Introduction To Mycology PDF

Introduction to Mycology Charlie P. Cruz, SM (ASCP), RMT Course Instructor/Facilitator 1 Introduction College of Medical Laboratory Science, Lorma Colleges 2  Mycology  Mycology is the stud...

Introduction to Mycology Charlie P. Cruz, SM (ASCP), RMT Course Instructor/Facilitator 1 Introduction College of Medical Laboratory Science, Lorma Colleges 2  Mycology  Mycology is the study of fungi  Taxonomy  Environmental impact  Genetic and biochemical properties 3  Medical Mycology  study of fungi and their relationship to human disease  encompasses  Single-celled yeasts  Filamentous molds agents of diseases: superficial skin infection (cutaneous mycosis), disseminated deep-seated visceral disease (systemic mycosis)  true pathogens – historically pathogenic fungi  opportunistic pathogens – saprophytic fungi  Immunocompromised host  Immunosuppressive infection: HIV/AIDS  High-dose cancer chemotherapy  Solid organ transplantation College of Medical Laboratory Science, Lorma Colleges 4 Common Terms in Medical Mycology College of Medical Laboratory Science, Lorma Colleges 5  Overview of Fungi  Diverse group of organisms  Classified as molds (filamentous) and yeasts (moist)  Categories  Classic pathogens  Environmental saprobes Living on nonliving material  May cause a range of signs and symptoms  Mild to life-threatening  Significant in the immunocompromised patient College of Medical Laboratory Science, Lorma Colleges 6 General Characteristics College of Medical Laboratory Science, Lorma Colleges 7  General Characteristics  Eukaryotic  Most fungi are saprophytic (they live on dead organic matter)  Fungi are yeasts (moist) and/or molds (filamentous)  Organisms that display both yeast and mold forms are dimorphic  They are thermally dimorphic when dependent on temperature 8  General Characteristics (cont.)  Fungi that have more than one form or stage are polymorphic  Thick cell walls  Made of chitin  These properties allow the absorbing of specialized dyes used in identification (ID).  Mostly obligate aerobes  Prefer neutral pH 9  Shared Characteristics  Chitin in the cell wall  Ergosterol in the cell membrane  Reproduction by means of spores sexually or asexually  Lack of chlorophyll  Lack of susceptibility to antibacterial agents 10  Epidemiology  Increased fungal infections worldwide  Immunocompromised patients  Use of antifungal medications  More than 135,000 valid species of fungi  1000-1500 newly identified annually  Implementation of molecular technology will continue to impact the evolution of the field of mycology College of Medical Laboratory Science, Lorma Colleges 11  Yeasts  Single vegetative cells  Form a smooth, creamy, bacterial-like colony without aerial hyphae  ID is primarily based on biochemical testing and molecular diagnostic methods.  Reproduction via budding or fission College of Medical Laboratory Science, Lorma Colleges 12 Formation of Blastoconidia in Yeast 13 Budding and Nonbudding Yeast Cells 14 Yeast Pseudohyphae of Yeast College of Medical Laboratory Science, Lorma Colleges 15  Pseudohyphae College of Medical Laboratory Science, Lorma Colleges 16  Molds  Filamentous mycelium  Long strands of tubelike structures called hyphae  Reproduction by spores asexually or sexually  Vegetative mycelium Arthrospores, chlamydospores, blastospores Rhizoids  Aerial mycelium Conidia, sporangia College of Medical Laboratory Science, Lorma Colleges 17 Visual Representation of Aerial and Vegetative Mycelia College of Medical Laboratory Science, Lorma Colleges 18  Mold Morphology  Hyphae  Shape Antler Racquet Spiral Rhizoids  Septate Frequent perpendicular cross-walls  Sparsely septate Frequent perpendicular cross-walls College of Medical Laboratory Science, Lorma Colleges 19 Septate Versus Sparsely Septate College of Medical Laboratory Science, Lorma Colleges 20 Septate Hyphae 21 Nonseptate Hypha 22  Hyaline Versus Phaeoid  Hyaline  Nonpigmented  Lightly pigmented  Phaeoid (Dematiaceous)  Darkly pigmented Melanin production in cell wall College of Medical Laboratory Science, Lorma Colleges 23 Filamentous Nature of Mold College of Medical Laboratory Science, Lorma Colleges 24  Dimorphism and Polymorphism  Dimorphism  Ability to exist in two forms based on growth conditions Mold phase  22 to 