MICROPARA - MODULE 4

Mycology

Study of fungi

Fungi

Eukaryotic, non-photosynthetic organisms; may be unicellular (yeasts) or multicellular (molds)

Saprophytes

Fungi that live on dead organic matter

Parasites

Fungi that live on or within a host, deriving nutrients at host’s expense

Yeast

Unicellular fungi that reproduce by budding or fission

Mold

Multicellular fungi with filamentous structures (hyphae) that form mycelium

Dimorphic Fungi

Fungi capable of growing as mold or yeast depending on environmental conditions

Hyphae

Threadlike filaments that make up the body (mycelium) of a fungus

Septate Hyphae

Hyphae divided by cross-walls (septa)

Coenocytic Hyphae

Hyphae without septa; multinucleated

Vegetative Hyphae

Hyphae that grow along surface or into medium; absorb nutrients

Reproductive Hyphae

Hyphae that produce spores for reproduction

Mycelium

Mass of hyphae; visible fungal colony

Asexual Spores

Reproductive spores formed by mitosis; include conidia and sporangiospores

Conidia

Asexual fungal spores not enclosed in sac; borne on specialized hyphae (conidiophores)

Sporangiospores

Asexual spores formed within a sac (sporangium) at the end of hypha

Sexual Spores

Reproductive spores formed by fusion of nuclei from two opposite mating strains

Zygospore

Sexual spore formed by fusion of similar gametangia in Zygomycota

Ascospore

Sexual spore formed within a saclike structure (ascus) in Ascomycota

Basidiospore

Sexual spore formed externally on club-shaped structure (basidium) in Basidiomycota

Chlamydospore

Thick-walled asexual spore formed for survival in harsh conditions

Blastospore

Budding asexual spore typical of yeasts

Zygomycota

Phylum of fungi with coenocytic hyphae; reproduce sexually via zygospores and asexually by sporangiospores

Ascomycota

Sac fungi; produce sexual ascospores in asci and asexual conidia

Basidiomycota

Club fungi; produce sexual basidiospores on basidia (e.g., mushrooms)

Deuteromycota

Fungi with no known sexual stage; classified by asexual reproduction

Mycosis

Fungal infection in animals or humans

Superficial Mycoses

Fungal infections limited to outermost skin and hair (e.g., tinea versicolor)

Cutaneous Mycoses

Fungal infections of skin, hair, and nails caused by dermatophytes (e.g., ringworm)

Subcutaneous Mycoses

Fungal infections beneath the skin from traumatic implantation

Systemic Mycoses

Deep fungal infections affecting internal organs; often inhaled spores

Opportunistic Mycoses

Infections by normally harmless fungi in immunocompromised hosts (e.g., Candida, Aspergillus)

Dermatophytes

Fungi that infect keratinized tissues (skin, nails, hair)

Candida albicans

Opportunistic yeast that can cause oral thrush and vaginal candidiasis

Aspergillus

Fungus causing aspergillosis; opportunistic pathogen in lungs

Cryptococcus neoformans

Encapsulated yeast causing meningitis in immunocompromised patients

Histoplasma capsulatum

Dimorphic fungus causing histoplasmosis; transmitted by inhaling spores from soil with bird/bat droppings

Blastomyces dermatitidis

Dimorphic fungus causing blastomycosis; inhaled spores affect lungs

Coccidioides immitis

Dimorphic fungus causing coccidioidomycosis (Valley fever)

Pneumocystis jirovecii

Opportunistic fungus causing pneumonia in immunocompromised patients

Sporothrix schenckii

Dimorphic fungus causing sporotrichosis; acquired via skin puncture (rose gardener’s disease)

Aflatoxin

Toxin produced by Aspergillus species; potent hepatotoxin and carcinogen

Ergot

Claviceps purpurea fungus infecting grains; produces alkaloids that cause ergotism

Mycotoxin

Toxic secondary metabolite produced by fungi

Sabouraud Agar

Culture medium commonly used for growing fungi

Lactophenol Cotton Blue Stain

Stain used for microscopic observation of fungal morphology

KOH Preparation

Method for direct microscopic examination of clinical specimens for fungi

Fungal Dimorphism

Ability of some fungi to exist in yeast form in body and mold form in environment