6.1-SUBCUTANEOUS OVERIEW + SPOROTRICHOSIS Flashcards by Dave U.

 Infects deeper tissues like dermis and disseminating into parts of the body like lymphatic

SUBCUTANEOUS MYCOSES

How well did you know this?

Not at all

Perfectly

SUBCUTANEOUS MYCOSES
Most of the fungi causing these diseases are

dematiaceous or phaeiod. Some are hyaline or moniliaceous.

How well did you know this?

Not at all

Perfectly

All fungi under these diseases are dematiaceous (pigmented) that cause subcutaneous mycoses

Sporotrichosis
Chromoblastomycosis
Phaeohyphomycosis

How well did you know this?

Not at all

Perfectly

Mycetoma - mostly dematiaceous fungi (pigmented) except

Pseudallescheria boydii and Acremonium falciforme

How well did you know this?

Not at all

Perfectly

 Fungi that cause subcutaneous mycoses normally reside in soil or on vegetation

They are found in soil and vegetation, which is why agricultural workers, especially males, are usually infected.

SUBCUTANEOUS MYCOSES

How well did you know this?

Not at all

Perfectly

SUBCUTANEOUS MYCOSES  The fungi causing these infections are ________________in nature

saprophytic and ubiquitous

How well did you know this?

Not at all

Perfectly

SUBCUTANEOUS MYCOSES MOT:

traumatic inoculation to skin or subcutaneous

How well did you know this?

Not at all

Perfectly

General continuation of lesions from subcutaneous mycosis infections

become granulomatous and
expand slowly

How well did you know this?

Not at all

Perfectly

are localized collections of immune cells (like macrophages) that form in response to chronic inflammation or infection

granulomas

How well did you know this?

Not at all

Perfectly

Subcutaneous mycosis can become systemic?

Yes in rare cases

How well did you know this?

Not at all

Perfectly

 Species belong to Sporothrix spp. complex

o Sporothrix schenckii
o Sporothrix mexicana
o Sporothrix globosa
o Sporothrix luriei
o Sporothrix albicans
o Sporothrix inflata
o Sporothrix brasiliensis

Sexy mexicanas across the globe lure albinos to inflate them in brasil

How well did you know this?

Not at all

Perfectly

SPOROTRICHOSIS AKA

Rose Gardener’s Disease

How well did you know this?

Not at all

Perfectly

the most common form of sporotrichosis

Lymphocutaneous sporotrichosis

How well did you know this?

Not at all

Perfectly

o A thermally dimorphic fungus that lives on vegetation
 The fungi is capable of having both the yeast and mold form

Sporothrix schenckii complex

How well did you know this?

Not at all

Perfectly

SEGWAY

 C.immitis
 in some references they say that
it is not dimorphic. WHY?

C.immitis produce spherules
with spores found in the tissue INSTEAD OF YEASTS

How well did you know this?

Not at all

Perfectly

other systemic mycoses but hindi included sa lecture since the systemic mycosis it causes ay sa mga immunocompromised patients

Systemic dimorphic fungi that only infect immunocompromised patients

Taloromyces marneffei (previously
known as Penicillium marneffei)

How well did you know this?

Not at all

Perfectly

 S. schenckii grows well on routine agar media, and at RT ○

 Colonial appearance:
o Young colonies

are small, moist, and white to
cream colored

How well did you know this?

Not at all

Perfectly

 S. schenckii grows well on routine agar media, and at RT ○

 Colonial appearance:
Older colonies become

membranous, wrinkled and fuzzy with age and coarsely matted; dark brown to black with leathery consistency

How well did you know this?

Not at all

Perfectly

What type of agar media does Sporothrix schenckii grow well on?

Routine agar media

How well did you know this?

Not at all

Perfectly

What happens to the yeast phase of S. schenckii on antibiotic media?

It is inhibited

How well did you know this?

Not at all

Perfectly

Can S. schenckii grow in the presence of cycloheximide?

Yes

How well did you know this?

Not at all

Perfectly

How does S. schenckii appear on Brain Heart Infusion Agar (BHIA) at 37°C?

Soft, white, cream to tan-colored

How well did you know this?

Not at all

Perfectly

What is BHIA used for in diagnosing S. schenckii infections?

It is a biphasic medium used to demonstrate dimorphism

How well did you know this?

Not at all

Perfectly

How is dimorphism confirmed in S. schenckii?

By converting mycelial form to yeast form on BHIA or BHI-blood agar

How well did you know this?

Not at all

Perfectly

What conditions promote S. schenckii dimorphism in BHI-blood agar?

Addition of red cells, 5% CO₂, incubation at 35-37°C for 1-5 days

What is the microscopic appearance of the mycelial form of S. schenckii?

Narrow, septate hyphae with pyriform conidia arranged singly or in clusters (flowerette arrangement)

What type of conidia may be produced in older S. schenckii cultures?

Single-celled, thick-walled, black-pigmented conidia

What is the microscopic appearance of the yeast form of S. schenckii?

