mycology

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MEDICAL MYCOLOGY
Dr. Vaishali

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MYCOLOGY
Mycology – a branch of Microbiology that
deals with the study of fungi
Characteristics of fungus
• Eukaryotes
• Cell wall contains chitin and mannan
• Cytoplasmic membrane contains sterols
• Divide asexually, sexually or by both
methods
• May be unicellular or multicellular

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CLASSIFICATION OF FUNGI
Morphological classification (Continued…

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Morphological classification …Continues)

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CLASSIFICATION OF FUNGI
Morphologic classification
• Yeast: Unicellular – Cryptococcus
• Yeast-like: Unicellular, forms pseudo
hyphae – Candida
• Filamentous fungi or moulds: Multicellular –
composed of hyphae – Aspergillus
• Dimorphic: Multicellular with hyphae,
filamentous at 22°C and yeast forms at 37°C
– Histoplasma

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CLASSIFICATION OF FUNGI
Systemic classification (Continued…

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Systemic classification
…Continues)

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CLASSIFICATION OF FUNGI
Systemic classification
1. Phycomycetes: Lower fungi, non-septate
hyphae, sporangia with sporangiospores
2. Ascomycetes: Yeast and filamentous fungi
3. Basidiomycetes: Forms sexual spores on
basidium – basidiospores
4. Deuteromycetes or fungi Imperfecti: Sexual
phase not identified – medically important
fungi

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CLASSIFICATION OF FUNGI
Pathogenic classification
• Primarily pathogenic: Causes infection in
healthy individuals – Histoplasma
capsulatum
• Opportunistic pathogens: Causes infection
only in immunosuppressed – Mucor,
Rhizopus

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PATHOGENICITY
• Tissue invasion
– Superficial mycoses
– Cutaneous mycoses
– Subcutaneous OR Deep mycoses
• Mycotoxicosis:
- Aflatoxin and ergotoxin.
• Hypersensitivity (allergic) reaction
– Allergic bronchopulmonary aspergillosis
– Allergic fungal rhino sinusitis

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LABORATORY DIAGNOSIS OF FUNGAL INFECTION
• Specimen collection – from affected site – in
deep infections, blood
• Direct microscopy
– 10% potassium hydroxide (KOH) – skin
scrapings
– Gram stain – Candida
– India ink – Cryptococcus
– Lactophenol cotton blue(LPCB) – hyphae
in fungal culture, tease mount

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LABORATORY DIAGNOSIS OF FUNGAL INFECTION
• Culture
– Sabouraud’s dextrose agar pH 5.4, bird seed
agar,corn meal agar.
– Cycloheximide to prevent contaminant moulds.
– Morphology study in tease mount,
– cellophane mounts or slide culture
• Serology
– Antibody or antigen detection
– Skin tests using antigens
• Molecular methods
– Nucleic acid hybridisation
– Polymerase chain reaction (PCR)

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SDA agar without growth
SDA agar with growth

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ANTI-FUNGAL AGENTS
Anti-fungal agents … Continued)