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Respiratory mycoses (reduced version)

Respiratory mycoses (reduced version). Dr Elizabeth M. Johnson, Director HPA Mycology Reference Laboratory, Bristol. Kingdom Fungi. Eucaryotic organisms No chlorophyll Absorb nourishment from living or dead organic material Filamentous form: septate or aseptate hyphae

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Respiratory mycoses (reduced version)

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  1. Respiratory mycoses(reduced version) Dr Elizabeth M. Johnson, Director HPA Mycology Reference Laboratory, Bristol

  2. Kingdom Fungi • Eucaryotic organisms • No chlorophyll • Absorb nourishment from living or dead organic material • Filamentous form: septate or aseptate hyphae • Yeasts: unicellular fungi • Sexual and asexual forms

  3. Inhalation of fungal spores DISEASE SPECTRUM ALLERGY Spores 8 µm SINUSITIS ASPERGILLOMA PULMONARYASPERGILLOSIS 2-4 µm DISEMINATED ASPERGILLOSIS

  4. Schizophyllum commune • Basidiomycete often found on rotting wood • Increasingly recognised as a cause of sinusitis • Produces raised fruiting bodies on prolonged incubation • Look for clamp connections and spicules

  5. Diagnosis of respiratory mycoses Presence of risk factors Clinical signs Laboratory Microscopy & Culture of sputum and BAL Serology - detection of antibodies and fungal antigens Detection of fungal DNA using PCR

  6. Patchy changes seen on chest radiograph of patient with invasive aspergillosis

  7. Aspergillosis: radiological findingsin the lungs Halo sign on CT scan - early finding (1-10 days) Crescent-shaped lesions on chest radiograph - late sign following neutrophil recovery Air crescent Halo sign

  8. Aspergillus hyphae in a sputum sample Microscopy of a mucoraceous mould

  9. Absidia corymbifera

  10. Fungal serology - Antigens Tests for antigenaemia Asp Cryp • Latex agglutination + +++ • ELISA + +++ Aspergillus ELISARat EBA-2 monoclonal antibodydirected against galactomannansensitivity - 1 ng/ml G - testAmebocyte limulus lysate test Horse shoe crab coagulation cascadesensitivity - 1 pg/ml • TARGET • Cell wall components: • mannans • galactomannan • 1,3 beta-D-glucans • Cytoplasmic antigens • Metabolites

  11. Pitfalls of PCR Choice of sampleBlood, Serum or PlasmaBALTissue Method of DNA extractionMechanicalChemicalEnzymes Contamination:Environmental Amplicon Absence of standardization of reagents and targets

  12. Infection with Scedosporium spp. • Pseudallesheriosis - sexual form (teleomorph) Pseudallescheria boydii • Clinically indistinguishable from invasive aspergillosis • Specific features: • Infection often follows near-drowning accidents • Neutropenia is a risk factor • Refractory to treatment

  13. Scedosporium apiospermum Scedosporium prolificans

  14. Infection with Fusarium spp. • Clinically very similar to invasive aspergillosis • Specific features: • Cutaneous lesions (70%) • Blood culture often positive (50-70%) • Often water borne • Sinus infection may lead to disseminated disease

  15. Fusarium solani

  16. Cryptococcosis in the UK 1980 - 1999 Knight et al. 1993 J Infect 27:185-191 No. cases Year AIDS-defining 24 18 24 illness

  17. Cryptococcus neoformans • CAN infect healthy, non-immunocompromised hosts • Today mainly associated with HIV-infected patients • AIDS-defining illness • HAART has had an impact • Mode of infection is inhalation but haematogenous dissemination leads to meningitis • Diagnosis by direct microscopy or LPA antigen test

  18. Indian ink stain of Cryptococcus neoformans

  19. Pneumocystis carinii var. hominis= Pneumocystis jiroveci

  20. Coccidioides immitis Cause of coccidioidomycosis Endemic areas southwestern USA, Central and South America Infection by inhalation of arthroconidia Mild transient pulmonary infection 1% develop disseminated disease

  21. Coccidioides immitis distribution Endemic areas: southwestern USA Central and South America From: Medical Mycology Kwon-Chung and Bennett 1992 Lea & Febiger

  22. Coccidioides immitis life cycle From: Medical Mycology Kwon-Chung and Bennett 1992 Lea & Febiger

  23. Direct microscopy Endosporulating spherules seen on direct microscopy of pus, sputum or joint fluid Difficult to obtain in culture Culture Mycelial colonies after incubation at 25 - 30ºC for 2-7 days Growth on actidione Typical arthroconidia Exoantigen test to confirm Gene-probe also available Laboratory diagnosis of coccidioidomycosis Serology Immunodiffusion and complement fixation

  24. Histoplasmosis • Guano-enriched soil source • Tissue form: budding yeasts • Reticuloendothelial system • Chronic cases - calcifications • Widespread geographically - especially Eastern USA, & Africa • Histoplasma var. capsulatum and var. duboisii

  25. Histoplasmosis

  26. Laboratory diagnosis of histoplasmosis • Culture • Mycelial colonies after • incubation at 25 - 30ºC • for 2-7 days • Conversion to yeast on • blood agar or BHI agar at • 37ºC, 2-6 weeks • Direct microscopy • Small, oval, budding yeast • cells seen in Giemsa • stained smears • Cells often seen within • macrophages Serology Immunodiffusion and complement fixation

  27. The ideal diagnostic test • Sensitive and specific • High positive predictive value • High negative predictive value • Simple, rapid and inexpensive

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