Small, elliptoid budding, cigar-shaped (fusiform) yeast

How long does it take to convert S. schenckii from mold to yeast form?

1 to 5 days using a medium with blood and 5% CO₂

What is the antigenic component of S. schenckii used in skin testing?

Sporotrichin

What reaction does Sporotrichin elicit in infected individuals?

Positive delayed skin reaction

How is Sporotrichin prepared?

From heat-killed saline suspensions or carbohydrate fractions

Why do some normal individuals test positive for Sporotrichin?

Due to specific or cross-reactive antibodies

What is a limitation of the Sporotrichin skin test?

False-positive results may occur

How is S. schenckii introduced into the body?

Through trauma, introducing conidia or hyphal fragments into the skin

What is the most common form of sporotrichosis?

Lymphocutaneous sporotrichosis

How does lymphocutaneous sporotrichosis progress?

Initial lesion appears on extremities Nodular and ulcerative lesions develop along lymph channels Thickening of draining lymphatics Multiple subcutaneous nodules and abscesses

What are the less common forms of sporotrichosis?

Fixed cutaneous and mucocutaneous sporotrichosis

Presence of eosinophilic material (up to 10 μm thick) radiating around yeast cells (asteroid bodies)

Splendore-Hoeppli phenomenon

What color does eosinophilic material appear under the microscope?

Pink

What stain is most commonly used for S. schenckii in histopathology?

H&E (hematoxylin and eosin)

What are the differential diagnoses for sporotrichosis skin lesions?

Mycobacterium marinum (swimming granuloma) and cutaneous leishmaniasis

How does fixed cutaneous sporotrichosis present?

Single, non-lymphangitic nodule Confined to inoculation site Common in endemic areas like Mexico Limited progression, but potential for dissemination

How does primary pulmonary sporotrichosis occur?

Inhalation of S. schenckii conidia

What condition does pulmonary sporotrichosis mimic?

Chronic cavitary tuberculosis

How can tuberculosis be ruled out in suspected pulmonary sporotrichosis cases?

Direct Sputum Smear Microscopy (DSSM) for acid-fast bacilli

Which patients are at higher risk for sporotrichosis dissemination?

Those with impaired cell-mediated immunity

What specimens are used to diagnose Sporothrix schenckii infection?

Biopsy material or exudate from granulomatous or ulcerative lesions

How is Sporothrix schenckii confirmed in culture?

By demonstrating dimorphism using BHIA with red cells

What is the characteristic microscopic appearance of Sporothrix schenckii?

Small, cigar-shaped yeast

Why is Sporothrix schenckii rarely found in KOH or calcofluor white stain?

Yeasts are not abundant in direct smears

Which stains enhance sensitivity in histopathologic sections for fungal cell walls?

Gomori methenamine silver (GMS) and periodic acid-Schiff (PAS)

What colors do fungal elements appear in GMS and PAS stains?

GMS = Black PAS = Magenta

What is the advantage of fluorescent antibody staining in diagnosing Sporothrix schenckii?

It allows direct identification of fungal elements

How does Sporothrix schenckii appear in hematoxylin and eosin (H&E) stain?

As an asteroid body with a central basophilic yeast cell and radiating eosinophilic extensions

Are GMS and PAS stains specific to Sporothrix schenckii?

What histopathologic finding is more specific for sporotrichosis?

Asteroid bodies

What is the most reliable method for diagnosing Sporothrix schenckii?

Culture

What culture media are used for isolating Sporothrix schenckii?

Sabouraud’s agar with antibacterial antibiotics

At what temperature should Sporothrix schenckii cultures be incubated?

25–30°C

How is Sporothrix schenckii confirmed in culture?

By demonstrating growth at 35°C and conversion to the yeast form

What serologic test is used to detect antibodies to Sporothrix schenckii?

Agglutination test using yeast cell suspensions or antigen-coated latex particles

Why is serologic testing for Sporothrix schenckii not always useful?

High titers do not develop early in the disease False positives can occur in previously exposed but uninfected patients

What is the principle of serologic testing for sporotrichosis?

Detection of antibodies using reagent antigen from Sporothrix schenckii

Is Sporothrix schenckii infection always treated?

No, some cases are self-limited

What is the treatment of choice for sporotrichosis?

Oral Itraconazole or another azole antifungal

What alternative treatment is effective for sporotrichosis?

Oral saturated solution of potassium iodide (in milk)

What antifungal is used for systemic Sporothrix schenckii infections?

Amphotericin B

Where is Sporothrix schenckii commonly found in nature?

Sphagnum moss Rose thorns Decaying wood Pine straw Prairie grass Other vegetation

What percentage of sporotrichosis cases occur in males?

75%

Which occupations are at higher risk for sporotrichosis?

Agricultural workers Forest rangers Horticulturists Other similar occupations

How can sporotrichosis be prevented?

Minimizing accidental inoculation Using fungicides