Lecture1 Medical Mycology INTRODUCTION Dr. Ahmed Abdel-Hadi

Terminology Mycologists: Mycology : is the study of fungi Scientists who study fungi Mycology : is the study of fungi Myco- = fungi -ology = the study of Mycoses: are the diseases caused by fungi Medical Mycology: is the study of mycoses of man and their etiologic agents

What are fungi? I- Somatic structure: 1- Fungi are microorganisms that are eukaryotic, non-motile, non- chlorophyllous. 2- Fungal body is usually filamentous (hyphae, mycelia) or unicellular (yeasts). 3- Some fungi live as plasmodia ( myxomycetes). 4- Cell wall of true fungi is composed of chitin, (as in insects). Others have cellulosic walls. 5- Cell membranes have ergosterol (not cholesterol). 6- Cell contents include cytoplasm, nuclei, ribosomes, golgi apparatus, mitochondria, lysosomes, glycogen, lipids, crystals, vacuoles and endoplasmic reticulum.

mycelium: septate mycelium: non septate Downloded from www.pharmacy123.blogfa.com

Chitin is a polysaccharide composed of long chain of n-acetyleglucasamine.

Filamentous Fungi 1.The basic morphological elements of filamentous fungi are long branching filaments or hyphae, which intertwine to produce a mass of filaments or mycelium 2.Colonies are strongly adherent to the medium and unlike most bacterial colonies cannot be emulsified in water. Downloded from www.pharmacy123.blogfa.com

Downloded from www.pharmacy123.blogfa.com Mycelia & Conidia Downloded from www.pharmacy123.blogfa.com

3. The surface of these colonies may be velvety, powdery, or may show a cottony aerial mycelium. 4. Pigmentation of the colony itself and of the underlying medium is frequently present. Downloded from www.pharmacy123.blogfa.com

Downloded from www.pharmacy123.blogfa.com Colony Morphology Downloded from www.pharmacy123.blogfa.com

Yeasts These occur in the form of round or oval bodies which reproduce by the formation of buds known as blastospores. Yeasts colonies resemble bacterial colonies in appearance and in consistency. The only pathogenic yeast in medical mycology is Cryptococcus neoformans.

Cryptococcus neoformans Yeast colonies Cryptococcus neoformans Mucoid colonies Downloded from www.pharmacy123.blogfa.com

Cryptococcus neoformans India Ink SEM Capsule Downloded from www.pharmacy123.blogfa.com

Yeast-Like 1.These are fungi which occur in the form of budding yeast-like cells and as chains of elongated unbranched filamentous cells which present the appearance of broad septate hyphae. these hyphae intertwine to form a pseudomycelium. 2. The yeast like fungi are grouped together in the genus Candida. Downloded from www.pharmacy123.blogfa.com

Candida Colonies Candida albicans Downloded from www.pharmacy123.blogfa.com

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Downloded from www.pharmacy123.blogfa.com Candida albicans SEM Downloded from www.pharmacy123.blogfa.com

Thermally Dimorphic Fungi These are fungi which exhibit a filamentous mycelial morphology (saprophytic phase) when grown at room temperature 27oC, but have a typical yeast morphology (parasitic phase) inside the body and when grown at 37oC in the laboratory (e.g. Histoplasmosis). Downloded from www.pharmacy123.blogfa.com

Histoplasma capsulatum 27oC Downloded from www.pharmacy123.blogfa.com

Histoplasma capsulatum 37oc Downloded from www.pharmacy123.blogfa.com

II- Mode of living: 1- Most fungi are saprophytic living on dead organisms. They secrete digestive enzymes into the medium, then absorb the nutrients (external digestion, they digest then ingest). 2- Some fungi are parasitic (internal or external parasites) of living plants or animals. 3- Other fungi are symbiotic (mutualistic) e.g. lichens ( fungus + alga) and mycorrhizae (fungus + plant roots). 4- Few are predators that capture nematodes.

