Fungi Microbiology Lecture - UAG School of Medicine PDF

WE MAKE DOCTORS FUNGI Arturo Ochoa, M.D.  Identify the main Define the different characteristics of the types of fungal infection fungal structure as...

WE MAKE DOCTORS FUNGI Arturo Ochoa, M.D.  Identify the main Define the different characteristics of the types of fungal infection fungal structure as as superficial, mucosal, eukaryotes in the subcutaneous, deep- classification for yeast or systemic, opportunistic mold mycoses Recognize and associate Recognize the the main virulence reproduction differences factors involved in the and the stimuli pathogenesis process necessary to enter and outcome in fungi different stages in their disease life cycle Definition Fungi are eukaryotes and occupy their own kingdom. They have a thick carbohydrate cell wall containing chitin, glucans, mannans and glycoproteins. Mycoses are infections caused by fungi such as dermatophytes, yeasts, or molds. Fungi Terminology Hyphae: Tubular, branching filaments of fungal cells, with or without septae Image: AMBOSS. (2024) General Micology of the AMBOSS article. Retrieved from https://next.amboss.com/us/article/KM0Upg?q=fungi Septa: Hyphal cell wall divisions, typically porous Pseudohyphae: A hyphae-like filament formed by a chain of budding yeast cells that have not become detached from each other. Fungi Terminology Mycelium: A haploid and multicellular network of hyphae forming a thread-like structure Pseudomycelium: Mycelium-like mass of pseudohyphae Thallus: The vegetative body of a fungus Sporangia: A spore-forming structure Fungi Terminology Spores: Haploid reproductive particles that can be formed on reproductive hyphae or mycelium May result from asexual or sexual production Sporangiophore: Modified hyphae bearing sporangia Conidia: Asexual spore of a fungus May bud in clusters of chains Produced by most pathogenic fungi Image: AMBOSS. (2024) General Micology of the AMBOSS article. Retrieved from https://next.amboss.com/us/article/KM0Upg?q=fungi Fungi Terminology Conidiophore: Simple or branched hyphae on which conidia are produced Germ tube: An outgrowth produced by spores during germination No constrictions at the site of origin Anamorph: Asexual reproductive state of a fungus Fungi Terminology Teleomorph: Sexual reproductive state of a fungus Conidium: An asexual fungus spore formed from a vegetative yeast, hyphal cell, or a specialized conidiogenous cell Microconidium: a small asexual fungal spore Macroconidium: a large asexual fungal spore Fungi Structure Fungi vary widely in size and shape, microscopically are either yeasts or molds, or both. Eukaryotes Most are obligate or facultative aerobes Asexually, sexually, or both Chemotropic organisms Fungi Structure Fungal cell wall: chitin, glucans, and mannans Fungal cell membrane: contains ergosterol Cell membrane component unique to fungal species Important enzymes squalene epoxidase and 14-a- demethylase Julie M. Wolf and Arturo Casadevall. (2014) Challenges posed by extracellular vesicles from eukaryotic microbes. Current opinion in biology. 22, 73-78. Retrieved from ClinicalKey. Fungi Structure Monomorphic fungi: Yeasts: unicellular fungi, occasionally organize into hyphae and pseudohyphae Molds: multicellular fungi, organized into hyphae Dimorphic fungi: Molds typically grow at approximately 20°C and yeast at 37°C Histoplasma capsulatum, Blastomyces dermatitidis, Coccidioides immitis, Paracoccidioides brasiliensis, and Sporothrix schenckii Yeast Morphology: Unicellular fungi that typically reproduce by budding or fission. They are generally round or oval in shape. Growth: Yeasts grow as single cells and form smooth, creamy colonies on solid media. They do not form the filamentous structures seen in molds. Examples: Saccharomyces cerevisiae, Candida Albicans Image: AMBOSS. (2024) General Micology of the AMBOSS article. Retrieved from https://next.amboss.com/us/article/KM0Upg?q=fungi Mold Morphology: Molds are multicellular fungi that grow in the form of hyphae, which are long, thread-like structure. These hyphae form a network called mycelium. Growth: Molds grow as multicellular filaments and form fuzzy or woolly colonies on solid media. They produce spores that can be airborne and contribute to their spread. Examples: Aspergillus, and Penicillium Image: AMBOSS. (2024) General Micology of the AMBOSS article. Retrieved from https://next.amboss.com/us/article/KM0Upg?q=fungi Fungi Replication Fungi reproduce through sexually and/or asexually produced spores Asexual reproduction of fungi Asexual spore production, a haploid cell is produced via mitosis and released from parent body “Fungal fragmentation”: A portion of the mycelium splits from the body of the fungus “Binary fission”: A cell undergoes nuclear division and splits into two daughter cells Fungi Replication Budding An outgrowth, bud, or appendage develops on the surface of the cell or the hypha, with its cytoplasm being continuous with that of parent cell Asexual spores Conidiospore: a single-cell that arises on the tip of a hyphal structure called conidiophore Sporangiospore: Produces in a sac-like structure called sporangia Arthrospere: Formed by the fragmentation of a disjunctor cell Chlamydospore: A single-cell spore in or on hyphae