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INTRODUCTION TO MYCOLOGY By Dr. Emad AbdElhameed Morad Lecturer of Medical Microbiology and Immunology Fungi are eukaryotic organisms. Their cell wall consists of chitin. – PowerPoint PPT presentation

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Title: Beveled Slide Style


1
INTRODUCTION TO MYCOLOGY
By
Dr. Emad AbdElhameed Morad
Lecturer of Medical Microbiology and Immunology
2
  • Fungi are eukaryotic organisms.
  • Their cell wall consists of chitin.
  • Their cell membrane contains ergosterol.

Eukaryotes (Fungi) Prokaryotes (Bacteria)
10-100 um 0.1-10 um
Nuclear membrane No nuclear membrane
multiple Single chromosome
Histones No histones
Mitotic division Binary fission
Organelles No organelles
Chitin Peptidoglycan
Ergosterol No ergosterol
80 S ribosomes 70 S ribosomes
3
  • Classification

4
Morphological
Clinical
Systematic
5
Fungal morphology
Yeast
Mold
Dimorphic
6
  • Oval or round cells that reproduce by budding to
    form blastospores.
  • May form pseudohyphae (if blastospores remain
    attached to each other).
  • Examples Candida, Cryptococcus.

Yeasts
7
Budding yeast cells
Pseudohyphae
8
  • Also called filamentous fungi or mycelial fungi.
  • Formed of filaments called hyphae.
  • Hyphae interlace to form mycelium.
  • Hyphae may be septate or aseptate.
  • Reproduce by formation of conidia.
  • Conidia may be unicellular (microconidia) or
    multicellular (macroconidia).
  • Examples are dermatophytes aspergillus.

Molds
9

Hyphae
Mycelium
Microconidia
Macroconidia
10
  • These fungi occur in two forms
  • At the room temperature (22 degree), it appears
    as mold.
  • In the body (37 degree), it appears as yeast
    cells.
  • Examples Histoplasma Blastomyces.

Dimorphic fungi
At 22 degree
At 37 degree
11
Clinical classification
Superficial mycoses
Cutaneous mycoses
Subcutaneous mycoses
Systemic mycoses
Opportunistic mycoses
Allergy mycetismus mycotoxicosis
12
  • Fungal infections confined to the stratum corneum
    without tissue invasion.
  • Example Tinea versicolor caused by Malassezia
    furfur.

Superficial mycoses
13
  • Fungal infections that involve keratinized
    tissues as skin, hair, nail.
  • Example Tinea caused by dermatophytes.

Cutaneous mycoses
14
  • Fungal infections that are confined to
    subcutaneous tissues without dissemination to
    distant sites.
  • Example mycetoma (madura foot).

Subcutaneous mycoses
15
  • Also called endemic mycoses.
  • Begin as primary pulmonary lesions that may
    disseminate to any organ.
  • Caused by dimorphic fungi.

Systemic mycoses
16
  • Affect immunocompromised individuals
  • Examples are
  • Candidiasis caused by Candida albicans.
  • Cryptococcosis caused by Cryptococcus
    neoformans.
  • Aspergillosis caused by aspergillus fungus.
  • Pneumocystis pneumonia caused by pneumocystis
    jiroveci in AIDS patients.

Opportunistic mycoses
17
  • Allergy occurs to fungal spores particularly
    those of aspergillus fungus.
  • Example bronchial asthma.
  • The fungal flesh itself is toxic.
  • Example Amanita mushroom poisoning.

Allergy
Mycetismus
18
  • Example Aflatoxins produced by Aspergillus
    flavus which infects grains and peanuts. This
    toxin is hepatotoxic and cause tumors in animals
    and suspected of causing hepatic carcinoma in
    humans.

Mycotoxicosis
19
  • It is based on the type of fungal spores
  • Sexual spores
  • Asexual spores

Systematic classification
20
Sexual spores
  • Zygospores
  • Fungi forming zygospores are called zygomycetes.
  • Ascospores
  • Ascospores are carried in ascus.
  • Fungi forming ascospores are called ascomycetes.
  • Basidiospores
  • Basidiospores are carried on basidium.
  • Fungi forming basidiospores are called
    basidiomycetes.

Deuteromycetes are fungi whose sexual spores are
unknown. But, they produce asexual spores.
21
Zygospores
Ascospores
Basidiospores
22
Asexual spores
  • Blastospores
  • Produced by budding of the yeast cells.
  • Conidia
  • Produced by molds.
  • May be microconidia or macroconidia.
  • Arthrospores
  • Produced by fragmentation of hyphae.
  • Chlamydospores
  • Rounded thick walled spores produced by candida
    fungus.

23
Blastospores
Microconidia
Macroconidia
Arthrospores
Chlamydospores
24
Antifungal drugs
  • Selective toxicity is very limited in antifungal
    drugs because fungi like human cells are
    eukaryotic.
  • They are
  • Amphotericin B
  • Binds to the ergosterol in the fungal cell
    membrane.
  • Used in severe fungal infections.
  • Nephrotoxic.
  • Flucytosine
  • Inhibit fungal DNA synthesis.

25
  • Azoles
  • Like ketoconazle, fluconazole, itraconazole.
  • Inhibit ergosterol synthesis.
  • Terbinafine
  • Inhibit ergosterol synthesis.
  • Used in treatment of dermatophytes.
  • Griseofulvin
  • Used in treatment of dermatophytes because it is
    concentrated in the keratinized tissues.
  • Topical antifungal agents
  • Nystatin.
  • Clotrimazole and miconazole.

26
  • Caspofungin
  • New antifungal drug
  • Inhibit fungal cell wall chitin synthesis
  • Used in invasive fungal infections

27

GOOD LUCK
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