Dimorphic fungi

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Dimorphic fungi
2013-12-10 19:14:13
Dimorphic fungi

Dirmorphic fungi
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  1. What are common infections & transmission for dirmorphic fungi except S. shenckii
    • Pulmonary infections
    • Common cold or flu symptoms
    • granulomatous lesions in lungs

    Transmitted via *Respiratory route
  2. S. shenckii infectious symptoms and location
    • Cutaneous or subcutaneous
    • Ulcers and abcesses along lymphatic channels

    *Rose Gardner Disease

    Worldwide - Soil Saprobe
  3. Sporothrix shenckii lab ident
    Tissue or pus used

    • Macro:
    • 3-5 days both yeast (at 37C) & Mould (at 25C) produce growth

    • Mould: Mature colonies are dark and flat
    • Yeast: White or tan


    • Mould: delicate thin septate hyphae, freqently found as ropes,. Conidiophores produce multiple conidia in flowerette arrangements.
    • 2 types of conidia - small unicellular or large dark walled spheres.
    • Yeast: cigar shaped at 37C
  4. Blastomyces dermatitidis

    Mississippi & Ohio River Valley

    Soil Saprobe  - found in wood, rotting vegetation, & river banks

    Chronic granulomatous disease affecting lungs, skin, & mucous membranes

    Chronic cutaneous blastomycosis - ulcerated lesions

    Systemic blastomycosis - bone lesions, osteomyelitis are common * any organ
  5. *see pic taken on ipad for dimorphic fungi*
    *see pic taken on ipad for dimorphic fungi*
  6. Blastomyces dermatitidis lab ident
    *Sputum, aspirate, skin scraping, blood, urine, & CSF (csf if systemic)

    • MACRO:
    • 25C - Mould - SLOW - white to beighe waxy 
    • MICRO:
    • Mould - Fine septate hyaline hyphae
    • Conidia directly on hyphae or on lateral conidiophores

    • MACRO:
    • Yeast - 37C - 10-15 days - on enriched media
    • MICRO:
    • Hyaline, large, & budding
  7. Coccidioides immitis

    Location and disease
    • SW US & Northern Mexico (hot, semi arid climates)
    • Causes Valley Fever

    Saprobe in mould form (desert soil)

    **Occupational hazard

    Primary pulmonary coccidiomycosis

    May be asymptomatic and self limiting
  8. Coccidioides immitis lab indent.
    **YEAST form not found in lab**

    • Macro:
    • 3-5 days on SDA/SABHI
    • Whtie and cottony (cobwebs)

    Arthroconidia appear in 7-10days

    • Micro:
    • Hyaline septate hyphae
    • Wide barrel shaped arthrodinidia **DISJUNCTURE CELLS

  9. Histoplasma capsulatum 

    Location & Disease
    • Worldwid - 
    • Mississippi & Ohio River Valley

    Chicken, bird, & bat guano

    Occupational hazard

    • Causes: Histoplasmosis: chronic granulomatous lung disease
    • *fatal in 5% of cases & usually in children

    Organism found in macrophages*
  10. Histoplasma capsulatum Lab ident.
    • Macro Mould: 
    • SLOW, Tan & fluffy

    • Micro Mould:
    • Fine septate hyphae, micro and macroconidia
    • Macro become tuberculate with age

    • Macro Yeast: 
    • 10-15 days on enriched media (BHI or SABI)
    • Micro Yeast:
    • Cells bud at narrow neck
  11. Paracoccidioides brasiliensis

    Location & Disease
    South AMerica, Central American and Southern Mexico

    Prefers Acidic soil 

    • Causes paracoccidioidomycosis:
    • ~asymtomatic & self limiting
    • ~Can disseminate to other tissues
    • ~can cause cutaneous diseast
  12. Paracoccidioides brasiliensis Lab Ident
    • Macro Mould:
    • 2-3 weeks
    • Flat & White
    • Micro Mould:
    • Fine hyaline septate hyphae
    • Conididation is absent on modified SDA

    • Macro Yeast:
    • Will grow on enriched media t 37C
    • Micro Yeast:
    • Multiple thin necked buds (*mariners wheel)