Blastospore: A budding spore usually formed at the terminal end of a hypha Fungi Replication Sexual reproduction of fungi: Plasmogamy, Karyogamy, and Meiosis Union of two haploid cells, follows plasmogamy and karyogamy, producing a diploid zygote Main methods of plasmogamy Gametangium: Organ or cell in which gametes are produced Somatogamy: Somatic hyphae take over the sexual function Spermatization: Fungi male fungal spermatia attaches to female hyphae or gametangia Fungi Replication Sexual spores Ascospores: Produced in a sac-like structure called “ascus” Basidiospores: Produced in a club-shaped structure called a “basidium” Zygospore: Formed when two sexually compatible hyphae or gametangia fuse Oospores: A thick-wall spore, formed when a female gamete is fertilized by a male gamete nucleus Fungal Metabolism Fungi have a variety of metabolic pathways, deriving their energy from the breakdown of organic compounds, where enzymes are needed. Substances synthetized by fungi: Primary metabolites Secondary metabolites Fungal Metabolism Primary Metabolites Compounds responsible growth and energy storage Act as intermediates in the biosynthesis of secondary metabolites Secondary Metabolites Antibiotics Toxins: Aflatoxins by molds “poisonous carcinogen” Amanitins Ergot alkaloids: ergotamine by ergot fungus Fungi Dermatophytes: filamentous fungi Trichophyton Microsporum Epidermophyton Yeasts: budding fungi Candida Cryptococcus neoformans Malassezia furfur Molds: Aspergillus fumigatus Dimorphic fungi: Blastomyces dermatitidis Coccidioidomycosis Histoplasma capsulatum Sporothrix schenckii Dermatophytes Tricophyton species Worldwide Yellow-green fluorescence on Wood lamp Epidermophyton species Worldwide No typical fluorescence Microsporum species Worlwide Partial Blue-Green fluorescence Dermatophytes Tinea Corporis (ring worm) Tricophyton rubrum Tinea Capitis Tricophyton tonsurans, Microsporum canis, Microsporum audouinii Tinea unguium (onychomycosis) Tricophyton rubrum Tinea cruris (Jock Itch) Tricophyton rubrum Tinea pedis (athlete’s foot) Tricophyton rubrum, Tricophyton interdigitale Image: AMBOSS. (2024) General Micology of the AMBOSS article. Retrieved from https://next.amboss.com/us/article/KM0Upg?q=fungi Yeasts Candida species Candida albicans is the most common, worldwide, and almost exclusively found in humans Malassezia furfur Humans are infected via contaminated dust particles Possesses a capsule visualized with India ink Cryptococcus neoformans Yellow-orange fluorescence Particularly present in the infundibulum of hair follicle Yeasts Candida species Vaginal yeast infection/balanitis, Candida albicans Erosiointerdigitalis blastomycetica Oral thrush Candida esophagitis Candida intertrigo Invasive candidiasis Image: AMBOSS. (2024) General Micology of the AMBOSS article. Retrieved from https://next.amboss.com/us/article/KM0Upg?q=fungi Image: AMBOSS. (2024) General Micology of the AMBOSS article. Retrieved from https://next.amboss.com/us/article/KM0Upg?q=fungi Yeasts Cryptococcus neoformans Cryptococcal meningitis Cryptococcocis Malassezia furfur Tinea versicolor Involved in seborrheic eczema Image: AMBOSS. (2024) General Micology of the AMBOSS article. Retrieved from https://next.amboss.com/us/article/KM0Upg?q=fungi Molds Aspergillus fumigatum Usually opportunistic agent Formation of monomorphic septate hyphae that branch at 45° and mycelium Some species (Aspergillus flavus) can produce aflatoxins which are carcinogenic, induces TP53 mutation Image: AMBOSS. (2024) General Micology of the AMBOSS article. Retrieved from https://next.amboss.com/us/article/KM0Upg?q=fungi Molds Apergillosis Aspergilloma Endocarditis Image: AMBOSS. (2024) General Micology of the AMBOSS article. Retrieved from https://next.amboss.com/us/article/KM0Upg?q=fungi Important fungal diseases Type Anatomic Representative Causative Growth form in location(s) disease organisms human body Superficial Hair shaft, skin White piedra Trichosporon Y/F Black piedra Piedraia hortae Pityriasis Malassezia versicolorSebor Hortaea rheic dermatitis werneckii Tinea nigra Cutaneous Epidermis, hair, Tinea Microsporum , F nails (ringworm) Trichophyton , Epidermophyton, Nannizzia a Subcutaneous Dermis, Sporotrichosis Sporothrix Y subcutis Eumycetoma Several genera F Chromoblasto Several genera Y/F mycosis Lacazia loboi Yeast-like Lobomycosis Important fungal diseases Type Anatomic Representative Causative Growth form in location(s) disease organisms human body Systemic Internal organs Coccidioidomyc Coccidioides Form b osis spherules Histoplasmosis Histoplasma Y Blastomycosis Blastomyces Y Paracoccioidom Paracoccidioides Y ycosis Opportunistic Internal organs Cryptococcosis Cryptococcus Y c Candidiasis Candida Y a Aspergillosis Aspergillus F Mucormycosis Mucorales N/A Pneumocystis Pneumocystis N/A c pneumonia Emergomyces Y Emergomycosis References Amboss. (2024). General Micology. Retrieved November 4, 2024, from https://next.amboss.com/us/article/KM0Upg?q=fungi Richard, Goering., Dockrell, Hazel., Zuckerman, Mark., Chiodini, Peter.(2024) Mims' Medical Microbiology and Immunology, Elsevier. 7th Ed. Chapter 4, pages 35-39. Patrick R. Murray, Ken S. Rosenthal (2020). Medical Microbiology (9th edition). Elsevier. Chapter 57, pages 572-577.