Introduction to Mycology

Ergosterol

cell membrane bilayer component found in fungi, similar to cholesterol in animal cells. It plays a crucial role in maintaining membrane structure and function.

India ink

stain used for fungi

Hypha

Basic structural unit

Mycelium

Aggregates of hypha

Septate hypha

with crosswalk/partitions

Aseptate hypha

continuous, non-segmented strands of hyphae (Zygomycetes, Rizous, Mucor)

Mold phase

• cottony mycelial mass

• room temp

• occurs in filaments, hyphae

Yeast phase

• Creamy colonies resembling bacteria

• Grows at 37

• Solitary cells produce by budding

Monomorphic

Mold or yeast

Dimorphic

Capable of 2 growths (mold or yeast)

Mycelium, fruitbody

Parts of fungi

Fungi imperfecti

Asexual reproduction

Perfect fungi

Asexual and sexual reproduction modes, known for producing specialized reproductive structures.

Asexual reproduction

Budding, fragmentation, fission

Mitosis

cell division for asexual reproduction

Sporangiospores

enclosed in sporangium (rhisopus, mucor)

Conidiospores

end of hyphae (aspergillus, penicillium) that are asexually produced.

Chlamydospores

In between hyphae (candida)

Arthrospores

fragmentation of hyphae (trichosporon)

Blastospores

budding (Candida albicans)

Sexual reproduction

Fusion of 2 hyphae with their nuclei

Heterothallic

requires another individual thallus

Homothallic

ability to self-fertile

Ascospores

enclosed in ASCUS/ASCI

Zygospores

fusion of 2 gametes/haploid nuclei (zygomycetes)

Oospore

forms when an oogonium (female gamete) fuses with an antheridial (male gamete), producing a thick-walled spore (Oomycota)

Basidiospore

Enclosed in a club-shaped basidium (Basidiomycetes)

Ascospores

Sporotrichosis

rose gardener disease

Inhalation/direct contact

mode of transmission

KOH mount 10%

dissolves keratin

Staining

India ink, methenamine silver, calcofluor white

Periodic acid schiff

in fungi, magenta color

Lactophenol cotton blue

blue discoloration of CW

Saboraud dextrose agar

general isolation (nocardia bac)

Mycosel/Mycobiotic

SDA + Cycloheximide, inhibits fast-growing fungi, chloramphenicol

Cornmeal agar

studying mycelium or pseudomycelium

Birdseed agar

used for the cultivation of Cryptococcus species, contains nutrients for yeast growth.

Cottonseed agar

use to convert Blastomyces mold to yeast phase

Germ tube test

• out grow produced by spores

• releasing fungi during germination

Urease test

Cryptococcus neoformans, Coccidioides immitis, Histoplasma capsulatum, Sporothrix schenckii, Trichosporon. Aspergillus.

Hair Perforation Test

use to differentiates Dermatophytes

Polyenes

binds to Ergosterol; Amphotericin B

Azoles

inhibits conversion of lanosterol to ergosterol; Miconazole

Allylamines

inhibits epoxidase; Terbinafine

Echinocandins

inhibits glucan formation; Caspofungin

Exogeneous Route

Airborne, Cutaneous (Trauma/Direct Inoculation)

Endogenous Route

Colonization By Normal Flora

Primary Infection

Direct Infection/Establishment Of Pathogen

Opportunistic

Causes Diseases In Immunocompromised/ Weakened Immune System

Superficial mycoses

• Affects the superficial layer of the skin

• Confined to the Striatum corneum

• Does not illicit inflammation

Tinea versicolor

Malassezia furfur

Cutaneous mycoses

• involve the integument and its appendages

• Can illicit inflammation

• DERMATOPHYTOSIS

• Dermatophytes: Trichophyton, Microsporum, Epidermophyton

• Stratum corneum

Tinea corporis

Trichophyton

Subcutaneous mycoses

• infects the subcutaneous tissues usually at the point of traumatic inoculation

• inflammatory response develops in the subcutaneous tissue frequently with extension into the epidermis

Sporotrichosi

Sporothrix

Deep/system mycoses

• Involves organ systems

• Route: Respiratory, digestive, circulatory

Histoplasma capsulatum

is a dimorphic fungus that causes histoplasmosis, primarily affecting the lungs and can disseminate to other organs, particularly in immunocompromised individuals.