Lesson 1

• -study of fungi

  Mycology
• -Aerobic

  -Eukaryotic

  -Saprophytic

  -Achlorophyllous

  -Chemoheterotrophic

  -Cell wall

  -Cell Membrane: Sterol (ergosterol)

  
  

  General Characteristic of Fungi
• -Yeast vs Mold

  Morphology
• -Unicellular

  -Tissue Form

  -produce a progeny (daughter) cell

  -Produce buds - blastoconidia

  -Pseudo-hyphae - attached in achain which can resemble a string of pearls


  Yeast
• -multicellular

  -environmental form

  -Basic structures (hyphae and spores)

  -Reproduction (sexual or asexual spores)

  Mold
• -Hyphae

  -Spores


  Basic Structures of Molds
• -apical extension

  Hyphae
• -Septate - frequent cross walls

  -Aseptate/Sparsely septate/Coenocytic - no cross walls/few cross walls


  Septate vs Coenocytic Hyphae
• -Dematiaceous - darkly pigmented

  -Hyaline - lightly pigmented


  Dematiaceous vs Hyaline Hyphae
• -responsible for fungal reproduction

  Spores
• -single parent cell

  -Anamorph (e.g. Histoplasma capsulatum)

  Asexual Spores
• -containing structure known as sporangium

  -Mucorales


  Sporangiospores
• -borne naked on specialized structures

  Conidia
• -rectangular spore formed when a septate hypha fragments

  Arthrospore
• -spherical conidium


  Chlamydospore
• -vase-shaped cell called a phialide or sterigma


  Phialospore
• -budding or pinching off from a parent cell

  Blastospore
• -small and large conidia formed by the same fungus under varying conditions

  Macroconidia and Microconidia
• -two parental nuclei

  -Teleomorph (e.g. Ajellomyces capsulatum)


  Sexual Spores
• -diploid structures formed when hyphae of two strains (+ and - strains) fuse


  Zygospores
• -spores produced inside a special fungal sac known as an ascus

  -formed when different strains or sexes join and produce an offspring of terminal cell called dikaryons

  Ascospores
• -club-shaped cell know as basidium


  Basidiospores
• -ability to exist in either yeast or mold form

  -Exemplified by fungi causing systematic mycoses

  -mold in the cold, yeast in the beast

  Dimorphism
• 1. Yeast vs Mold
  2. Molds: Type of Hyphae
  3. Asexual Reproduction
  4. Sexual Reproduction - Taxonomy
  5. Type of Disease Caused (Mycoses) - Clinical


  Classification of Fungi
• -Zygomycota (conjugation fungi)

  -Ascomycota (sac fungi)

  -Basidiomycota (club fungi)

  -Deuteromycota (fungi imperfect)


  Taxonomical Classification of Fungi
• -1,000 species

  -Sexual reproduction: zygospores/zygotes

  -Asexual reproduction: Sporangiospores

  -Hyphae: coenocytic

  
  

  Zygomycota (conjugation fungi)
• -Entomopthorales

  -Mucorales


  clinically important species of Zygomycota
• -32,000 species

  -Sexual reproduction: Ascospores/asci/ascocarps

  -Asexual reproduction: conidia


  Ascomycota (sac fungi)
• -Ajellomyces

  -Candida


  Clinically Important Species of Ascomycota
• -22,000 species

  -Sexual reproduction: basidiospores/basidium

  -Asexual reproduction: with or without conidia


  Basidiomycota (club fungi)
• -Malassezia, Trichosporon

  -Cryptococcus


  Clinically important species of Basidiomycota
• -mitosporic fungi - has no sexual reproductive cycle

  -assigned artificial classes (form of growth and asexual reproduction)

  Deuteromycota (fungi imperfect)
• -hyphae or on special hyphal branches called conidiophores


  Hyphomycetes
• -spherical with an apical opening, flat and cup shaped

  -few are clinically important

  Coelomycetes
• -Asexual reproduction: Loose, budding, single cell (blastospores/blastoconidia), may appear as pseudohyphae/pseudomycelium

  -no hyphae

  -candida

  Blastomycetes
• -Teleomorph - Sexual stage

  -Anamorph - Asexual stage

  -Holomorph - fungus as a whole, encompassing both teleomorph and anamorph stage


  Nomenclature
• -According to genus name of the causative agent; Aspergillosis, Candidiasis, Sporotrichosis ; problematic when the name of the organism changes

  -Pathology X due to fungus Y

  -According to classification/type of fungi causing disease; (Hyalohyphomycosis and Phaeohyphomycosis)


  Naming Fungal Diseases (Mycoses)
• 1. Superficial Mycoses - outermost layer of skin, hair
  2. Cutaneous Mycoses - keratinized layer of skin, hair and nails
  3. Subcutaneous Mycoses - deeper layers of the skin, cornea, muscle, connective tissue
  4. Endemic/Systemic Mycoses - caused by dimorphic fungi; primary infection in the lungs
  5. Opportunistic Mycoses - caused by fungi normally found as human commensals


  Classification of Mycoses