brain, meninges,
lungs, sinuses,
prostate, bones and other internal organs.

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15
Q

Maduromycosis Etiology

A
  • minor scratch, splinter
  • Six fungi spp <= Etiological agent
  • Mostly Saprophytic fungi in soil/plant e.g. Allescheria boydii
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16
Q

Maduromycosis Pathogenesis

A

1) Papules form first
2) Then abscesses form and envelop the foot
3) Infection can extend deeper into tissue
- Club shaped hands/feet, discoloured skin, pitted scars, nodules with oily fluid, white/yellow/black granules

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17
Q

Maduromycosis - etiology

A

Ascomycetes:
allescheria
Leptosphaeria,

Fungi imperfecti:
 Madurella,
 cephalosporium, 
Phialophora
 pyrenochoeta, 
Monosporium opiospermum
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18
Q

Actinomycotic mycetoma

A

“Lumpy-jaw” - The initial nodules formed are firm and described as “woody” or “lumpy.“

Nocardia spp. & Streptomyces spp

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19
Q

Maduromycosis - Direct exam

A

Sample
Pus from multiple draining fistulas or aspirated from un opened fluctuant areas in petri dish
- Direct exam - look for “grains” - yellow, brown, black , white
-Using a drop of water or 10% KOH
Grains contain- wide hyphae with hyphal swelling Chlamydospores
**should not be mistaken for the granule seen in actinomyeotic mycetoma ***

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20
Q

Maduromycosis media

A

sabouraud’s glucose agar at rtp

21
Q

Allescheria boydii

A 
large, round to lobulated
White to yellowish 
Rapid growth; white, cottony mycelium
Asexual conidia 
Produced singly on conidiophore ends/sides of mycelium
22
Q

Phialophora jeanselmei

A 
Grain may be 
 crescent shaped, round or ovoid
  Brown
Olive-black colony -> overgrown with olive-gray mycelium 
- Budding on primary culture
- Spores on conidiophore tips
23
Q

Treatment - Maduromycosis

A

Sulfonamide may help the actinomycotic form.

There is no effective drug against the fungal form; surgical excision is recommended.

24
Q

Phaeohyphomycosis

A

any infection caused by a dematiaceous organism (black yeast)
-subcutaneous, localized, or systemic

25
Q

Paeohyomycosis vs Chromoblastomycosis and mycetoma

A

Phaeohyphomycosis is distinguished from chromoblastomycosis and mycetoma by the absence of specific histopathologic findings such as grains in tissue.

26
Q

Paeohyomycosis - Etiology

A 
Common etiological agents of subcutaneous infection include:
Exophiala jeanselmei
Phialophora richardsial
Wangiella dermatitidis
Alternaria spp.
Bipolaris spp.
Exserohilum spp.
27
Q

Subcutaneous phaeohyphomycosis

A

-Cystic lesions

28
Q

Paranasal sinus phaeohyphomycosis

A

Bipolaris, Exserohilum, and Alternaria

29
Q

Cerebral phaeohyphomycosis

A

In immunosuppressed patients following the inhalation of conidia.

30
Q

Direct examination

A

observation of pigmented hyphae in hematoxyline-eosin or unstained histopathologic sections
-> yellowish –brown septate, moniliform hyphae

31
Q

Exophiala jeanselmei - Lab ID

A

Exophiala jeanselmei:
grow at 370C not at 400C
can utilize inorganic KNO3
grow slowly (7 to 21 days)
produces- shiny black, yeast like colonies initially.
With age, colonies become filamentous, velvety, and gray to olive to black.

