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Mycology Systemic Dimorphic Fungi

Please click audio icon to hear Carol’s narration. Mycology Systemic Dimorphic Fungi. Division of Medical Technology Carol Larson MSEd, MT(ASCP). Click icon for audio. Systemic Dimorphic Fungi. General Characteristics. Growth rate: 2-4 weeks Identification Direct specimen examination

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Mycology Systemic Dimorphic Fungi

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  1. Please click audio icon to hear Carol’s narration MycologySystemic Dimorphic Fungi Division of Medical Technology Carol Larson MSEd, MT(ASCP)

  2. Click icon for audio Systemic Dimorphic Fungi General Characteristics • Growth rate: 2-4 weeks • Identification • Direct specimen examination • Colony morphology • Microscopic morphology • Definitive diagnosis is prove dimorphism • Mycelial stage at 25-30ºC • Yeast / spherule stage in host at 35-37ºC

  3. Click icon for audio Systemic Dimorphic Fungi Epidemiology • Primarily in North America or South America • Found in: • Soil • Decaying vegetation • Bird droppings • Bat droppings

  4. Click icon for audio Systemic Dimorphic Fungi Clinical Significance • Pathogens • Man incidental host • Acquire by inhalation • Develop respiratory infection • Can disseminate and become systemic infection

  5. Click icon for audio Systemic Dimorphic Fungi Clinical Significance • Histoplasmosis • Histoplasma capsulatum • Blastomycosis • Blastomyces dermatitidis • Coccidioidomycosis • Coccidioides immitis • Paracoccidioimycosis • Paracoccidioides brasiliensis

  6. For the systemic dimorphic fungi, what must be demonstrated in the lab to definitively identify them? The systemic dimorphic fungi have two forms (mold and yeast/spherule) and both must be seen in the laboratory either in culture or in direct examination of a specimen.

  7. How are the systemic dimorphic fungal infections acquired? By inhalation of the conidia and fungal elements. The infection begins in the lungs for all of the systemic dimorphic fungi.

  8. Click icon for audio Histoplasmosis • Histoplasma capsulatum • Pathogenesis • 95% of cases are asymptomatic • Infection begins in lung • Invades reticuloendothelial system • Can disseminate (especially in immunocompromised patients)

  9. Click icon for audio Histoplasmosis Laboratory Diagnosis • Specimen • Sputum • Blood • Bone marrow • Urine • Oral lesion scraping • Lymph node biopsy • Liver

  10. Click icon for audio Histoplasmosis Laboratory Diagnosis • Direct detection methods • Giemsa or Wright’s stains • Calcofluor white stain, histological stains • Look for small intracellular yeast cells

  11. Click icon for audio Histoplasmosis Mold - Histoplasma capsulatum • Media • Sab’s and Inhibitory Mold agars • Good growth at 2-4 weeks • Mycosel agar – no growth • Incubate • 25-30ºC • Ambient air • Up to 4-6 weeks

  12. Click icon for audio Histoplasmosis Mold - Histoplasma capsulatum • Colony morphology

  13. Click icon for audio Histoplasmosis Mold - Histoplasma capsulatum • Microscopic morphology

  14. Click icon for audio Histoplasmosis Yeast - Histoplasma capsulatum • Media • Blood enriched media • Incubate at 35ºC in ambient air for 2-4 weeks • Colony morphology • Microscopicmorphology

  15. Click icon for audio Histoplasmosis Serological Testing • Exoantigen test • Immunodiffusion

  16. What is the diagnostic form for Histoplasma capsulatum and what does it look like? The mold phase – its macroconidia are large, round, unicellular, thick-walled and tuberculated.

  17. In patient specimens, where is a common place that you would find Histoplasma capsulatum yeast? Histoplasma capsulatum yeast cells are often found intracellular in mono-nucleated cells.

  18. Click icon for audio Blastomycosis • Blastomyces dermatitidis • Pathogenesis • Acute or chronic suppurative and granulomatous infection • Infection begins in lung • Can disseminate to lungs, bone, soft tissue and skin

  19. Click icon for audio Blastomycosis Laboratory Diagnosis • Specimen • Cutaneous lesions • Sputum • Biopsy of affected organ

  20. Click icon for audio Blastomycosis Laboratory Diagnosis • Direct detection methods • KOH prep • Histological stains • Look for large spherical budding yeast with single bud connected to parent cell by a broad base

  21. Click icon for audio Blastomycosis Mold - Blastomyces dermatitidis • Media • Sab’s and Inhibitory Mold agars • Good growth at 1-4 weeks • Mycosel agar – no growth • Incubate • 25-30ºC • Ambient air • Up to 4-6 weeks

  22. Click icon for audio Blastomycosis Mold - Blastomyces dermatitidis • Colony morphology • Microscopic morphology

  23. Click icon for audio Blastomycosis Yeast - Blastomyces dermatitidis • Media • Cottonseed conversion agar • Incubate at 35ºC in ambient air for 1 week • Colony morphology

  24. Click icon for audio Blastomycosis Yeast - Blastomyces dermatitidis • Microscopic morphology Broad-Based Budding yeast

  25. Click icon for audio Blastomycosis Other Test Methods • Exoantigen test • Immunodiffusion • Nucleic acid amplification assay

  26. What is the diagnostic form for Blastomyces dermatitidis and what does it look like? The yeast phase – it has a broad based single bud and is large in size.

