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Mycology.ppt

This document provides definitions and information about fungi and fungal diseases. It discusses the five kingdom system and defines mycologists, mycology, and mycoses. It describes the four broad classes of fungi and explains characteristics like hyphae, mycelium, yeasts, dimorphic fungi, and types of reproduction including asexual and sexual spores. The document discusses the importance of fungi in industries like fermentation. It also covers medically important fungi, describing systemic, subcutaneous, cutaneous, and opportunistic mycoses. Key fungal genera that cause infections are identified.

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Microbiology 205 Georgetta Seidel
Definitions • Mycologists--scientists who study fungi • Mycology--scientific discipline dealing with fungi • Mycoses--diseases caused in animals by fungi
The five kingdom system • Eukarya (includes all organism with a nucleus & membrane bound organelles) • Plants and Animals are fairly obvious • Fungi, are very distinct from the other kingdoms • Kingdom Protista is a “dumping ground” for organisms that don’t fit into the other eukaryotic kingdoms
Exoenzymes are found in fungi and some bacteria. They are digestive enzymes that are secreted into the environment, where they digest the food into small molecules that can be absorbed and used by the fungus.
• FUNGI • 100,000 species • 100 human pathogens, fungi associated diseases are rising, due to nosocomial infections and in immunocompromised patients (ie. HIV, diabetes, lupus, transplant folks) • Aspergillosis, Blastomycosis— pulmonary infections and dissemination may be involved • 5,000 plant pathogens=$1 billion/yr
IMPORTANCE OF FUNGI • Fermentation industry • Remember fermentation is an anaerobic process - Wine (yeast) - Beer - Bread - Cheese (bacteria) - Soy sauce (filamentous fungi (Aspergillus oryzae provides a low protein diet with amino acids, yeast & bacteria) soy beans & flour are held in a container for mold to grow—moldy beans are incubated for several months - Sauerkraut - Vinegar (yeast and bacteria) - Yoghurt (Bacteria)
IMPORTANCE OF FUNGI • Drug manufacturing (usually their waste products are to our benefit) – Citric acid –Ethanol (yeast) –Antibiotic griseofulvin, penicillin – Cortisone (Rhizopus) – immunosuppressive agents (cyclosporine)
IMPORTANCE OF FUNGI (cont.) • SAPROPHYTE •Degrade complex organic materials into simple ones, which become available for other organisms
Importance of Fungi (cont.) • MYCORRHIZAE • Fungi associated with plants Symbiosis • Fungi help plant roots absorb minerals and water in the soil- serve as root extensions • Fungi benefit by absorbing nutrients exuded by plant roots
•They are often called “ancient plants” •4 broad classes exist • Algal fungi • Sac fungi •Imperfect fungi • Club (basidium) fungi
Algal fungi • All are microscopic and grow in water and damp soil • Many species in this group are responsible for blights (like Irish Potato Famine) • Some species, such as Rhizopus however, are used as a source of cortisone and other "drugs"
• yeasts and the blue and green molds often seen on decaying citrus fruits, in jellies and on leather • Some species, like Penicillium are economically useful, but others such as Ergot (Clavicep s purpurea) which infects rye crops, can cause mass destruction • In controlled doses, however, Ergot becomes an important alkaloid used to control hemmorrage (during the birthing process) as well as in the treatment of migraine • Candida albicans is another species of sac fungi that is parasitic in human beings and aids in the normal functioning of the digestive tract Sac fungi
Imperfect fungi • molds that mildew walls and spot clothes, as well as those that cause plant diseases, athlete's foot, and ringworm. • Some of these fungi are useful like Aspergillus, used in the production of miso (fermented soy paste)
Club (basidium) fungi • largest group of fungi which includes rusts and smuts that attack specific plants, such as corn, beans, apples, wheat, asparagus, coffee, roses and barberry • many of the mushrooms in this division are edible and delicious, a large number of them, such as the Amanita's are deadly poisonous
FUNGAL STRUCTURE • Thallus-”body” –Molds & fleshy fungi have these structures •Long filaments of cells (hyphae) •Septate-Cross Wall (Most Fungi) •Coenocytic-No cross wall, continuous mass with many nuclei
MYCELIUM •Intertwined filamentous mass formed by hyphae, visible to the unaided eye •Forms when environmental conditions are right
YEAST Facultative Anaerobes • Fermentation=ethanol and CO2 • Non-filamentous unicellular fungi –Spherical or oval • Reproduction –Two types exist –a)Fission or b) budding
Yeast Reproduction • FISSION • “even” reproduction, nucleus divides forming two identical cells, like bacteria • BUDDING • “uneven” reproduction, parent cell’s nucleus divides and migrates to form a bud and then breaks away
DIMORPHIC FUNGI • Growth as a mold or as a yeast • Most pathogenic fungi are dimorphic fungi • At 37o C yeast-like • At 25o C mold-like • Can also occur with changes in CO2 • Fungi grow differently in tissue vs nature/culture; often dictated by temp
Within Agar=mold, Agar Surface=yeast Changes in CO2
Types of REPRODUCTION • Asexually-fragmentation of hyphae • Asexually and Sexually-spores –Spores: Used for Identification Four groups of true fungi –Zygomycetes (common bread mold— Rhizopus) –Basidiomycetes (puffballs & common mushrooms) –Ascomycetes (Dutch elm disease/rye smut) –Deuteromycetes (fungi imperfecti)
Classification of these groups •First three groups is based on their method of sexual reproduction •4th group, the Deuteromycetes, have NO sexual reproduction
REPRODUCTION (cont.) • Asexual Reproduction • Progeny will be identical to parent –Spores (Conidiospores, Blastospores,Chlamydospores, Sporangiospores) –Hyphae fragmentation (Arthrospores)
IDENTIFICATION OF FUNGI • Examination of asexual spores • **Fungal spores are different than the endospores of bacteria • Endospores are not for reproduction, but an environmentally resistant life stage • Fungal spores are for reproduction, do not ensure resistance to environmental conditions
Asexual spores •Conidiospores •Chlamydospores •Sporangiospores •Blastospores
ASEXUAL SPORES Conidiospore –Multiple (chains) or single spores formed at the end of an aerial hypha –Not enclosed within a sac –Aspergillus spp. –Penicillium spp.