32
Q

Wangiella dermatitidis

A

Wangiella dermatitidis
cultures can grow at 400C and cannot utilize KNO3 in contrast to E.Jeanselmei
Cultural characteristics the same to E.Jeanselmei
- dematiceous (dark) budding yeasts -young colony
- dematiceous hyphae + conidiogenous cells (conidia forming) + tapered tips

33
Q

Phialophora richardsial

A

Phialophora richardsial

  • Dematiaceous (dark-hyphae) organism
  • Rapid growth
  • Olive brown to brownish gray colonies
  • Brown elliptical conidia within phialides (projection from mycelia)
34
Q

Chromoblastomycosis (chromomycosis,

verrucous dermatitis)

A

variety of dematiaceous fungi

  • formation of warty cutaneous nodules which develop very slowly
  • papillomatous vegetations (tumor)
  • Lesions in lower extremities mostly
  • Tissue trauma
35
Q

Chromoblastomycosis - Etiology

A

Fonsecaea pedrosoi,
Fonsecaea compactum and
phialophora verrucosa are the three most familiar fungi

36
Q

Chromoblastomycosis - Pathogenesis

A
  • begins as a small, itchy papule which extends eccentrically and simulates a patch of ring worm
  • Months later -new lesions appear along the paths of the superficial lymphatic drainage
  • Cauliflower like appearance
37
Q

Fibrosis

A

-Scar healing in connective tissue

38
Q

Chromoblastomycosis - complications

A

Extensive fibrosis develops in the deeper tissues and the lymphatics become blocked producing elephantiasis of the extremity.

  • Painless lesions unless secondary bacterial infection
  • Spontaneous lesion healing sometimes
39
Q

Chromoblastomycosis - lab ID

A 
Skin scrapings
-10% KOH and calcofluor white mounts
Tissue sections
-stained using H&amp;E, and GMS
Interpretation
-Brown, sclerotic (cigar shaped, thick) bodies 
-Multiply by splitting not budding
40
Q

Differentiate between Chromoblastomycosis and Phaeohyphomycosis

A

-causative agent is mycelial for Phaeohyphomycosis and gains presents where chromo has sclerotic bodies

41
Q

Fonsecaea pedrosoi - strains

A

-slow- growing dark brown to black colonies
Microscopically, different strains of F.pedrosoi vary greatly based on method of conidial formation
three different methods of sporulation are recognized.
–ACP–
Arthrotheca type:
Terminal (end)cell/single lateral branches on hyphae
Swollen cells become knotted clubs that bear conidia

Cladosporium type:
Conidiophores of diff lengths bear conidia in branching chains
Single celled conidia connected via thick disjuncture

Phialophora type:
Flask-shaped conidiophores with - terminal cuplike structure bearing conidia groups

42
Q

Fonsecaea compactum

A
  • slow growth
  • short mycelium
  • terminal+lateral conidiophores with short+long branching chains of subspherical (not perfectly spherical) conidia
43
Q

Phialophora verrucosa

A

-slow growth
-greenish-brown; mat-like aerial mycelium
-Microscopically: Lateral/terminal conidia from cups at conidiophores
Flask shaped conidiophores

44
Q

Chromoblastomycosis - Treatment

A 
Surgery
Antifungal therapy (susceptibility varies depending on the genus)
			Amphotericin B		
			Flucytosine		
			Ketoconazole
Heat
45
Q

Rhinosporidiosis

A

Rhinosporidium seeberi

  • Infection of the mucous membranes of the nose, eyes, ears, larynx and occasionally the vagina, penis and skin
  • Organism has not been cultured/inoculated successuflly
  • occurs spontaneously in horses, mules and cows
  • May be carried via water
  • Children+young adults
46
Q

Rhinosporidiosis - Symptoms

A

First symptom: pain less itching sensation in the nose with profuse mucoid discharge.
Tumor masses then become pedunculated (attached) by constriction at base
-Globoid swellings on anterior area of nose
-If growth occurs in posterior nares/nostrils
—May project into posterior pharynx

47
Q

Rhinosporidiosis - Complications

A
  • Nasal obstruction, dyspnea due to swellings in posterior pharynx+larynx
  • vaginal+rectal infections resemble condylomata, hemorroids/rectal polyp
  • Lesions can persist for 35 yrs
48
Q

Rhinosporodiosis - lab ID

A

Direct examination
Specimen: polypoid mass
Result: Sporangia and spores (round-ovoid spores 7 to 9 μ , spore filled sporangia)

49
Q

Rhinosporidiosis - Treatment

A

Surgery
Ethylstilbamidine
(Local injection)

Mycology (6 decks)

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