05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Classification, Lab diagnosis

and Important diseases caused

by Fungi

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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ObjectivesTo know about important characteristics of fungi

To know various classification systems

To know medically important fungi

To know the lab diagnosis of fungi

To know treatment of fungal diseases

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Mycology• Study of fungi – mycology

• Mykos – mushroom

• All fungi are eukaryotic

• Natural habitat- soil, water and decaying organic debris

• Obligate or facultative aerobe

• Chemotrophic organisms

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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• Differences from bacteria

– Posses rigid cell wall

– Contain chitin, mannan and polysacharide

– Cytopalsmic membrane contain sterols

– True nuclei with Nuclear membrane, mitochondria and endopalsmic reticulum

– Unicellular or multicellular

– Divide by asexually, sexually or by both

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Classification

A. Taxanomic classification

Phyllum Thallophyta Four calsses of fungi

B. Morphological classification

Yeasts Yeasts like fungi Moulds Dimorphic fungi

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Thallophyta

ThallophytaIrregular plant masses lacking definite root, stem and leaf structures

Fungi Algae

(No chlorophyll) (Chlorophyll)

4 classes

Zygomycetes Ascomycetes Basidiomycetes Deuteromycetes or fungi imperfecti

• Lower fungi having non-septate hyphae• Forms asexual spores sporangiospores• Sexual spores zygospores and oospres

• Septate hyphae• Sexual spores (ascospores) are present within the sac or ascus

• Septate hyphae•Sexual spores are basidiospores on a basidium

• Septate hyphae•Lack a known sexual state. Most fungi medically important fungi belongs to this class

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Yeasts

i. Round to oval unicelluarii. Reproduce by buddingiii. Creamy mucoid coloniesiv. E.g. Cryptococcus neoformans

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Yeasts like fungi

• Partly as yeasts and partly as elongated budding cells

• Germ tube to demonstrate pseudohyphae

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Moulds

1. Grow as branching filaments – hyphae

2. Hyphae septate or nonseptate

3. Continue growth called as mycelium

4. E.g Dermatophytes, Aspergillus, Penicillium and Rhizophus

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Dimorphic fungi

• They exists as yeasts in host tissue and in cultures as mycelial growth

• Blastomyces dermatitidis, Paracoccidioides, Coccidiodes immitis, Histoplasma, Sporothrix

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Reproduction and sporulation• Sexual spores – oospres, ascospores,

zygospores and basidiospores• Vegetative spores – – Blastospores:formed by budding from parent cell

– Arthrospores: cross septa into hyphae

• Aerial spores: Conidiospores, Microconidia, Macroconidia, Sporangiospores

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Laboratory Diagnosis

A. Direct microscopy– KOH preparation– Gram staining– India ink preparation

B. Culture- SDA

C. Slide culture test

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Classification of fungal diseases

A. Superficial mycoses- skin nails hair

B. Subcutaneous mycoses – myetoma

C. Systemic mycoses - aspergillosis

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Dermatophytes

• They infect superficial keratinized tissue (skin, nail and hair) without involving tissue

• They break down and utilizes keratin• Incapabale of penetrating subcutaneous tissue• Cause dermatomycoses also known as

ringworm

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Cylindrical macroconidia

Fusiform macroconidia

Club shaped macroconidia

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Classification

– Trichophyton - hair, skin and nail

– Microsporum – hair , skin

– Epidermophyton – skin and nail

Lab diagnosis:

Specimen: skin, hair or nail Direct microscopy – LPCB mount Culture

Treatment

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Subcutaneous Mycoses• Mycetoma : crhonic granulomatous infection of

subcutaneous tissue usually affects foot• Also known as Madura foot• Mainly in tropical countirs• Common in Tamilnadu• Caused by Actinomycetes and filamentous fungi• Enter through minor trauma• Diagnosis made by observing granules• Treatment- sulphonamides sometime amputation

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Sporotrichosis• Is nodular, ulcerating disease of skin and subcutaneous

tissue• Acces through thorn pricks or injuries• Spread through lymphatics upto regional lymph nodes • Sporothrix schenckii – dimorphic fungi• Lab diagnosis by culture

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Rhinosporidiosis• Is a chronic granulomatous disease characterized by

formation of friable polyps, usually confined to nose, mouth or eye

• Causative agent Rhinosporidium seeberi• Reported from Srilanka and India• Mode of infection is not known• Lab diagnosis done by demonstration of sporangia

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Rhinosporidiosis

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Systemic mycoses1. Histoplasmosis– Histoplasma capsulatum– Reticuloendothelial system– Source – soil with excreta of birds– Asymptomatic– Sputum, bone marrow, blood, scrapings,

biopsies– Geimsa stain or Wright stain– Culture- SDA– Amphotericin B

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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2. Blastomycosis

– Blastomyces dermatitidis- dimorphic fungi

– Infection mainly to skin, bone and genitourinary tract

– Inhalation of conidia

– Asymptomatic

– Sputum, pus or scrapings

– 10% KOH, H&E stain and PAS stain

– Culture-SDA

– Amphotericin B

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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3. Paracoccidiomycosis– Paracoccidioides brasilensis- dimorphic fungi– Inhalation of spores– Same

4. Coccidiodomycosis

5. Crptococcosis- Crptococcus neoformans- Inhalation of dust- Seen in immunocompromised- demosntration of capsule by india ink

6. Opportunistic mycoses- candiasis, aspergillosis, zygomycoses

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Aspergillus fumigatus

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Aspergillus terreus

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Aspergillus fumigatus

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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ASpergillus niger

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Typical growth of Aspergillus spp

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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ASpergillus flavus

05/02/2023 Mohammad Mukhit Kazi, Lecturer SDCH Pune

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Mucor

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Take home message

• Fungi are eukaryotes

• Medically important fungi belongs to Fungi imperfecti or Deuteromycetes

• Sabourauds dextrose agar is used to culture

• Slide culture to demonstrate better morphological characters

• KOH mount or LPCB mount for demonstration

• Mainly opportunistic infections

• E.g. Candidiasis, Cryptococcosis, Aspergillosis