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MYCOLOGY

MYCOLOGY. Xiao-Kui Guo PhD. Classification. Based on molecular evidence: base sequences from ribosomal RNA (Patterson & Sogin 1992). Comparison of fungi and bacteria. Medically important fungi. Includes 4 phyla

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MYCOLOGY

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  1. MYCOLOGY Xiao-Kui Guo PhD

  2. Classification Based on molecular evidence: base sequences from ribosomal RNA (Patterson & Sogin 1992)

  3. Comparison of fungi and bacteria

  4. Medically important fungi Includes 4 phyla • Ascomycota（子囊菌门）- Sexual reproduction in a sack called an ascus with the production of ascopspores. • Basidiomycota（担子菌门）-Sexual reproduction in a sack called a basidium with the production of basidiospores. • Zygomycota（接合菌门）- sexual reproduction by gametes and asexual reproduction with the formation of zygospores. • Mitosporic Fungi（Fungi Imperfecti，半知菌门）- no recognizable form of sexual reproduction. Includes most pathogenic fungi.

  5. Structure of fungi

  6. 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）

  7. Multicellular fungi Hypha • spore

  8. Hypha

  9. Dimorphism （二相性真菌）

  10. 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

  11. Resistance • Resistant to dry, sunlight, UV light and many chemicals • Sensitive to wet heat

  12. four types of mycotic diseases: • Hypersensitivity - an allergic reaction to molds and spores. • Mycotoxicoses - poisoning of man and animals by feeds and food products contaminated by fungi which produce toxins from the grain substrate. • Mycotoxin and tumor • Mycetismus - the ingestion of toxin (mushroom poisoning). • Infection

  13. Immunity • Nonspecific immunity • Specific immunity

  14. DIAGNOSIS • 1. Skin scrapings suspected to contain dermatophytes or pus from a lesion can be mounted in KOH on a slide and examined directly under the microscope. • 2. Skin testing (dermal hypersensitivity) used to be popular as a diagnostic tool. • 3. Serology may be helpful when it is applied to a specific fungal disease. • 4. Direct fluorescent microscopy. • 5. Biopsy and histopathology. • 6. Culture.Pathogenic fungi are usually grown on Sabouraud dextrose agar . It has a slightly acidic pH (~5.6); cyclohexamide, penicillin, streptomycin or other inhibitory antibiotics are often added to prevent bacterial contamination and overgrowth.

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