Cattle ringworm showing multiple crusting lesions. 391. Cattle ringworm showing multiple crusting lesions. T. verrucosum was isolated. (Slide 391 Courtesy Dr Kral, University of Perugia, Italy; Slide 392 Courtesy C.V.L. Weybridge, England). - Tinea barbae in man Cattle ringworm showing multiple crusting lesions. - T. verrucosum was isolated Fungal spores

Plant Pathogenic Fungi

Lichen Anatomy

III- Occurrence: (everywhere) 1- Indoor Air (homes, schools, hospitals, caves, offices, air conditioning filters,….) 2- Outdoor Air (open air, fields, gardens) 3- Fresh and marine water, aquatic animals e.g. fish and fish eggs. 4- Soil (rhizosphere soil) and plant roots 5- Vegetation (leaves, stems, flowers, fruits of plants), wood, paper, carpets etc. 6- Stored seeds, food, fruits, vegetables. 7- Animal dung, bird dropings, wastes

Occurrence: (continued) 8- Keratinaceous materials (hair, skin, nails, hooves, bird feather) 9- Insects and arachnides, nematodes 10- Fungi ( mushrooms, Rhizopus) 11- Some pathogenic fungi are adapted to humans (anthropophilic) and animals (zoophilic). 12- Some fungi tolerate extreme conditions of temperature, pH and water activity

IV- Reproduction: 1- Vegetative: a- Fragmentation of mycelium b- Fission of yeast cells c- Budding of yeast cells 2- Asexual spore formation: a- sporangiospores inside sporangia ( if motile: zoospores in zoosporangia) b- conidia on conidiophores (DTR)

Fission yeast: Schizo- Saccharomyces octosporus

Budding yeast Saccharomyces cervisiae

A c b Asexual spore formation: a- sporangiospores inside sporangia b- zoospores in zoosporangia c- conidia on conidiophores

3- Sexual spore formation: (involves plasmogamy, karyogamy, and meiosis) Kinds of sexual spores: a- Oospores: (1 to several inside oogonium) formed by contact of antheridia and oogonia b- Zygospores: naked, multinucleate, thick walled spores formed by fusion of gametangia (+ & -) c- Ascospores: ( 8 inside each ascus) formed by Contact of antheridia and ascogonia d- Basidiospores :( 4 on each basidium) formed after: - Clamp connections - Spermatization - Somatogamy

Oogonium Oospore Gametangia Zygospore Antheridium Oospores zygospores

8 ascospores inside each ascus 4 basiospores outside each basidium Basidiospores 4 basiospores outside each basidium

VI- Economic importance of fungi: a- Positive role: 1 – Food:Edible mushrooms, morels and truffles used as food. 2 – Biotechnology: Processing good quality of bread (bakery yeast) , cheese (roqueforti and camemberti) and other kinds of food (tempeh). 3- Vitamins (by yeasts) & mycoproteins (Fusarium) 4- Traditional medicine: in China, Cordyceps sinensis and Coriolus versicolor are used to strengthen the body immune system of tumor patients

5 - Production of medically and industrially important compounds such as: - Antibiotics: penicillin, cephalosporin, fusidin and griseofulvin - Immunosuppressive agents: cyclosporine - Cholesterol lowering agents: simvastatin - Antallergic: Corticosteroids. - anticancer compounds from Coriolus versicolor - Organic acids ( citric , gluconic, oxalic, fumaric,..) - Alcohols (ethanol) and glycerol. - Hydrolytic enzymes ( proteases, cellulases, pectinases, lipases , amylases, …etc.)

6 –Improving soil fertility: fungi are important decomposers & recyclers of nutrients in the environment . 7- Better plant growth and higher productivity: Some fungi form symbiotic mycorrhizal associations with roots of several plants . 8- Biocontrol agents : Certain fungi are used to control harmful insects, nematodes, weeds, and even other fungi.

b- Negative role: 1- Several fungi deteriorate food of man and feedstuffs of animals and birds. 2- Others produce harmful hallucinogenic, carcinogenic or deadly toxins. 3 - Destructive plant diseases are caused by several air or soil borne fungi (blights, mildews, rusts, smuts, rots,...) 4 – Many fungi are involved in allergy as well as superficial, subcutaneous or systemic diseases of man, animals and birds. 5- Certain fungi attack fish and their eggs , others are harmful to benificial insects as silkworms and honey bees.