Conidial fungus •reproduces by means of asexual spores called conidia •Conidia vary greatly in shape, size and color •Most of the common household molds & mildews are conidial fungi
ASEXUAL SPORES (cont.) • Another type of Conidiophore: • Blastospores –A bud coming off the parent cell – Candida albicans Blastospore
Blastospores
ASEXUAL SPORES (cont.) • Chlamydospore –Formed within hypha –Thick-walled spore •Candida albicans
Chlamydospores • The chlamydospore is a method of producing a substantial resting spore very quickly • Nutrient is shunted from adjacent cells into a preferred cell and it swells up, converts nutrient materials to oil droplets for efficient storage, then rounds off with a thick, often roughened outer wall for protection
Chlamydospores
ASEXUAL SPORES • Sporangiospores –Hundreds formed within a sac (sporangium) at the end of an aerial hypha –Rhizopus spp.
Rhizopus spp
Chlamydospores Arthrospores Sporangiospores Conidiospores Blastospores 1 3 1A 1B 2
NUTRITIONAL ADAPTATIONS • Acidic pH (5.0) • Most molds are aerobic • Yeasts are facultative anaerobes
NUTRITIONAL ADAPTATIONS (cont.) • High osmotic pressure • Low moisture • Less N2 than bacteria • Complex carbohydrates –Lignin(component of wood) *Saprophytes
MEDICALLY IMPORTANT FUNGI part II
(Some characters used in identification of deuteromycetes)
ALL FUNGI: • are eukaryotes • develop from spores • display neither flagella, cilia, nor chloroplasts • have cell walls (though not necessarily ones composed of cellulose as are plant cell walls, but instead of chitin and other polysaccharides) • Though displaying great variety and complexity, the fungi are routinely divided into two major groups: • the macroscopic (fleshy) fungi • the microscopic fungi (molds and yeasts)
Fungal growth requirements • In contrast to bacteria, fungi tend grow in places that are: – more acidic – have higher osmotic pressures – are lower in moisture – are low in nitrogen – contain complex carbohydrates
Fungal structures Hyphae are one dimensional arrangements of cells. • septa are the cross walls which separate individual cells in hyphae. • Mycelium are a tangled mass of hyphae. • Mycelium can extensively permeate the substrate within which the fungi grows whether it be soil, water, or even living tissue.
Molds vs Yeast • Molds • Molds are aerobic, filamentous fungi including – mildews – rusts – smuts • Molds tend to grow on surfaces rather than throughout substrates. • Yeasts – unicellular/nonfilamentous: • Yeasts are fungi which are: • typically spherical or oval • facultatively anaerobic • They are often observed as powdery coatings on plant material.
Dimorphic fungi •Dimorphic fungi are fungi that behave like molds (multicellular---consist of hyphae) under some conditions, and like yeasts (unicellular--- lack hyphae) under others.
Review
Fungal reproduction • fungi replicate by mitosis rather than the binary fission employed by bacteria. • Types of fungal reproduction, : – budding – fission – hyphae fragmentation – sporulation
Sexual and asexual: Fungal spores come in two varieties: asexual spores and sexual spores – Spores are used extensively to identify fungi. • Asexual spores – asexual spores are formed by a single parental fungi and therefore genetically identical to the parental fungi. – Asexual spores come in a variety of types formed by a variety of mechanisms including: • Arthrospores (sliced bread pieces) • Blastospores (buds on a twig) • Chlamydospores (giant cell with oil) • Conidiospores (fingers) • Sporangiospores (sac)
Ascomycetes • Asexual phase- Conidiospores (Penicillium and Aspergillus & budding yeast •Sexual phase (morels lichens)
Zygomycetes • Asexual phase—Sporangium—bread mold (Rhizopus stolonifer) • Sexual phase--- sporgangium --- shotgun fungus (lives on dung) it shoots its sporgangium explosively towards light or fly pathogen (Entomophthora muscae—--these types of fungi have been used as agents for biological control of insects)
Basidiomycetes • Basidiospore •Examples: boletes, puffballs,smuts, stinkhorns and tooth fungi
DEUTEROMYCETES (cont.) –Aspergillus - Microsporum (dematophytes) –Blastomyces - Penicillium –Candida - Trichophyton –Histoplasma - Pneumocystis ?