  27. Describe the appearance of the mold form of Blastomyces dermatitidis? The mold form of Blastomyces is very nondescript. It has hyaline, septate hyphae. The conidiophores are short and unbranched and the conidia are hyaline, pyriform, unicellular, terminal, and solitary.

  28. Click icon for audio Coccidioidomycosis • Coccidioides immitis • Pathogenesis • 60% of infections are asymptomatic • Infection begins in lung • Can disseminate (1%) • Southwest U.S. desert area (endemic to San Joaquin Valley)

  29. Click icon for audio Coccidioidomycosis Laboratory Diagnosis • Specimen • Sputum • Biopsy of affected organ

  30. Click icon for audio Coccidioidomycosis Laboratory Diagnosis • Direct detection methods • KOH prep, Calcofluor white stain • Histological stains • Look for spherule • No yeast form

  31. Click icon for audio Coccidioidomycosis Mold - Coccidioides immitis • BIOHAZARD to lab personnel • Media • BAP, Sab’s, Inhibitory Mold, and Mycosel • Good growth at 3 days to 3 weeks • Incubate • 25-30ºC • Ambient air • Up to 4 weeks

  32. Click icon for audio Coccidioidomycosis Mold - Coccidioides immitis • Colony morphology

  33. Click icon for audio Coccidioidomycosis Mold - Coccidioides immitis • Microscopic morphology

  34. Click icon for audio Coccidioidomycosis Spherule - Coccidioides immitis • Not recommended • Media • Special media incubated at 42ºC • Can infect lab animals and do tissue biopsy (experimental)

  35. Click icon for audio Coccidioidomycosis Other Test Methods • Exoantigen test • Immunodiffusion • Nucleic acid amplification assay

  36. What form for Coccidioides immitis is found in patient specimens? The spherule. There is no yeast phase for this fungus.

  37. What does Coccidioides immitis look like when cultured on SAB agar that has been incubated at 30°C? Barrel-shaped alternating arthroconidia.

  38. Click icon for audio Paracoccidioidomycosis • Paracoccidioides brasiliensis • Pathogenesis • Infection begins in lung • Can be asymptomatic and then disseminate to nasal and oral mucosa, gingivae, or conjunctivae • South America (South American Blastomycosis)

  39. Click icon for audio Paracoccidioimycosis Laboratory Diagnosis • Specimen • Sputum • Biopsy of affected organ

  40. Click icon for audio Paracoccidioimycosis Laboratory Diagnosis • Direct detection methods • KOH prep, Calcofluor white stain, and Histological stains • Look for large round or oval, multiple budding yeast cells (“mariner’s wheel”)

  41. Click icon for audio Paracoccidioimycosis Mold - Paracoccidioides brasiliensis • Media • Sab’s and Inhibitory Mold agars • Good growth at 3-4 weeks • Mycosel agar – no growth • Incubate • 25-30ºC • Ambient air • Up to 4-6 weeks

  42. Click icon for audio Paracoccidioimycosis Mold - Paracoccidioides brasiliensis • Colony morphology • Microscopic morphology

  43. Click icon for audio Paracoccidioimycosis Yeast - Paracoccidioides brasiliensis • Media • Blood enriched media • Incubate at 35ºC in ambient air for 4 weeks • Colony morphology • Microscopic morphology

  44. Click icon for audio Paracoccidioimycosis Other Test Methods • Exoantigen test • Immunodiffusion

  45. What is the diagnostic form for Paracoccidioides brasiliensis and what does it look like? The yeast form appears as a large multiple budding yeast that looks like a mariner’s wheel.

  46. Click icon for audio Systemic Dimorphic Fungi In Summary … • Diseases • All begin infection in lungs • Disseminate • Identification • Demonstrate dimorphism • Direct specimen exam • Culture (mold and yeast forms) • Other testing

  47. Who am I? Growth at 25ºC Sputum – silver stain Coccidioides immitis

  48. Who am I? Growth at 25ºC Growth at 35ºC Blastomyces dermatitidis

  49. Who am I? Growth at 25ºC Wright’s stain of blood Histoplasma capsulatum

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