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Unformatted text preview: Lecture 15: Medical Mycology Fungi: Widely distributed in nature (air, water, soil, decay) Facultative anaerobes/strict aerobes Gets nutrients by absorption Mushroom is one of the more common fungi (grows into dead trees) Mycelium: balls on the surface of the stalks are spores o Spores are reproductive unit of fungi o Wind blows the spores and spreads then Fungi are ubiquitous o Most common organism in the air we breathe o Those who live in moldy environment are more exposed o NOT spread person to person Fungi are eukaryotes o 80s ribosomes o Membrane bound organelles; Sterols in cytoplasmic membrane o Multiple linear chromosomes Fungal nutrition: o Fungi grow their food o Most often live on bead organic matter o Secrete enzymes that break down complex carbs and proteins o Do NOT photosynthesize Fungal cell wall: (usually beta linked glucose) o Glucan - b (a) linked glucose o Mannan - a linked mannose o Chitin - b linked N-acetylglucosamine Membrae: o Primary sterol is ergosterols rather than cholesterol o Difference is the basis for2 classes of anti-fungal drugs Amphotericin B Widely used Binds ergosterol and destabilizes membrane Imidazole Mycelia : Types o Vegetative: undifferentiated, form early, grow into media o Aerial: bear spores, form later, grow up into the air Classes of Fungi: Yeast: unicellular o Divided by budding Daughter cells significantly smaller than mother o Colony appearance like bacteria (smooth, moist looking) Molds: multicellular o Divide by elong Mold growth by extension of the hyphae tip Form spored or conidia Spores spread through wind Spores are the infectious form In tissues mold reproduces by fragmentation of hyphae (NO NOT FORM SPORES) o Colony is fuzzy o Identicifation of Molds: Requires spore formation (sporulation) Can NOT ID a mold from hyphae in tissue Candida: Cell wall rich in glucan; has less chitin than others Cell wall of Candida albicans the yeast Multi-layered higher structured cell wall with lots of carbs Most common medically important yeast Opportunistic Molds: Small number of environmental molds can cause invasive disease in people Most common is Aspergillus Another is Mucor/Rhizopus Many other molds can cause disease rarely Aspergillus Family Aspergillus fumigatus o Most frequent opportunistic fungus infection Causes &gt;90% of human disease due to molds Causes invasive disease in immunocompromised Allergic disease; fungus ball (see later) o Formation of spores with big aggregation of spores (outside of body) o Inside body no spores; hyphae branching at acute angles o 150 species; has septate hyphae o Most species produce proteinases and glucanases o Colony is gray/green (Smoky= fumigatus in latin) o Why is it more pathogenic than others?...
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- Spring '11