Mycology PRELIMS

• Study of pathogenic fungi
• Yeast


  Unicellular fungi, Catalase-positive, Microscopic appearance: Unicellular, spherical or ellipsoid shape, average size of 2-60 um
• Colony morphology: Different textures and appearances used as an initial way to identify fungi
• Stains used for pigmented hyphae: Gomori methenamine silver nitrate stain (Dematiaceous appears black, Hyaline appears colorless), Fontana masson (Dematiaceous appears brown, Hyaline appears pink to red)
• Different types of hyphae based on pigmentation

  • Hyaline Hyphae (moniliaceous): Either non-pigmented, clear, colorless, or lightly pigmented (e.g., Fusarium species)
  • Dematiaceous Hyphae: Highly pigmented due to melanin in the cell wall (e.g., Exophiala species)
• Cryptococcus neoformans is not normal flora in the body, isolated from bird excreta, and causes fungemia (presence of fungi in the blood)
• General characteristics of fungi and bacteria

  • Cell structure: Eukaryotic (fungi), Prokaryotic (bacteria)
  • Size: >5 um (fungi), <5 um (bacteria)
  • Cell wall composition: Glucan, chitin, mannan, and other polysaccharides (fungi), Muramic acid/peptidoglycan (bacteria)
  • Cytoplasmic membrane: Sterols (ergosterol) present in fungi, No sterols in bacteria
  • Cytoplasmic contents: Includes mitochondria and ER in fungi, No mitochondria and ER in bacteria
  • Spores: Sexual and asexual spores in fungi, Endospores for some bacteria
  • Mode of reproduction: Either sexual or asexual in fungi, Binary fission in bacteria
  • Thermal dimorphism: Yes (some) and monomorphic in fungi, No/monomorphic only in bacteria
  • Metabolism: Organotrophs/chemoheterotrophs in fungi, Many bacteria do not require carbon
  • Gas growth requirements: Obligate aerobe and facultative anaerobe in fungi, Many bacteria are obligate anaerobe, obligate aerobe, facultative anaerobe, and microaerophilic
• Molds/Moulds


  Mycelial growth of colony, Produce fluffy, cottony, wooly, or powdery colonies on culture media, Microscopic appearance: Long tubular branching filamentous structure (Hyphae), Mycelium - mass of hyphae
• Different types of hyphae based on location in culture media

  • Aerial Hyphae: Extend above the surface of the colony, responsible for the fuzzy appearance, support reproductive structures (spores)
  • Vegetative Hyphae: Extend downwards into the medium, responsible for absorbing nutrients, anchor entire colony
• Candida albicans is a normal flora found in the oral cavity, skin, or genitalia but is opportunistic. It causes candidiasis (thrush) in immunocompromised individuals, cancer patients, pregnant women, babies, and neonates, diabetic individuals
• Different types of hyphae based on septation


  • Septate: With cross wall
  • Aseptate: Absence of cross wall
• Asexual reproduction of fungi, aka Imperfect reproduction, follows the process of mitosis
• Stains used for pigmented hyphae

  • Gomori methenamine silver nitrate stain
  • Fontana masson
• Sporangiospores formation


  1. Formed within a sac, called sporangium, at the end of an aerial hyphae (called sporangiosphore)

  2. As time progresses, the sac will burst out to release the single spores (sporangiospores) as single entity
• Arthrospores/Arthroconidia formation

  1. Formed by fragmentation of septated hyphae into single rectangular barrel-shaped thick-walled spores

  2. Cross wall thickens until it fragments out of the hyphae, becoming one single spore into one hyphal segment
• Blastospores/Blastoconidia formation


  Formed by budding from a mother cell pinching off its two daughter cells
• Developmental forms of conidia

  • Macroconidia
  • Microconidia
• Asexual Reproductive Structures

  • Arthrospores/Arthroconidia
  • Chlamydospore/Chlamydoconidia
  • Conidiospores
  • Sporangiospores
  • Blastospores/Blastoconidia
• Types of Pseudohyphae

  • Favic/antler hyphae
  • Nodular hyphae
  • Racquet hyphae
  • Spiral hyphae
  • Rhizoids
• Chlamydospore/Chlamydoconidia formation

  1. Formed by rounding up and thickening of septated hyphae within a single hyphal segment (circular)

  2. Three types: Terminal, Intercalary, Sessile
• Conidiospores production

  1. Produced in a chain at the end of conidiophore and not enclosed within a sac

  2. May be Aseptate or Septated hyphae
• Sexual Reproductive Structures

  • Ascopores
  • Basidiospores
  • Zygospores
• Sexual Phases of sexual reproduction

  1. Plasmogamy - fusion of two cells into their cytoplasm

  2. Karyogamy - fusion of nuclei after plasmogamy forming a zygote
• Basidiospores are formed at the surface of a specialized cell called basidium and are how the majority of mushrooms reproduce
• Division Basidiomycota undergoes both sexual and asexual reproduction, with Basidiospores being the sexual form
• Division Zygomycota undergoes both sexual and asexual reproduction, with Zygospores being the sexual form and Sporangiospores being the asexual form
• Candida albicans belongs to the Kingdom Fungi, Division Ascomycota, Class Saccharomycetes, Order Sccharomycetales, Family Sccharomycetaceae, Genus Candida, and Species albicans
• Sexual Reproductive Structures

  • Ascopores
  • Basidiospores
  • Zygospores
• Zygospores result when two nuclei that are morphologically similar to each other fuse, for example, Rhizopus stolonifer
• Fungi are classified based on their morphology, physiology, and genetic traits then placed in one group following established guidelines in taxonomy: Kingdom (Fungi) → Division/Phylum → Class → Order → Family → Genus → Species
• Ascospores result from the fusion of the nuclei of cells that can be morphologically similar/dissimilar inside a sac (ascus)
• Sexual reproduction

  1. Requires two cells

  2. Follows the process of meiosis, the union of two cells together to form a zygote
• Zygospores are produced when the two nuclei of two cells meet to form a zygote
• Divisions of Fungi


  • Zygomycota
  • Ascomycota
  • Basidiomycota
  • Chytridiomycota
  • Deuteromycota
• Division Ascomycota undergoes sexual reproduction with Ascospores and asexual reproduction with Conidiospores, Blastospores, and Arthrospores. It is considered the largest group of fungi with around 50,000 species classified
• Division Deuteromycota


  • Has the largest division of clinically significant members
  • Referred to as Fungi Imperfecti because they only reproduce asexually
• Specimen collection

  1. Collect from area most likely infected

  2. Use sterile technique

  3. Keep specimen moist

  4. Label container properly

  5. Transport right away

  6. Process right away
• Division Basidiomycota members

  • Cryptococcus neoformans – true yeast that causes systemic infection and meningitis
• Nail clippings

  1. Use sterile nail clippers by autoclaving

  2. Same procedures as skin scrapings
• Tissue mince/grinding

  1. Take by doctors

  2. Mince/grind tissue to force fungi from mass of tissue

  3. Process after