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MYCOLOGY MYCOLOGY The fungi are eukaryotic organisms growing as a mass of branching, interlacing filaments known as mycelium. Among the many thousands of fungi known, only about 300 can cause diseases in humans and animals. Bacteria plant Comparison of fungi and bacteria feature fungi bacteria diameter 4um 1um nucleus Eukaryotic prokaryotic cytoplasm Mitochondria and endoplasmic reticulum present Mitochondria and endoplasmic reticulum present Cell membrane Sterols present Sterols absent Cell wall chitin peptidoglycan spores Sexual and asexual spores for Endospores for survival, reproduction not for reproduction Thermal dimorphism yes No metabolism Require organic carbon; no obligate anaerobes May do not require organic carbon; many obligate anaerobes Structure of fungi Morphology Unicellular fungi Multicellular fungi Hypha: mycelium (vegetative, aerial or reproductive). Spores: asexual spore a) Conidium(分生孢子): macroconidium, microconidium. b) Thallospore(叶状孢子): blastospore(芽生), chlamydospore(厚 膜),arthrospore(关节). c) Sporangiospore(孢子囊孢子) Unicellular fungi Unicellular fungi Multicellular fungi Multicellular fungi Multicellular fungi Hypha •spore Culture Sabouraud culture medium optimal pH 4-6 optimal temperature 22-28 C some deep pathogenic fungi need 37 C, Aerobic types of colonies– yeast, filamentous Multiplication:budding, hypha formation, branching or disruption of hypha, spore formation Resistance Resistant to dry, sunlight, UV light and many chemicals Sensitive to wet heat Clinical manifestations pathogenic fungal infection Opportunistic pathogenic fungal infection Fungal allergic diseases Mycotoxicosis Mycotoxin and tumor Immunity Nonspecific immunity Specific immunity Microbiological diagnosis Specimens Direct smear Isolation and cultivation Serological tests. Fungi of superficial keratinized infection Malassezia furfur(秕糠马拉 癣菌). Fungi of skin infection The most important are dermatophytes, a group of closely fungi classified into 3 genera: Trichophyton(毛癣菌) Epidermophyton (表皮癣菌0 Microsprum(小孢子癣菌) Invade only skin, hair, and nails. Fungi of subcutaneous infection Chromomycosis (caused by several species of black molds; Fonsecaea edrosoi, Cladosporium carrionii, Phialophora verrua have been isolated most frequently). Fungi of deep infection Cryptococcus neoformans Histoplasma capsulatum Coccidioides immites ( 厌酷球孢子菌〕 Blastomyes dermatitides (皮炎芽生菌〕 Paracoccidiodes brasiliensis (巴西副孢子菌〕 Cryptococcus neoformans Oval , budding yeast surrounded by a wide polysaccharide capsule Cryptococcus neoformans Cryptococcus neoformans cryptococcosis No human to human transmission Infection follows inhalation of the cell of C. neoformans, which , in nature , are thought to be small , allowing the organism to enter deep into the lung. Opportunistic Mycoses Candida(假丝酵母菌) Aspergillus (曲霉) Mucor(毛霉) Pneumocystis carinii(卡氏肺孢菌) Candida albicans Etiological agents C.albicans C.guilliermondi C.stellatoidea C.krusei C.tropicalis C.glabratat C.parapsilosis C.viswanathii C.kefyr* C.lusitaniae Clinical categories Cutaneous: intetrigo,paronychia,onychomycosis Mucocutaneous: perleche, thrush, perianal disease Chronic: mucocutaneous candidiasis, guanulomatous disease Systemic: fungemia ,endocarditis,pulmonary infection,urinary tract infection, meningitis, endophthalmitis Yeasts Round to oval, single cells which reproduce by budding Yeasts Candida Cryptococcus Candidiasis Candida albicans Ecological Niche Candida Albicans Endogenous Infections with Candida usually occur when there is some alteration in: Cellular immunity Normal Flora Physiology CANDIDIASIS Skin Vaginitis Urinary tract Mucous membranes Septicemia Endocarditis Pneumonia CANDIDIASIS The fourth most common nosocomial bloodstream infection. Clinical Specimens Candida Sputum Scrapings from lesions Blood smears Vaginal discharge Urine Feces Candida albicans 8-12 MICRONS Pseudomycelium GERM TUBES GEOGRAPHIC OCCURENCE WORLDWIDE Therapy Amphotericin B Nystatin Ketoconazole Fluconazole Itraconazole Cryptococcosis Cryptococcus neoformans Cryptococcosis A sub-acute or chronic infection which may affect the lungs or skin but most commonly manifests as a meningitis Ecological Niche Cryptococcus neoformans • pigeon droppings • Chicken droppings Specimen of choice Cerebrospinal fluid GEOGRAPHICAL DISTRIBUTION WORLDWIDE Clinical Specimens Cryptococcosis •CSF •Sputum •Pus •Biopsy material •urine Serological Tests Cryptococcosis •Indirect fluorescent antibody •Tube Agglutination •Latex Agglutination (measures antigen) Drugs of Choice Cryptococcosis •5-Fluorocytosine •Amphotericin B