Overview

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Overview

• Superficial
• Tinea versicolour
• Tinea nigra
• Black and white piedra
• Cutaneous
• Subcutaneous
• Systemic
• opportunistic

onychomycosis
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Fungi by the Tristram scheme
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Subcutaneous mycoses (M4.1)

• Subcutaneous tissue (beyond just skin)
• Aetiology - is diverse / environmental
• Organisms of low innate pathogenicity
• traumatic implantation, chronic, non
  transmissible.
• Pathology
• May be a non specific foreign body reaction
• May be a distinct clinical / microbial entity

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Subcutaneous mycoses (M4.1a)

• Sporotrichosis
• Distinct disease with Sporothrix schenkii.
• Chromoblastomycosis
• Distinct disease with various dematiaceous fungi
  AND specific tissue fungal morphology.
• Mycetoma
• Eumycotic and actinomycotic
• Specific clinical presentation.
• Phaeohyphomycosis
• Brown hyphae in tissue

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Sporotrichosis (M4.2)

• Sporothrix schenkii - dematiaceous/dimorphic
• Reservoir - soil, decaying vegetation, worldwide
  distribution
• Transmission
• Traumatic implantation, occupational
• Clinical
• Subcutaneous nodules
• Suppuration, ulceration and drainage
• Spread down lymphatic course.

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Laboratory diagnosis (M4.3)

• Direct microscopy
• Poor sensitivity. Sparse yeast cells, asteroid
  body
• Culture
• Good yield and grows on most media
• Room temp for isolation (37oC is slower)
• Identification
• A white to grey mold becoming moist
• Hyaline hyphae, mixed hyaline/demat conidia
• Need in vitro conversion to yeast

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Chromoblastomycosis (M4.4)

• Classified by presence of fungal tissue form AND
  clinical presentation, NOT aetiology
• Aetiology - any dematiaceous fungi
• e.g Cladosporium, Fonsecaea, Phialophora
• NOT all subcutaneous infections with these
  organisms are chromoblastomycosis

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Chrmoblastomycosis (M4.4b)

• Tissue form is SCLEROTIC body
• Dematiaceous thick walled yeast cell
• Non budding, but multiplane septation

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Chromoblastomycosis (M4.5)

• Reservoir and transmission
• Traumatic implantation from decaying vegetation,
  but chronicity dictates that it is uncommon in
  developed countries.
• Clinical presentation is distinctive
• Hyperkeratosis and hyperplasia
• Tumour like warty cauiliflower growths
• Very slow progression
• Uncommon in children (? time or immune)
• Treatment - antifungals / surgery / heat

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Chromo - diagnosis (M4.6)

• Direct microscopy
• Sclerotic bodies (usually easily seen)
• Occasional hyphae
• Culture
• Will grow on most media (some are cyclo R)
• Slow growing (4-6 wks)
• Dark velvety colonies (similar)
• Contamination can be a problem

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Chromo - diagnosis (M4.6b)

• Identification
• Sclerotic cells are identical
• NO dimorphism in vitro
• Complex and variable conidiation
• Hyphael elements are clearly dematiaceous

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Mycetoma (M4.7)

• Terminology
• Eumycetoma if fungal, actinomycetoma if caused by
  an actinomycete.
• Characterised by
• Swollen tumour like body sites with internal
  lesions.
• Draining sinuses, granule formation.
• Epidemiology
• Traumatic implantation, non contagious

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Mycetoma (M4.8)

• Clinical features
• Variable incubation period.
• Swelling hard and painless
• Local spread to contiguous tissue
• Eventual sinus formation and drainage
• Location of lesions linked to exposure
• Male to female is 31
• Therapy is poor for eumycotic but slightly better
  for actinomycotic.

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Mycetoma (M4.9)

• Eumycetoma (dematiaceous and hyaline)
• Madurella mycetomatis
• Pseudallescheria boydii
• Fusarium
• Exophiala jeanselmii
• Actinomycotic (aerobic actinomycetes)
• Actinomadura, Streptomyces, Nocardia
• Actinomycetoma Actinomyces israelii, ANO2 and
  endogenous

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Laboratory diagnosis (M4.10)

• Recover granules black, red, white
• Squash prep microscopy
• 2-6um fungal, lt0.5 actinomycetes
• Culture to cover all
• Use selective for fungi plus selective for
  actinomycetes, but NOT both.
• Dont forget Actinomyces

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Identification of Actinomycetes (M4.11)

• Blood agar, BHI agar, sabs variable
• Typical colonial and microscopic morphology to
  group
• Identification to genus by partial acid fastness,
  but speciation is difficult.

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Summary

• Subcutaneous mycoses
• Sporotrichosis
• Chromoblastomycosis
• Mycetoma
• Eumycotic
• Actinomycotic
• Actinomycosis
• Phaeohyphomycosis
• Hyalohyphomycosis