Mycology, Protozoa- Study Guide.pdf

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McGill University
Microbiology and Immun (Sci)
MIMM 212
Samantha Gruenheid

PenName’s MIMM211 Study Guide for MIMM211 I, PenName from McGill Open Course, hereby declare that all the resources between are true in content and are gathered from McGill’s MIMM211 Introduction to Microbiology course. If the information below has violated any University policies, I would eradicate this from the internet permanently. Introduction to Mycology Lectures Overview 1. Introduction • Terms • Taxonomy • Life cycles 2. Medical Mycology • Endemic mycoses • Candida and Cryptococcus • Mold infections 3. Toxins and biosynthesis 1941: First case used in penicillin antibiotic is isolated from penicillium fungi (ex. Green Orange) Rhizopus oryzae - Invasive mold, very aggressive - Requires exogenous iron - More frequent in diabetics and iron chelation therapy - Highly drug resistant What are Fungi? 1. Eukaryotic – true nucleus 2. Cell walls – composed predominately of chitin not cellulose/lignin like plants 3. Reproduce by spore formation – asexually(mitosis) or sexual(meiosis) via wind 4. Unicellular (ex. Yeast) and multicellular structures (hyphae/mycelium) 5. Heterotrophic – can’t make their own food (ex. Grow well in dark) Differ from Plants - Cell wall composition (chitin in fungi cell wall) - No photosynthesis, chloroplasts (can’t make own food) - No vascular structures (no complicated organelles) - Glycogen not starch - Genetic analyses – closer to animals Differ from animals - Non-motile (exceptions) - Spit out enzymes to digest then absorb – exophagous (recyclers) - Ergosterol not cholesterol (structural component of cell wall) - Asexual reproduction (fungi usually have both sexual for taxonomical classification and asexual for classication of structures) - Nucleus is small with minimal repetitive DNA - Importance of Good Fungi - Biodegradation – can decompose all organic material - Industrial production – enzymes, antibiotics, and other pharmaceuticals (cyclosporine) - Food industry – mushrooms, yeast (fermentation) and cheese Bad Fungi - Infection – invasive and superficial mycoses (Lecture 2) - Intoxication – aflatoxicosis, ergot alkaloid, toxic mushrooms - Allergy – asthma, sinusitis - Degradation of anything Success of fungi (everywhere and efficient reproduction) - Spores – dispersion (high rate of mutagenesis) and stability (hydrophobic). 1 Petri dish 12 may produce 10 spores after 48-70hours. - Genetic plasticity = adaptability – sexual and asexual, mobile genetic elements, and haploid genomes (often) - Heterotrophism How Successful? 90,000 known fungal species, and approx. 1,700/yr discovered. There’s a 6:1 ratio of fungi to plants. 1.5 million Fungal species is possible for the whole world. Fungal adaptation which grows on the jungle floor – cordyceps (infect ant brains to climb and grow out of its head and wind brings the spores out). Note: they must disseminate to new areas. Some Definitions: - Hyphae – filamentous tubular structure with internal septae and multiple nuclei - Mycelium – group of hyphae (multicellular vs. Single cell. Septase do not close completely and contiguous cytoplasm, so one “cell”.) - Thallus – body of fungi being a “one” living cell. - Yeast – unicellular cells that reproduce by budding Know the structure of septae and the types of septae in Hyphae Taxonomy classified by reproduction mostly. Domain > Kingdom > Phylum > Class > Family > Order > Genus 1) True Fungi (Phyla) - Zygomycota - Ascomycota - Basidiomycota - Chytridiomycota - “Deuteromycota”  no idea where they belong because never seen the reproduction. 2) Slime molds (not gonna mention) 3) Microsporidia 4) Water molds (not going to be mentioned) – Oomycota (now classified as parasites) Asexual reproduction (Anamorph) - Binary fission, “duplication” - Budding (yeast) also “duplication” - Spore production o Arthrospores o Conidia o Sporangiospores o Chalamydospores Note: Know spore production really well!!! Sexual Reproduction (Teleomorph) - Homothallic(reproduction with same organism. May mate from same thallus) - Heterothallic (2 different types/organisms). Types of Spores: - Ascospores - Basdiospores - Zygospores - Zoospores (chytrids) - Oospores (water molds) Chytrids (usually aquatic and non-motile) - Asexual and sexual spores are flagellated and motile - Batrachochytrium dendrobatitidis has been implicated in the declime of frog populations - Zygomycetes (no septae)  very efficient producers (has asexual and sexual spores) - Asexual spores(sporangiospores) are borne within an enclosed sporangium - Sexual spores are zygospores. Pilobolus (zygomycete that grows in cow dung) - Has hydrostatic cannon (which aims by bending stalk directly at the sun), which shoots out spore pockets into unsoiled grass. - 0-45mph in the first mm of flight - Fly up to 6 feet high and 8 feet laterally. Note: Solar sensor is at the bottom of the sporangiphore. Ascomycetes – Life cycle - Many imperfect fungi likely ascomycetes - Asexual spores are unenclosed and termed conidia - Mostly medically important fungi Important Asocarp! Figure 1 Apothecium Figure 2 Perithecium Figure 3 Cleistothecium Asocarp is absent in some (i.e. S. cerevisiae) Basidiomycetes – mushrooms! Gills and pores for reproduction! - Produce complex fruiting bodies containing basidiospores - Increases dispersion by increasing surface area and elevation - Gills, pores or folds Figure 4 Gills Figure 5 Pores Figure 6 Folds Intro to Mycology II Predaceous Fungi - Most deuteromycetes, and one basidiomycete. - Live in soil and often in symbiosis with plants, may be protective - Eat nematodes – microscopic roundworms that are often pathogenic to plants - Product elegant sticky traps. - Some traps have rings (non-constricting and constricting loops that crushes whatever nematodes that swims through it) Pathogenesis - Induction of traps - Trapping - Immobilization - Death - Hyphal invasion - Digestion from the inside out Medical and Pathogenic Mycology 1.) Hypersensitivity – Fungi digest outside of cell. Pump out enzymes(proteins). Allergens are also proteins. Most people have mold allergies. a. Fungal antigens are common precipitators of allergic disease b. Evoke an IgE hypersensitivity response with mast cell degranulation and histamine release c. Asthama, rhinitis, pneumonitis and sinusitis d. Many types of mold implicated but Aspergillus species are excellent examples Aspergillus allergic disease – farmers lung  mold grows on grain and air can be green sometimes because of the amount of endospores. - Decomposing hay has very high content of thermophilic bacteria and fungi - Acute hypersensitivity pneumonia from massive antigen inhalation - Many other occupational versions many due to other fungi. Asthma - Uncomplicated asthma usually due to sensitization to conidial antigens of Aspergillus - Usually controllable with medications and exposure Allergic Bronchopulmonary Aspergillosis - Pre-existing airway disease such as CF - Colonized with A. Gumigatus - High titers of IgE antibody to hyphal antigens - Severe reactive airway disease - Progressive and destructive airways disease Note: Mold induce Asthma – AVPA. Fungus live in the lungs. IgE levels elevates and antigens reproduced. Tissue destruction and only happens to 10% of the people. Mast Cell Degranulation IgE transforms to exterior. By 90mins, the hyphae just by touching the mast cell makes them degranulate (non-allergic asthma) Mast Cell (infective of Asthma) Degranulation (release) _____________________30 mins___________________ _______90 mins______ B) Mast cells with hyphae C) regular mast cell alone 2.) Infection Invasive Disease: Clinical Classification a. Yeasts(unicellular like bacteria) – Systemic disease, pulmonary disease absent or subclinical b. Dimorphic fungi – primary pulmonary disease with dissemination prominent part of disease (alternative forms between molds and yeasts) c. Molds – primary pulmonary disease with diseemination less common. Having sexual and asexual structures, and are very nasty because their endospores take over body tissues. Yeasts: Candida albicans - Grows as yeast, mold, hyphae, pseudohyphae (major virulence factor) - Morphological switching is required for virulence - Normal commensal of humans - Sexual cycle still cryptic although evidence for mating during infection has recently found Candidiasis - OPC (thrush) – superficial infection or oral mucosa - Vaginitis – vaginal mucosa - Skin and nail infections – superficial infection of keratinized squamous epithelium - Hematogenous disseminated disease – invasive disease of endothelial cells and penetration of deep organs (e.g. liver, spleen) Mechanism explained (antibiotics given): - Colonization and/or overgrowth - Breach of integument – Gl or Catheter - Entrance to Bloodstream (ex. Gut) - Germinates in bloodstream (TH1 response) - Evasion of soluble factors and PMNs, which are factors that kill it - Endothelial cell adherence and invasion, gets phagocytozed, grabs cell and kill. - Tissue invasion and evasion of host responses, causing disease st nd Summary: Be aware of the 2 yeast pathogens. 