Systemic and opportunistic mycoses - Mycology - MBBS -

Systemic Mycoses &

Opportunistic Mycoses

Objectives of today’s class

To know and understand the Etiology, morphology of Systemic and Oppurtunistic mycoses

To learn about the clinical manifestations, lab diagnosis, treatment, prevention of Systemic and Oppurtunistic mycoses.

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Recap

• Superficial Cutaneous Mycoses includes Tinea nigra, Piedra (White & Black) , Tinea versicolor (Malassezia furfur) and Dermatophytoses (Trichophyton, Microsporum & Epidermophyton)

• Sub-cutaneous or Deep Mycoses includes Mycetoma, Sporotrichosis, Rhinosporidiosis, Phaeohypomycosis & Subcutaneous Zygomycosis.

Introduction to Systemic mycoses

Mostly soil saprophytes Infections - varying degree of severityAsymptomatic – Fatal diseaseThermally dimorphic fungusCaused by Blastomyces spp., Paracoccidioides

spp., Coccidioides spp., & Histoplasma spp.

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Classification of systemic mycosis or dimorphic fungi

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Systemic mycosis

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• Blastomycosis: Blastomyces dermatitidis (Telomorph) Ajellomyces dermatitidis (Perfect state)• Paracoccidioidomycosis: Paracoccidioides brasiliensis• Coccidioidomycosis: Coccidioides immitis• Histoplasmosis: Histoplasma capsulatu m •

Systemic Mycoses (Dimorphic fungi)

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BLASTOMYCOSIS

• Causative agent: Blastomyces dermatitidis• Chronic Suppurative and granulomatous

infections especially of Lungs and Skin• Was seen only in North America, Hence the

name ‘North American Blastomycosis’ .• Recently, Case reports from Africa and India

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BLASTOMYCOSIS

• Pathogenesis: Soil (Source of infection) Inhalation of fungal sporesPrimary infection – mimicks Tuberculosis or

HistoplasmosisAsyptomatic or Lead to focal or diffuse

Consolidation, miliary lesion or abscess formation

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BLASTOMYCOSIS

• Pathogenesis: Disseminated disease – Lungs – Blood –

various part of the bodyHigh fatality rateCutaneous disease – skin of face or other partsManifests as a papule – around which

secondary nodule develop and coalesce – Large elevated ulcerative lesions develop

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BLASTOMYCOSIS

• Laboratory diagnosis: • Samples: Skin, Sputum, Lung biopsy, BAL or

TA, Blood, Body fluids• @ 37 degrees – Budding yeast cell (7-20µm)• @ 25 degrees / RT – Filamentous with septate

hyphae• Older cultures - Chlamydospores

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BLASTOMYCOSIS

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PARACOCCIDIODOMYCOSIS

• Causative agent: Paracoccidioides brasiliensis, Thermally dimorphic fungi.

• Chronic granulomatous diseases of skin, lymph nodes & Internal organs

• Confined to South America (South American Blastomycosis)

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PARACOCCIDIODOMYCOSIS• Pathogenesis: • Inhalation of spores – Primary infection• Hematogenous spread – Mucosa of nose,

mouth, GIT & Lymphatics • Prominent feature: Ulcerative granuloma of

nasal and buccal mucosa

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PARACOCCIDIODOMYCOSIS• Lab diagnosis: • @ 25 degrees / RT – Hyphal forms• @ 37 degrees – Budding yeast cell –

Large globose or oval cells with multiple buds encircling mother cell (Mariner’s wheel or Pilot’s wheel appearance)

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PARACOCCIDIODOMYCOSIS

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COCCIDIOIDOMYCOSIS

• Primary pulmonary infection• Inapparent or benign or severe or fatal• Endemic in Dry arid regions of Southwestern

USA• Source: Fungus in soil and in rodents• Causative agent: Coccidioides immitis

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COCCIDIOIDOMYCOSIS

• Pathogenesis: • Inhalation of dust containing arthrospores • Mostly Asymptomatic with life-long immunity• Self limiting influenza like fever (Desert

rheumatism or Valley fever)• <1% develop Chronic progressive

disseminated disease (Coccidioidal granuloma) – Highly fatal disease

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COCCIDIOIDOMYCOSIS

• Lab diagnosis: Thermally dimorphic fungus- @ 37 degrees – Budding yeast cell and @ RT – Hyphal forms, Spherule is filled with endospores

• Mycelial phase has hyphae which fragments into highly infectious arthrospores

• DNA probe test or Exoantigen testing done in Biosafety cabinet is preferred to culture

• Skin test: Delayed hypersensitivity (Coccidioidin test) 12/17/15 19

COCCIDIOIDOMYCOSIS Arthrospores

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COCCIDIOIDOMYCOSIS

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HISTOPLASMOSIS

• Intracellular infection of reticuloendothelial system

• Histoplasmosis - Histoplasma capsulatum var. capsulatum

• African Histoplasmosis – Histoplasma capsulatum var. duboisii

• 1905 – Darling ascribed Leishmania donovani (Hemoflagellate parasite) as the cause

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HISTOPLASMOSIS

• Worldwide but common in USA• Endemic in central and eastern states• Source: soil, rotting trees and bird feces• Classical disease –asymptomatic and heal

spontaneously• Miliary, pulmonary lesions resembling TB• Disseminated disease occurs in few

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HISTOPLASMOSIS• Lab diagnosis:• Thermally dimorphic fungus• SDA – White cottony mycelial growth at 37

degrees, Tuberculate spores at 25 degrees• Microscopy with Giemsa or Wright stain of

blood, bone marrow, lymph node biopsy or skin lesions

• Serology – Histoplasmin antigen test (DTH)

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HISTOPLASMOSIS

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TREATMENT

• Oral Itraconazole 50-100 mg/day – drug of choice for Paracoccidiodomycosis

• Fluconazole – drug of choice for Coccidioidal meningitis

• Amphotericin B - drug of choice for Invasive Histoplasmosis

• Oral imidazoles (Fluconazole, Itraconazole, Ketoconazole & Voriconazole) for less severe infections

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Summary and Take home message

• Systemic mycoses • Thermally dimorphic fungi• Granulomatous lesions are common• Could be even fatal• Culture, Microscopy, DNA probe test and

antigen tests can be used for diagnosis

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THANK YOU

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Opportunistic Mycoses

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Miscellaneous mycoses

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