Zygomycetes • “saprophytic” molds • common bread mold (Rhizopus) • coenocytic hyphae • Asexual spores: Sporangiospores Approximately 600 species including bread molds (such as Rhizopus) exist
Ascomycetes •“sac” fungi •Septate hyphae and yeasts •Asexual spore: –Conidiospores Approximately 30,000 species including yeasts (Saccharomyces cerevisiae), some of the molds (Aspergillus), morels, and truffles. Ascomycetes have typical reproductive structures called asci.
Basidiomycetes •“club”fungi •Mushrooms Approximately 25,000 species including many macroscopic fungi (mushrooms, puffballs, shelf fungi) as well as a number of plant pathogens (rusts, smuts).
FUNGAL DISEASES •Mycosis: Fungal infection •Usually chronic •Four groups of mycoses based on degree of tissue involvement and mode of entry
TYPES OF MYCOSES •Systemic •Subcutaneous •Cutaneous •Opportunistic Because fungi are slow growing, mycoses are generally long-lasting
SYSTEMIC MYCOSES • Deep within the body –effects a number of different tissues and organs • Usually soil fungi • Spore inhalation=Route of transmission-starts in the lungs and spreads to other body tissues • Not contagious
SYSTEMIC MYCOSES (cont.) • Histoplasmosis • Coccidiomycosis • Coccidioides immitis got renamed for the AZ Valley fever Coccidioides posadasii
SUBCUTANEOUS MYCOSES •Infections beneath the skin •Soil and plant fungi •Hyphae or spores in wounds
CUTANEOUS MYCOSES • Called “Dermatophytes” • Epidermis • Hair • Nails • Secrete keratinase-degrades keratin (protein found in hair, skin and nails) • Contagious-direct contact with infected hairs and epidermal cells
CUTANEOUS MYCOSES •Skin high osmotic pressure •Low moisture
OPPORTUNISTIC MYCOSES •Broad-spectrum antibiotics •Transplant patients •AIDS patients •Cancer patients –Ex: Stachybotrys (mold), Mucormycosis and Aspergillosis
DERMATOPHYTES •Grow on keratin –Hair –Nails •Tinea or ringworm
TINEA •Capitis (scalp)-can lead to bald patches •Cruris (groin) •Pedis (athlete’s foot)
FUNGI IN CUTANEOUS MYCOSES •Three genera involved in cutaneous mycoses: •Trichophyton •Microsporum •Epidermophyton
TRICHOPHYTON • Hair •Skin • Nails (Tinea ungulum)
MICROSPORUM • Hair • Skin
EPIDERMOPHYTON •Skin •Nails
Fungi in Cutaneous Mycoses Trichophyton Microsporum Epidermophyton Hair Hair Skin Skin Skin - Nails - Nails
Tinea capitis Tinea capitis Tinea barbae
Tinea cruris
Tinea unguium Tinea pedis
SUBCUTANEOUS MYCOSES • More serious than cutaneous mycoses • Sporothrix schenkii –Soil organism • Gardeners=ulcers on hands
Subcutaneous mycosis (mycetoma)
Mycetoma • Mycetoma is a chronic infection of the skin, subcutaneous tissue and sometimes bone • It is generally found on the foot where it is given the name watering can foot • Mycetoma may be due to several fungi or actinomycetes (actinomycetoma). • Actinomycetes are bacteria producing filaments like fungi. Both the fungi and the actinomycetes are found in soil and plant material in tropical regions. • The organism is inoculated into the skin by a minor injury, for example, a cut with a thorn when barefoot.
Mycetoma—a deep fungal infection
Clinical features • Mycetoma is more common in men than women, particularly those aged 20 to 50. It generally presents as a single lesion on an exposed site and may persist for years. • It starts as a small hard painless lump under the skin. • It grows slowly but eventually involves underlying muscles and bones. • The middle of the lesion caves in, ulcerates and discharges pus, which contains grains. • Eventually, sinus tracts (holes) develop which also discharge pus and grains. • The surface skin is scarred and pale. • Considerable deformity often makes it difficult to walk. • Mycetoma may cause no discomfort but it often itches or burns. • Secondary bacterial infection is common. • Treatment is slow
CANDIDIASIS •Mucosal normal microbiota suppresses the growth of Candida albicans
CANDIDIASIS (cont.) • Vaginitis and thrush are initiated by: –Antibiotics eliminate normal microbiota –pH changes • Infants that may not have their normal microbiota established=thrush
Candidiasis Thrush Vaginal
CANDIDIASIS (cont.) •Hematogenous dissemination •Kidney •Spleen •Lung •Liver