Mycology and Virology PDF

MICRO2 | Mycology and Virology BACHELOR OF SCIENCE IN MEDICAL LABORATORY SCIENCE 3 - 2 INTRODUCTION LESSON 1  Candida albicans; common colonization in the human...

MICRO2 | Mycology and Virology BACHELOR OF SCIENCE IN MEDICAL LABORATORY SCIENCE 3 - 2 INTRODUCTION LESSON 1  Candida albicans; common colonization in the human vagina causing candidiasis or moniliasis  Mycology  Requires a human body temperature  Medical Mycology o Filamentous molds  Fungi  Thrive in room temp; 25- 32  Tube-like filamentous organism o General Characteristics  Agents of diseases: cutaneous mycosis (superficial skin o Epidemiology infection, groin, scalp, fingernails), disseminated o Yeast deep-seated visceral disease (systemic mycosis)  Molds o True pathogens – historically pathogenic fungi; o Morphology pathogenic ever since o Hyaline vs pheoid o Opportunistic pathogens – saprophytic fungi. Main  Reproduction concerns of medical mycology. At risk:  Immunocompromised host  Taxonomy  Immunosuppressive infection: patient with HIV/AIDS or autoimmune diseases MYCOLOGY  High-dose cancer chemotherapy  Mycology is the study of fungi  Solid organ transplantation o Includes yeast, mold, and mushrooms FUNGI  Fungi are one of the largest microorganisms  Diverse group of organisms  Sabarose dextrose agar – fungi culture media  Classified as molds (filamentous) and yeasts (moist)  Fungi can be indentified based on their taxonomy,  Categories environmental impact, and genetic and biochemical o True pathogenic fungi properties o Opportunistic fungi TAXONOMY  Living on nonliving material  Determined by their unique reproductive structures  May cause a range of signs and symptoms and spore formation, hyphae, micellea, and o Mild to life-threatening conidium.  Ring worm, tenia pedis or athlete’s foot, especially  Spores and conidium are structures that fungi use for during rainy seasons or farmers reproduction, either asexually or sexually. UNIQUE o Significant in the immunocompromised patient with fungi, able to reproduce asexually and sexually GENERAL CHARACTERISTICS ENVIRONMENTAL IMPACT  Eukaryotic, they have true nuclei  Fungi play a crucial role in the environment as  Most fungi are saprophytic; they can decompose decomposers, they can break down complex organic organic matter like dead animals and recycle nutrients back into the ecosystem. It is  Fungi are important in life cycle processes vital for maintaining ecosystems  Fungi when they are exposed to moist environments  Some fungi can form symbiotic relationship with or in the body’s temperature, they exist as yeasts plants which enhance plant growth by improving absorption of nutrients  Fungi when in dry environment at room temperature, they can be molds GENETIC AND BIOCHEMICAL PROPERTIES o Bread molds  Fungi possess a remarkable array of enzymes that  Dimorphic – display both the characteristics of yeast allow them to break down tough substances like and mold forms lignin and cellulose o Thermally dimorphic fungi, require high temperature  The genetic diversity and the biochemical properties are subjects of intense researches  Polymorphic, it can assume one or more stage  Products of research based on the genetics and  Thick cell walls biochemical of fungi o Made of chitin o Antibiotics from penicillin notatum  Essential for the identification of fungi  Mostly obligate aerobes, they require oxygen for MEDICAL MYCOLOGY growth and for respiration  Study of fungi and their relationship to human  Prefer neutral pH disease SHARED CHARACTERISTICS  encompasses o Single-celled yeasts  Chitin in the cell wall  Ergosterol in the cell membrane  Reproduction by means of spores sexually or YEAST PSEUDOHYPHAE OF YEAST asexually o Asexual production  Blastoconidia  Arthroconidia o Sexual reproduction  Zygospores  Lack of chlorophyll, this distinguishes fungi from plants  Lack of susceptibility to antibacterial agent, difficult to treat o DO NOT USE ANTIBIOTICS o Antifungal drugs should be used EPIDEMIOLOGY  increased fungal infections worldwide. Escalated by: o Immunocompromised patients o Use of antifungal medications  Misuse of medications  More than 135,000 valid species of fungi CANDIDA ALBICANS o 1000-1500 newly identified annually  Implementation of molecular technology will continue PSEUDOHYPHAE to impact the evolution of the field of mycology  Chains of elongated yeasts of Candida albicans producing pseudohyphae observed in sputum YEAST  Single vegetative cells o Form a smooth, creamy, bacterial-like colony without aerial hyphae (protruding on the base of the agar plate)  ID is primarily based on biochemical testing and molecular diagnostic methods  Reproduction via budding or fission FORMATION OF BLASTOCONIDIA YEAST  The budding will start until a septum is developed into one blastoconidum MOLDS  Group of hyphae are called mycelium  Filamentous mycelium o long strands of tubelike structures called hyphae BUDDING AND NONBUDDING YEAST