1 can be yeast, become hyphae. 2 can cause thrush, and there’s a mechanism shown. Antibiotics kills everything except yeast. Hole to gain access to bloodstream. Entrance to bloodstream with endospore. It germinates, and it gives a TH1 response. It forces the TH2 response, which is non-protective. Evasion of soluble factors. It attaches to the endothelial cell adherence and invasion, and that’s how it causes disease. Als proteins – analogous to antibodies - Cell Wall proteins anchored to cell wall by C-terminus of the protein - At least 10 in the genome, variable in number - Very similar in sequence, vary only in small regions in N-terminus  generating diversity - Structurally similar to immunoglobulins - Exhibit substrate specific adherence properties dependent on the composition of the N- terminal variable regions - At least one is involved in host cell invasion Antibodies recognize incoming pathogens. Als proteins generate variety, and it is specific that binds to humans. Als3 – great at attaching epithelial cells Als1 – endothelial cells. Als3 and 1 may switch and hybridize giving specificity to different structures Cryptococcus neoformans. Lives in soil and pigeon droppings. Primary pathogen. - Encapsulated yeast - Recent discovery of sexual cycle – basidiomycete, heterothallic - 2 common variables – neoformans and gatti - Environment: o Soli, particularly associated with bird droppings o Eucalyptus trees Case: Vancouver Island Outbreak - Pneumonia and meningitis in immunocompetent - Australia origin? - Infecting native trees and soil Virulence factors Able to measure in blood and it is thermal tolerant grows at 37, human temperature. Melanin promotes virulence. - Capsule – inhibits phagocytosis - Thermotolerance – permits growth in CSF - Melanin o Anti-oxidant o Resists phagocyte killing - All linked to development regulatory patways – RAS and other MAPkinase pathways that are required for mating Dimorphic Fungi (Endemic mycoses) - Endemic means it’s geographically restricted - Primary fungal pathogens - Geographically restricted in range - Classically dimorphic – environmental and infecting form differ o Histoplasma casulatum o Coccidioides immitis o Paracoccidioides brasiliensis o Blastomyces dermatiditis o Penicillium marneffei Endemic Mycoses - Yeast form o Parasitic form o Tissue form o Cultured at 37 - Mycelial form o Saprophytic form o Cultured at 25 Histoplasmosis  origin in South America. Grows in intestine of bat and bat crap. In 1963, only Jewish men were infected with histoplasmosis, but Jewish culture don’t dig.’s because people were digging near the Jewish neighbourhood for the Montreal Metro station. Jewish woman cooks in the house with windows closed. Histoplasmosis Reservoirs - Soil organism – grows as mycelia - Also carried by bats – high concentration in bat guano, bat caves - Thrives in soil enriched with droppings - Sporulates in soil and when soil is disturbed conidia travel with dust - Filamentous and yeast form Histoplasmosis Infection - Humans infected by inhalation of airborne spores - Pulmonary infection similar to tuberculosis - Most resolve, a subset will disseminate - Remains latent for decades and can reactivate if host is immunosuppressed - Treatment usually successful unless advanced disease or comorbidity White Nose Syndrome – Geomyces destructans in bats. Infecting caves where bats hibernate in NE USA. 90% colonies of bats die, over 1million bats have dead. 2.4 million pounds/year of bugs not eaten. Critical reason that we should care is because bats are important pollinators and pest controls. Avocado trees are pollinated by Bats. 3.) Mycotoxicosis – production of toxin in vivo 4.) Mycetismus (mushroom poisoning) – pre-formed toxin 5.) Sick building/Toxic mold Intro to Mycology III Opportunitistic Molds - Immunosuppressed patients ONLY - Pulmonary infection by inhalation of airborne apores with subsequent dissemination - Very aggressive, destructive - Aspergillus most common (>80%) o Aspergillus fumigates most common - Others o Rhizopus, Absidia, Mucor (Zygomycetes) o Penicillium o Pseudallescheria boydii Aspergillus fumigates - Ubiquitous mold - Found on decaying material/soil - Produces large amount of airborne conidia - On average at least 100 conidia are inhaled daily - Sexual cycle newly described – ascomycete Spores germinate and are completely 1hydrophobic because they are covered by