25° C (room temperature) Yeast phase  37° C with increased carbon dioxide (CO2)  Polymorphism  The ability to form yeast and mold in same culture Generally yeast first moving to mold as culture ages  Ex. Exophiala spp. College of Medical Laboratory Science, Lorma Colleges 25  Reproduction  Asexual reproduction  Conidia (conidium) following mitosis Fruiting structures  Phialoconidia  Annellide ring structures  Phialides Vase-like structures that produce phialoconidia  Annellides Ringed structures that produce annelloconidia College of Medical Laboratory Science, Lorma Colleges 26 Asexual Reproduction Producing Phialoconidia College of Medical Laboratory Science, Lorma Colleges 27 Formation of Arthroconidia College of Medical Laboratory Science, Lorma Colleges 28 Conidiophore and Arthroconidia College of Medical Laboratory Science, Lorma Colleges 29  Reproduction  Sexual reproduction  Teleomorph  Anamorph  Occasionally reproduce asexually  Synanamorphs  Name for amorphic strains when more than one anamorph is present for the same teleomorph  Different asexual forms in the same fungus College of Medical Laboratory Science, Lorma Colleges 30 Zygospore Formation College of Medical Laboratory Science, Lorma Colleges 31  Taxonomy College of Medical Laboratory Science, Lorma Colleges 32  Nomenclature  Historically, fungi have carried multiple names (genera and species) associated with reproductive forms  Obsolete: The International Botanical Congress (July 2011) adopted a “one fungus, one name policy” published in the International Code of Nomenclature, Article 59.  International Code of Nomenclature for Algae, Fungi, and Plants (January 1, 2013) Previously called the International Code of Botanical Nomenclature College of Medical Laboratory Science, Lorma Colleges 33 Taxonomy of Clinically Significant Fungi  The causative agents of clinical infections are found in four groups of fungi  Phylum Ascomycota Asexual reproduction by conidia Sexual reproduction by ascospores  Phylum Basidiomycota Sexual reproduction via basidiospores (on basidia) College of Medical Laboratory Science, Lorma Colleges 34 Taxonomy of Clinically Significant Fungi  The causative agents of clinical infections are found in four groups of fungi  Subphylum Mucoromycotina & Entomophythoromycotina replaced Phylum Zygomycota Asexual reproduction by sporangiospores Sexual reproduction by zygospores  Fungi Imperfecti formerly classified in the form phylum Deuteromycota no sexual phase 35  Mucorales  The most significant order  Rapid growers  Produce gray to white aerial mycelium with hyaline, sparsely septate hyphae  Opportunistic pathogen in the immunocompromised  Asexual reproduction Sporangiophores and sporangiospores Results in zygospores (not seen in clinical laboratories)  Example members—Mucor, Rhizopus, Lichtheimia (Absidia), Cunninghamella College of Medical Laboratory Science, Lorma Colleges 36 Asexual Reproduction by Mucorales College of Medical Laboratory Science, Lorma Colleges 37 Sporangiophores 38  Ascomycota  Sexual spores  Ascospores Contained in a saclike structure  Ascus  Species  Microsporum spp.  Trichophyton spp.  Scedosporium boydii College of Medical Laboratory Science, Lorma Colleges 39 Ascospores 40  Macroconidia College of Medical Laboratory Science, Lorma Colleges 41  Basidiomycota  Only pathogen  Filobasidiella neoformans Sexual form of Cryptococcus neoformans var. neoformans  Other genera associated with human infections  Malassezia, Trichosporon  ID  Clamp connections at septations College of Medical Laboratory Science, Lorma Colleges 42 Cryptococcus neoformans College of Medical Laboratory Science, Lorma Colleges 43 Malassezia Skin Disease College of Medical Laboratory Science, Lorma Colleges 44  Fungi Imperfecti  Contains the largest number of causative agents of mycoses  Organisms are placed in this group when no mode of sexual reproduction has been identified.  These organisms are identified on the basis of characteristic asexual reproductive structures.  Examples: Ulocladium, Alternaria tenuis College of Medical Laboratory Science, Lorma Colleges 45  Parafungal Organisms  Organisms that resemble yeast and Protozoans  Remain unculturable  Atypical agents of human infections College of Medical Laboratory Science, Lorma Colleges 46