OPT 416 Microbiology and Immunology Fungi PDF

OPT 416 MICROBIOLOGY AND IMMUNOLOGY FUNGI Dr. Nur Ayunie Zulkepli Center for Medical Laboratory Technology Studies [email protected]  LEARNING OBJECTIVES AT THE END OF THE LESSON, STUDENTS ARE ABLE T...

OPT 416 MICROBIOLOGY AND IMMUNOLOGY FUNGI Dr. Nur Ayunie Zulkepli Center for Medical Laboratory Technology Studies [email protected]  LEARNING OBJECTIVES AT THE END OF THE LESSON, STUDENTS ARE ABLE TO EXPLAIN OR IDENTIFY: Basic characteristic of the fungi Classification of fungi and fungal diseases  General Characteristics Of Fungi Myco = Fungus in Greek Mycology: Study of fungi, (Kingdom Myceteae = kingdom Fungi) Medical mycology: Study of medically important fungi and their diseases Mycoses: A disease caused by a fungus Saprobic: feed on dead All Eukaryotic tissues or organic (a true nucleus) waste (decomposers) Characteristics of fungi: Symbiotic: mutually beneficial relationship Heterotrophic: between a fungus and another organism Parasitic: feeding on Do not have chlorophyll living tissue of a host (Achlorophyllous) (disease) Extra: Unicellular & multicellular Mannan and Glucan Chitin are targets The cell is surrounded by a for the rigid cell wall made of: diagnosis Complex carbohydrates of fungal (Mannan, Glucan) infections.  Morphology Types of morphology: Yeasts: Filamentous "Mold" fungi: Dimorphic unicellular (Hyphae, organisms mycelium) Hyphae are multicellular Yeast: Parasitic filamentous Filamentous: form, Tissue structures, Saprophytic form, constituted by form, Cultured Cultured at 37° C tubular cells at 25 C with cell walls. Dimorphic: Have two forms depending on change in the environmental factors (Ex: Temperature) Mold form Yeast form  Yeasts Morphology: Reproduction: Examples: Clinical Examples: Candida Albicans (found as normal flora) Colony Budding Pseudohyphae Extra: Pseudo = not true (Asexually) Saccharomyces hyphae but it still a yeast cerevisiae (found in Baking Powder) Saccharomyces Candida Albicans Pseudohyphae Yeasts budding cerevisiae stained  Filamentous (Mold) fungi A hypha: Mycelium: Conidia/Spore: Examples: (plural hyphae) (colony) Aspergillus (Extra: very common A long, branching pathogenic filamentous fungi) filamentous cell. The intertwined Asexual spores born hyphae are the mass of hyphae externally on Penicillium main mode of that forms the hyphae or on a (Extra: synthesize penicillin) vegetative growth. fungal colony. conidiophore. Rhizopus (Extra: causes Black bread mold) Aspergillus species Penicillium Rhizopus  Selected Features of Fungi and bacteria compared Selected Features of Fungi and bacteria compared Fungi Bacteria Cell Type Eukaryotic Prokaryotic Sterols absent, except in Cell Membrane Sterols present Mycoplasma Glucans, mannans, chitin Cell Wall Peptidoglycan (no peptidoglycan) Sexual and asexual reproductive Endospores (not for reproduction), Spores spores some asexual reproductive spores Hetrotrophic, autotrophic, Limited to hetrotrophic, aerobic, Metabolism aerobic, facultatively anaerobic, facultatively anaerobic anaerobic  Filamentous fungi (mold) The threads (hyphae) are actually tubular cells that, in some fungi, are partitioned into segments (septate); whereas, in other fungi, the hyphae are uninterrupted by cross walls (nonseptate). Mycelium is the intertwined mass of hyphae that forms the fungal colony , and conidia is spore produced asexually by various fungi at the tip of a specialized hypha. Examples: penicillium, aspergillus and rhizopus  MORPHOLGY Moniliaceous Dematiaceous molds: Molds: Are pigmented. hyaline or lightly Because of the pigmented e.g. pigment, the conidia or Aspergillus, colonies appear hyphae, Penicillium dark, brown, or colorless black  Reproduction in Fungi Reproduction in Fungi Asexual (Only undergo Sexual mitotic cell division) Meiosis of this Fusion of two transient diploid Spores compatible Mitosis to form Somatic formation a transient become sexual strains of the spores (Asexual sporulation) same species diploid (ascospores) Yeasts by Molds by hyphal budding fragmentation  PATHOGENICITY OF FUNGI  Spores: These are the small airborne particles by which fungi reproduce, they are produced and disseminate in the air.  