Rod A. This fungus can devour the lung without bloodstream, and it is a very hard bacterial infection to treat. Gliotoxin  induce Apotoxins to tells cells to kill themselves. - Secondary metabolite of A. Fumigates - Produced in ug quantities during infection - Cytotoxic - Inhibits NF-kappa B signalling o Prevents neutrophil and macrophage activation and chemotaxis o Blocks TNF production o Induces apoptosis of leukocytes - Mutants deficient in gliotoxin are hypovirulent in mouse model Histopathology – gliP mutants accounts for 5% of disease. Subcutaneous Mycoses (tropical fungus): Chromoblastomycosis - Multiple fungi – dematiaceous molds - Usually traumatic inoculation - Relatively superficial and non-destructive - Natural history is years of infection - Diagnosis by “sclerotic bodies” - Elephant: The skin proteins that drain fluid out of your leg are all blocked by the fungus. Eumycotic Mycetoma - Distinguish from actinomycotic mycetoma - Usually traumatic inoculation - Invasive and destructive - Superinfection common - Diagnosis by “granules” Plant infections - Fungi are the most common cause of plant disease - Enormous economic losses annually - Wide variety of plants affected o Apple scab o Corn smut o Mildew o Wheat rust Dutch Elm Disease (common like Maples in Montreal) - Ophiostoma sp. - Spread by bark beetles as it burrows - Invades wood and sporulates in burrows to be picked up by beetles - Devastated North America elms: 119,000 mature elms died in 3 years in Chicago - Elms are joined together by root systems which promotes the epidemic Maple Presentation: - Red Leaves (Sugar maple – Native) – less susceptive - Yellow Leaves (Norway maple) – susceptible to Rhytisma sp. (Tar spot fungus) Great Irish Famine 1845-1850 (Not fungus anymore) - 1 million deaths and 1.5million emigrated - Population of Ireland decreased by 1/3 in 5 years Potato Blight - Irish landholders were dependent on potato as main source of food - Phytopthora infestans infection of potato’s ruined vast majority of crop - Water mold infection produces stunted rotted potatoes - Intense cultivation made spread of spores highly efficient Toxins and Biosynthesis: Gosio’s Disease - 1891 Dr. Gosio in Italy became concerned by large number of deaths in children - Discovered an association with wallpaper - “Scheele’s green” wallpaper pigment contained arsenic - Grew bread mould with Scheele’s green pigment on paper and found toxic arsenical gases released that could kill a rat - Mold is responsible because of the humidity near the coasts of Italy - Concluded the case of Napoleon’s Death This Iceman also has Fomes Fomentarius, “Tinder Fungus”, and he/she has used an antibiotic to treat infection. Secondary metabolites Eastern territories sell region rights to have people gather cordyceps, in Himalayan Viagra. 1Kg = 1,500,000 USD. Powder cordyceps helps with high altitudes. Fungi lives in nutrient soup and gets anything out of there. Know the antibiotics, and their functions. - Pharmaceuticals o Long history of human use of fungi as medications o Of 20 best selling drugs in 1995, six were fungal metabolites - Toxins - Enzymes Antibiotics - Fungi compete with bacteria - Elaborate large numbers of compounds to inhibit competition o Antibacterials  Penicilin and cephalosporins  Aminoglycosides o Antifungals  Amphotericin  Griseofulvin  Echinocandins (Kills fungi) Other Products - Immunosuppressive medications o Cyclosporine – tolypocladium inflatum, which affects T cells - Lipid lowering agents o Statins – Aspergillus griseus - Transgenic products from S.cerevisiae o Hydrocortisone o Hepatitis B vaccine o Human papilloma virus vaccine *Cyclosporine was rejected as an antibiotic. 95% of survival in transplantation of kidneys. Statins treat cholesterol and it also is an anti-fungi reagents. Industrial products - Enzymes o Glucoamylase and a-galactosidase from A. Niger o Ligninases for biobleaching of paper (brown to white paper from fungi product) - Acids (ex. Cola) o Citric acids, gluconic acid from A.Niger Food Industry - Mushrooms as food - Fermentation (producing puffy bread instead of hard as rocks biscuits) o Saccharomyces cerevisiae and relatives (make alcohol and 50% will die under own exposure of its alcohol)  Wine, beer, ale, cider...etc.  Converts sugars to alcohol, usually up to 15% at which point microbial growth inhibited - Cheese o Blue cheeses such as stilton are stab inoculated with Penicillium roquefortii o Surface mold ripened ch
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