Medical mycology
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Transcript of Medical mycology
Classification, Lab diagnosis
and Important diseases caused
by Fungi
2/13/2015 1Mohammad Mukhit Kazi, Lecturer SDCH
Pune
Objectives
To 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
2/13/2015 2Mohammad Mukhit Kazi, Lecturer SDCH
Pune
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
2/13/2015 3Mohammad Mukhit Kazi, Lecturer SDCH
Pune
• 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
2/13/2015 4Mohammad Mukhit Kazi, Lecturer SDCH
Pune
Classification
A. Taxanomic classification
Phyllum Thallophyta
Four calsses of fungi
B. Morphological classification
Yeasts
Yeasts like fungi
Moulds
Dimorphic fungi
2/13/2015 5Mohammad Mukhit Kazi, Lecturer SDCH
Pune
Thallophyta
Thallophyta
Irregular 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
2/13/2015 6Mohammad Mukhit Kazi, Lecturer SDCH
Pune
Yeasts
i. Round to oval unicelluar
ii. Reproduce by budding
iii. Creamy mucoid colonies
iv. E.g. Cryptococcus neoformans
2/13/2015 7Mohammad Mukhit Kazi, Lecturer SDCH
Pune
Yeasts like fungi
• Partly as yeasts and partly as elongated budding cells
• Germ tube to demonstrate pseudohyphae
2/13/2015 8Mohammad Mukhit Kazi, Lecturer SDCH
Pune
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
2/13/2015 9Mohammad Mukhit Kazi, Lecturer SDCH
Pune
Dimorphic fungi
• They exists as yeasts in host tissue and in cultures as mycelial growth
• Blastomyces dermatitidis, Paracoccidioides, Coccidiodes immitis, Histoplasma, Sporothrix
2/13/2015 10Mohammad Mukhit Kazi, Lecturer SDCH
Pune
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
2/13/2015 11Mohammad Mukhit Kazi, Lecturer SDCH
Pune
Laboratory Diagnosis
A. Direct microscopy
– KOH preparation
– Gram staining
– India ink preparation
B. Culture
- SDA
C. Slide culture test
2/13/2015 12Mohammad Mukhit Kazi, Lecturer SDCH
Pune
Classification of fungal diseases
A. Superficial mycoses- skin nails hair
B. Subcutaneous mycoses – myetoma
C. Systemic mycoses - aspergillosis
2/13/2015 13Mohammad Mukhit Kazi, Lecturer SDCH
Pune
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
2/13/2015 14Mohammad Mukhit Kazi, Lecturer SDCH
Pune
Cylindrical macroconidia
Fusiform macroconidia
Club shaped macroconidia
2/13/2015 15Mohammad Mukhit Kazi, Lecturer SDCH
Pune
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
2/13/2015 17Mohammad Mukhit Kazi, Lecturer SDCH
Pune
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
2/13/2015 18Mohammad Mukhit Kazi, Lecturer SDCH
Pune
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
2/13/2015 19Mohammad Mukhit Kazi, Lecturer SDCH
Pune
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
2/13/2015 20Mohammad Mukhit Kazi, Lecturer SDCH
Pune
Systemic mycoses
1. 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 B2/13/2015 22
Mohammad Mukhit Kazi, Lecturer SDCH Pune
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
2/13/2015 23Mohammad Mukhit Kazi, Lecturer SDCH
Pune
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
2/13/2015 24Mohammad Mukhit Kazi, Lecturer SDCH
Pune
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
2/13/2015 32Mohammad Mukhit Kazi, Lecturer SDCH
Pune