Experiment eight Medical Mycology ---Fungi

Introduction Fungi Fungi are eukaryotic microorganisms that possess a cell wall and a nucleus enclosed by a nuclear membrane, and they do not contain chlorophyll.

Medically important fungi Includes 4 phyla Ascomycota （子囊菌门） - Sexual reproduction in a sack called an ascus with the production of ascopspores. 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. 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. 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. Mitosporic Fungi （ Fungi Imperfecti ，半知菌门） - no recognizable form of sexual reproduction. Includes most pathogenic fungi.

A. Size: –several to tens times larger than bacteria B. Two basic morphological forms –Yeast: monocellular fungi Yeast form fungi Yeast form fungi Yeast-like form fungi (Candida albicans) Yeast-like form fungi (Candida albicans) –Mold: multicellular fungi Hypha + spore Hypha + spore I. Morphology

Yeast Monocellular fungi Monocellular fungi Round or oval Round or oval Reproduce by budding/fission Reproduce by budding/fission Pseudohypha Pseudohypha budding Pseudohypha

Mold Multicellular fungi Multicellular fungi –Hypha –Spore –Fungi identification

Hypha

spore hypha

Hypha Hypha –branching, threadlike filaments of fungi that elongate at their tips septate hypha \ coenocytic hypha septate hypha \ coenocytic hypha –3 kinds of hypha Vegetative hypha Vegetative hypha Aerial hypha Aerial hypha Reproductive hypha: Reproductive hypha: aerial hypha that produce spores Mycelium Mycelium –The complex of a mass of hypha

II. Culture Culture medium: Culture medium: Sabouraud’s agar (4% glucose, 1% peptide, 2% agar) Sabouraud’s agar (4% glucose, 1% peptide, 2% agar) 22~28 ℃, pH 4~6; 22~28 ℃, pH 4~6; High moisture and O 2 ; High moisture and O 2 ; Fungal colony Fungal colony a. Yeast colony, e.g., Cryptococcus neoformans. b. Yeast-like colony, e.g., Candida albicans. c. Filamentous colony, e.g., mold

Yeast colony Round, pasty/mucoid creamy, opaque colonies similar to bacterial colony

Candida albicans Yeast-like colony

Filamentous colony Mold colony Penicillium colony

Round, capsule, 3~5  m Round, capsule, 3~5  m 4~7  m in diameter 4~7  m in diameter blood agar and Sabouraud’s agar 25 ℃ & 37 ℃ blood agar and Sabouraud’s agar 25 ℃ & 37 ℃ nonpathogenic cryptococcus cannot grow at 37 ℃ nonpathogenic cryptococcus cannot grow at 37 ℃ yeast form colony yeast form colony Cryptococcus neoformans Cryptococcus neoformans

Examine fungi of the skin Direct examination Direct examination Material: scissors, sterile tweezers,slides, Material: scissors, sterile tweezers,slides, lid slides,10%KOH. lid slides,10%KOH. Procedure: Procedure: 1.Make a smear: take some skin tissues from the foot on the slide. Drop 1 drop of 10%KOH solution to the skin. Wait for a while. Put the lid slide on the skin tissues and heat slightly. 1.Make a smear: take some skin tissues from the foot on the slide. Drop 1 drop of 10%KOH solution to the skin. Wait for a while. Put the lid slide on the skin tissues and heat slightly. 2.Direct examine with the microscope. 2.Direct examine with the microscope.

Culture: Culture: Culture medium: Sabouraud medium Method: streak plate 22~28 ℃,incubate 1~7 days Detection of colony Gram-stain