Medical Mycology

1. Classification,
Lab diagnosis
and
Important diseases caused
by
Fungi
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

2. 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
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

3. 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
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

4. • 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
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

5. Classification
A. Taxanomic classification
 Phyllum Thallophyta
 Four calsses of fungi
B. Morphological classification
 Yeasts
 Yeasts like fungi
 Moulds
 Dimorphic fungi
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

6. 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
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

7. Yeasts
i. Round to oval unicelluar
ii. Reproduce by budding
iii. Creamy mucoid colonies
iv. E.g. Cryptococcus neoformans
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

8. Yeasts like fungi
• Partly as yeasts and partly as elongated
budding cells
• Germ tube to demonstrate pseudohyphae
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

9. 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
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

10. Dimorphic fungi
• They exists as yeasts in host tissue and in
cultures as mycelial growth
• Blastomyces dermatitidis, Paracoccidioides,
Coccidiodes immitis, Histoplasma, Sporothrix
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

11. 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
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

12. Laboratory Diagnosis
A. Direct microscopy
– KOH preparation
– Gram staining
– India ink preparation
B. Culture
- SDA
C. Slide culture test
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

13. Classification of fungal diseases
A. Superficial mycoses- skin nails hair
B. Subcutaneous mycoses – myetoma
C. Systemic mycoses - aspergillosis
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

14. 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
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

15. Cylindrical
macroconidia
Fusiform
macroconidia
Club shaped
macroconidia
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

17. 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
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

18. 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
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

19. 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
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

20. 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
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

21. Rhinosporidiosis
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

22. 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 B
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

23. 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
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

24. 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
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

25. Aspergillus fumigatus
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Pune

26. Aspergillus terreus
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Pune

27. Aspergillus fumigatus
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Pune

28. ASpergillus niger
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Pune

29. Typical growth of Aspergillus spp
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

30. ASpergillus flavus
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

31. Mucor
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune

32. 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
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Mohammad Mukhit Kazi, Lecturer SDCH
Pune