Subcutaneous MycosesM

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Prepared By:NIZAQAT FAROOQ

Subcutaneous Mycoses


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Subcutaneous Mycoses

These are caused by fungi that grow in soiland on vegetation and are introduced intosubcutaneous tissue through trauma.


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sporotrichosis

Sporothrix schenckii is a dimorphicfungus that live on decaying vegetation.When introduced into the skin, typically bya thorn, it cause a local pustule or ulcerwith nodules along the draining lymphatics

.


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sprotrichosis

Sporotrichosis, infection with the fungus

Sporothrix schenckii.


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sporotrichosis

Sporotrichosis ulcer.


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sporotrichosis

Disseminated infection such as visceral,osteoarticular, meningeal and pulmonarysporotrichosis is often seen in patients withunderlying diseases, including alcoholism,diabetes mellitus, hematologic malignancy, theuse of immunosuppressive agents, chronic

obstructive pulmonary disease, and HIVinfection.


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The extracutaneous form is rare andresults from inhalation of conidia orhematogenous seeding from a deepinoculation.


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The diagnosis is established by culture ofthe organism from the site of infection.

Sputum, synovial fluid, CSF, biopsyspecimens , exudates and, rarely, bloodhave been reported to yield S.schenckii

when cultured.Growth of the organism may occur within3 5 days.


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At 25 30 C, the fungus grows as a mould.Colonies rapidly grow and are smooth andwrinkled with a dirty whitish color.

colonies are slow growing, moist with awrinkled and folded surface. Some strainsmay produce short aerial hyphae andpigmentation may vary from white tocream to black.


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Conidiophores arise at right angles fromthe thin septate hyphae and are usuallysolitary, erect and tapered towards theapex. Conidia are formed in clusters ontiny denticles by sympodial proliferation ofthe conidiophore, their arrangement oftensuggestive of a flower.


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In vivo and in supplemented agar, such asBHI or BCG agar at 37 C, S. schenckiiexists as a yeast.

In this form, the colonies are off-whitewith a creamy texture and the organismreproduces by budding.

The yeast form is 4 6 m in diameter andis often cigar-shaped.


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Section from a fixed cutaneous lesion withsporotrichosis showing round Periodic Acid-Schiff (PAS) positive yeast-like cells,one with an elongated bud.


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Chromomycosis

This is a slowly progressive granulomatousinfection that is caused by several soil fungi(Fonsecaea, phialophora, cladosprium, etc )when introduced into the skin through thetrauma. These fungi are collectively calleddematiaceous fungi, so named because theirconidia or hyphae are dark-colored, eithergray or black.


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Chromomycosis

Chromoblastomycosis.


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Chromomycosis

"Chromoblastomycosis, syn.

chromomycosis; hyperkeratotic lesionsfoot; Fonsacaea (Phialophora) infection,


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Chromomycosis

Wartlike lesion with crusting abscessesextend along the lymphatics. The disease

occur mainly in the tropics and is found onbare feet and legs. Specimens include biopsymaterial or exudate from granulous or ulcerativelesions.

Black dots may be observed on the surface oflesions; samples of material from these areasare particularly useful for microscopicexamination.


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chromoblastomycosis is characterized bythe presence of unique sclerotic bodiesin involved tissues. Sclerotic bodies (5 12m in diameter) are chestnut brown,round, thick-walled structures that aremuriform (they have both horizontal andvertical septa).


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The specimen should be plated on culturemedia both with and without antibioticsbecause of the possibility of bacterialcontamination, and inoculated platesshould be incubated at both 25 C and30 C. In most cases, colonies are formedwithin 2 weeks.


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All of these causative agents producesimilar slow-growing dark brown orolivaceous to black colonies with a velvetytexture.


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mycetomaSoil organisms ( petriellidium,

madurella ) enter through wounds in

the feet, hands, or back and causeabscesses, with pus dischargethrough sinuses. The pus contain

compact colored granules.


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Diagnose

characterized by draining sinuses thatextrude masses of the infecting organismtermed granules, grains or sclerotia.


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the name Madura foot was proposedbecause it was the term used to describethe disease in Indias Madura district.

The clinical hallmarks of mycetoma areswelling, draining sinuses, and granules,which are microcolonies of the etiologicagent that are extruded through thesinuses.


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the granulomatous inflammation willextend to involve bone and may causedestructive lesions, but bone involvementis less extensive in eumycotic comparedwith actinomycotic mycetoma. Ligamentsmay also be involved, but muscle andtendons normally remain intact ineumycotic mycetoma.


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mycetoma Actinomycete such as nocardia can

cause similar lesions (Actinomycoticmycetoma).There is no effective drugagainest the fungal form; surgicalexcision is recommended.


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mycetoma

Mycetoma of the arm.


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mycetoma

Mycetoma ofthe shoulderand back.


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MYCETOMACausative agents

INFECTIOUS AGENTSMadurella mycetomatisPseudallescheria boydii

LESS COMONAcremoniumLeptosphaeriaAspergillus


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: Madurella mycetomatis causes the majority ofthe cases with the black grains. It is

dematiaceous mold with brown colonies and

diffused honey-colord pigment.

Madurella grisea : another species of madurella

similar to mycetomatis but with grey colonies


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Pseudoallescheria boydii : causes whitegrain mycetoma.


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Khaled Moghraby

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Subcutaneous MycosesM