Fungi can cause diseases to humans Cause superficial infections some can cause allergic reactions Few cause invasive infections  Not all fungi are pathogenic, to cause the disease: Thermotolerance Ability to survive in tissue environment Ability to withstand host defenses Mycotic Infections Mycotic Infections ORGANISM: Genus/Species: There are a large number of different genera and species of fungi that cause human diseases. Only a few of these specific agents will be presented and discussed GENERAL CONCEPTS: The fungi represent a diverse, heterogeneous group of eukaryotes. Most of these organisms are plant pathogens and relatively few cause disease in humans. In nature, fungi generally grow by secreting enzymes that digest tissues but some are actually predacious. The growth of the fungi generally involves two phases; vegetative and reproductive.  DISTINCTIVE PROPERTIES Mycotic infections are classified by the tissue levels that are colonized. Superficial infections are generally limited to the outer layers of the skin and hair. Cutaneous infections are located deeper in the epidermis, hair and nails. Subcutaneous infections involve the dermis, subcutaneous tissues and muscle. In addition, mycotic infections may be systemic, generally originating in the lungs and other organs. Finally, some mycoses are termed opportunistic, and these may involve a variety of body sites. The following outlines these different types of mycotic infection, giving examples of representative agents.  Superficial infections Superficial: Limited to outer layers of skin and hair Causative agents: Pityriasis versicolor (skin) Tinea nigra (skin) Black/white piedra (hair) Malassezia Exophiala Piedra/Trichosporum  Cutaneous infections Cutaneous: Involves deep epidermis and keratinized body areas (skin, hair, nails). Diseases are generally cosmetic, not life-threatening. Diseases of the skin are termed Tinea Diseases of hair and nails are termed Dermatophycoses. Causative agents: Trichophyton Microsporum Epidermophyton  Subutaneous infections Subcutaneous: Involves dermis, subcutaneous tissues and muscle. Fungi are generally implanted in skin; fungal growth produces a lesion. Causative agents: Lymphocutaneous sporotricosis, Chromoblastomycosis Eumycotic mycetoma Sporothrix Pseudallescheria  Systemic infections Systemic: Originate in lungs Most primary infections are inapparent. Progression may produce pulmonary symptoms or ulcerative lesions. Host responses produce formation of fibrous tissue, granulomas and calcified lesions. Representative organisms are dimorphic Histoplasmosis: most infections are asymptomatic. Cryptococcus Histoplasma capsulatus Blastomyces dematitidis Paracoccidioides braziliensis Coccidioides immitis Cryptococcus neoformans  PATHOGENESIS Mycotic disease is often a consequence of predisposing factors including age, stress or other pathologic conditions (e.g. cancer, diabetes, AIDS). Only the dermatophytes (Trichophyton, Microsporum) and Candida are communicable from human to human. The other agents are acquired from the environment (plants, soil, etc.). Fungi generally cause one of three distinct tissue responses; chronic inflammation (scarring, accumulation of lymphocytes) granulomatous inflammation (collections of modified epithelial cells, lymphocytes) acute suppurative inflammation (vascular congestion, exudation of plasma, accumulation of PMNs).  HOST DEFENSES Host defenses against the fungi include nonspecific and specific factors: Nonspecific defenses include the skin (lipids, fatty acids, normal flora), internal factors (mucous membranes, ciliated cells, macrophages), blood components, temperature, genetic and hormonal factors. Specific defenses include both humoral and cell-mediated.  CONTROL Sanitary: Control by sanitary means is difficult, but the incidence of communicable disease can be reduced by good hygiene. Immunological: No vaccines are currently available. Chemotherapeutic: Many antifungals are available but some are very toxic to the host and must be used with caution. Topical powders and creams often contain tolnaftate or azole derivatives (miconazole, clotrimazole, econazole) and are useful against superficial dermatophytes. Sporotrichosis may be treated using potassium iodide or Amphotericin B Systemic infections are generally treated by Amphotericin B , 5-fluorocytosine (5-FC), miconazole, Fluconazole or ketoconazole. IF YOU HAVE ANY QUESTIONS, KINDLY CONTACT: Dr. Nur Ayunie Zulkepli Center for Medical Laboratory Technology Studies [email protected]