Fungi by the Tristram scheme M2(-1)

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Fungi by the Tristram scheme M2(-1)
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Overview (M2.0)

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

onychomycosis
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Where are we ?
direct micro
SPECIMEN
CULTURE
identification
microscopy
microscopy
sub culture
special tests
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Tinea versicolour (M2.1)

• Pityriasis versicolour
• Superficial infection of skin caused by
  lipophilic yeast Malassezia furfur
• Older names include Pityrosporum obiculare
• Hypo/hyperpigmented skin lesions
• Asymptomatic - cosmetic
• Reservoir - normal skin flora
• Virulence - unknown trigger of hyphael
  transformation.(sunlight, cell turnover)

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Tinea versicolour (M2.2)

• Diagnosis
• Direct microscopy (large round yeasts, angular
  hyphae)
• Woods lamp - yellow green
• Culture - not necessary (oil overlay)
• Role in other infections?
• Pityrosporal folliculitis
• Seborrheic dermatitis
• Opportunistic sepsis (TPN)

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Tinea nigra (M2.3)

• Phaeoannellomyces werneckii (Exophiala)
• Black yeast - dematiaceous (phaeohyphomycosis)
• Lesions - brown/black scaly
• Plantar / palmar
• Asymptomatic
• Diagnosis - clinical (melanoma)
• Direct microscopy (pigmented septate hyphae)
• Culture
• pale moist yeast like
• Darkens with age (may become more hyphael)

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White piedra (M2.4)

• Trichosporon beigelii - yeast
• Superficial nodular hair infection (nits!)
• Beard, scalp, groin, axilla
• Direct microscopy
• Hyaline hyphae and arthroconidia
• Culture - furry yeast
• Also an opportunistic pathogen
• Disseminated infection
• Cross reactivity with cryptococcal antigen test

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Black piedra (M2.5)

• Piedraia hortae - (dematiaceous)
• Hard black nodules on scalp (?pediculosis)
• Direct microscopy - hyphae,asci and ascospores
• Culture
• Brown to black adherent colonies
• Dark septate hyphae
• Intercalary chlamydoconidia
• Ascospores sometimes.

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Miscellaneous onychomycosis (M2.6)

• Onychomycosis- mainly Candida / dermatophytes.
• Others include
• Scopulariopsis, Acremonium, Aspergillus, Fusarium
• Nails are dirty sites - use selective culture
  (cyclo)
• Problem 1 - tunnel vision cyclohexamide
• Problem 2 - interpretation
• Contaminant or pathogen
• Direct microscopy
• 10 - 20 KOH, extra digestion
• Important detail sometimes present.

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Miscellaneous onychomycosis (M2.7)

• Scopulariopsis
• Brown nails
• Lemon like conidia
• Powdery brown colony
• Resemble Penicillium

• Acremonium
• White nails
• Frond like hyphae
• Feltlike and cottony colony
• Resembles Fusarium