CELLS  Reproduction by spores asexually or sexually  The septum is the partial wall between the mother o Vegetative mycelium(sexual) cell and the daughter cell  Obtain nutrients from the source  Arthrospores, chlamydospores, blastospores  Rhizoids o Aerial mycelium(asexual)  Conidia, sporangia  An aerial mycelia can be seen by the naked eye and give a wooly appearance  A vegetative mycelia can be used for absorption of -BUDDING nutrients in the agar plate -NON BUDDING  MOLD MORPHOLOGY  Hyphae SEPTATE o Shape  Antler, antler of elks  Racquet, just like tennis rackets  Spiral  Rhizoids o Septate  Frequent perpendicular cross-walls  Partition within the hyphae  Feoacremonium species with septation NONSEPTATE HYPHAE  The branching is not distinct compared to the septate hyphae o Sparesely septate  Frequent perpendicular cross-walls  Representative of mucorails from a tissue sample HYALINE VS PHAEOID  Hyaline (transparent) o Nonpigmented o Lightly pigmented  Phaeoid (Dematiaceous) o Darkly pigmented  Melanin production in cell wall  E.g Bipolaris spp. FILAMENTOUS NATURE OF MOLD  From Aspergilus fumigatus, gives colonies a wooly,  The conidiophore will hold the vase like structure, fluffy, velvety, and sometimes punctuatued with a phialide, and producing phialoconidia granular or powedery aspect that is due to the FORMATION OF ARTHROCONIDIA formation of asexual reproductive structures  Arthocronidia are formed or developed following the fragmentation of fertile hyphae DIMORPHISM  Can be a mold or a yeast given in the place of temperature o Mold phase  22 to 25° C (room temperature) o Yeast phase  37° C with increased carbon dioxide (CO2)  Candida albicans POLYMORPHISM  The ability to form yeast and mold in same culture o Generally yeast first moving to mold as culture ages  Ex. Exophiala spp.  Aspergilus spp  The foot cell which serves as the base of the REPRODUCTION conidiphore.  Asexual reproduction  The coniophore has a swollen vesicel and optuet of o Conidia (conidium) following mitosis steregnatea that oroduces chains of conidia  Fruiting structures  Phialoconidia  Highly fata systemic fungal infection or the San  Annellide ring structures Joaquin Valley fever and are barrle shaped. Has a o Phialides thin walled juncture cell *bottom left image*  Vase-like structures that produce phialoconidia  Conidogenous cell SEXUAL REPRODUCTION o Annellide o Teleomorph  Ringed structures that produce annelloconidia  Anamorph ASEXUAL REPRODUCTION PRODUCING o Occasionally reproduce asexually PHIALOCONIDIA  Synanamorphs o Name for amorphic strains when more than one anamorph is present for the same teleomorph o Different asexual forms in the same fungus ZYGOSPORE FORMATION ASEXUAL REPRODUCTION BY MUCORALES SPORANGIOPHORES TAXONOMY NOMENCLATURE  Historically, fungi have carried multiple names (genera and species) associated with reproductive forms o Obsolete: The International Botanical Congress (July 2011) adopted a one fungus, one name policy published in the International Code of Nomenclature, Article 59. o International Code of Nomenclature for Algae, Fungi, and Plants (January 1, 2013)  Previously called International Code of Botanical Nomenclature ASCOMYCOTA TAXONOMY OF CLINICALLY SIGNIFICANT FUNGI  Sexual spores  The causative agents of clinical infections are found in four o Ascospores groups of fungi  Contained in a saclike structure o Phylum Ascomycota  Ascus  Asexual reproduction by conidia  Sexual reproduction by ascospores o Species o Phylum Basidiomycota  Microsporum spp.  Trichophyton spp.  Sexual reproduction via basidiospores (on basidia)  Scedosporium boydii o Subphylum Mucoromycotina & Entomophythoromycontina  replaced Phyla Zygomycota ASCOSPORES  Asexual reproduction by sporangiospores  Sexual reproduction by zygospores o Form division fungi Imperfecti (Deuteromycota) o No sexual phase MUCORALES  The most significant order o Rapid growers o Produce gray to white aerial mycelium with hyaline, sparsely septate hyphae o Opportunistic pathogen in the immunocompromised MACROCONIDIA o Asexual reproduction  Sporangiophores and sporangiospores  Results in zygospores (not seen in clinical laboratories) o Example members—Mucor, Rhizopus, Lichtheimia (Absidia), Cunninghamella  Formerly under the class of zygomycetes  Mucormicoses, highly vulnerable to diabetic patients and immunocompromised BASIDIOMYCOTA MALASSEZIA SKIN DISEASE  Only pathogen o Filobasidiella neoformans  Sexual form of Cryptococcus neoformans var. neoformans o Other genera associated with human infections  Malassezia, Trichosporon o ID  Clamp connections at septations CRYPTOCOCCUS NEOFORMANS 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 PARAFUNGAL ORGANISMS  Organisms that resemble yeast and Protozoans  Remain unculturable  Atypical agents of human infection *additional since kulang sa Henrys Zygospore- a thick-walled sexual spore formed by the fusion of two similar gametangia; characteristic of the Zygomycetes