MYCOLOGY（真菌学）

The fungi are eukaryotic organisms 真核细胞型 growing as a mass of branching, interlacing 交错的 filaments known as mycelium 菌丝体 . Among the many thousands of fungi known, only about 300 can cause diseases in humans and animals.

plant

Bacteria

※Comparison of fungi and bacteriafeature fungi bacteria

diameter 4um 1um

nucleus Eukaryotic 真核的 Prokaryotic 原核的

cytoplasm Mitochondria and Golgi apparatus , endoplasmic reticulum present

Mitochondria and endoplasmic reticulum absent

Cell membrane Sterols present 有胆固醇 Sterols absent 有胆固醇

Cell wall Chitin 几丁质 Peptidoglycan, phospholipid

spores Sexual and asexual spores for reproduction

spores for survival, not for reproduction

metabolism Require organic carbon; no obligate anaerobes 专性厌氧

May do not require organic carbon; many obligate anaerobes

Structure of fungi

※A. Morphology and StructureUnicellular fungi ( yeast 酵母菌 )

Multicellular fungi (filamentous fungus 丝状菌 mold 霉菌 )

Hypha 菌丝 : mycelium 菌丝体( vegetative 营养 , aerial 气中 or reproductive 生殖 )

Spores 孢子 : 繁殖结构 sexual spore and 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

Multicellular fungi

Hypha

spore

链霉菌菌丝

小分生孢子

大分生孢子

two main groups: ※yeasts and molds

Yeasts : reproduce by asexual budding 出芽Molds : a. Hypha b. Spore asexual cell division or sexual reproduction Dimorphic fungi 双相性 : Several medical important fungi are dimorphic fungi. They are capable of converting from a yeast or yeast-like form to a filamentous form and vice versa 反之亦然， usually exist in the yeast of yeast-like form in a mammalian body and as the filamentous form in the environment or general media.

B. ※Culture ※ Sabouraud culture medium

沙保培养基 optimal pH 4-6optimal temperature 22-28 ℃ some deep pathogenic fungi need 37 ℃Aerobic 需氧※ types of colonies – yeast filamentous

Unicellular fungi(smooth, soft, compact 紧

凑 )

Unicellular fungi

Multicellular fungi( floc 絮状 , villiform 绒毛状 , dusty 飞扬 )

Multicellular fungi

Resistance

Resistant to dry, sunlight, UV light and many chemicals

Sensitive to wet heat

D. PATHOGENESIS 致病性 Pathogenic fungal infection（浅部感染和深部感染） Opportunistic pathogenic fungal infection

Fungal allergic diseases

Mycotoxicosis 真菌性中毒 Mycotoxin and tumor 真菌毒素与肿瘤

1. Pathogenic fungal infection

For example, dermatophytes 皮肤癣菌( colonizers of the skin, hair, and nails ) elaborate the enzyme keratinase 角蛋白酶 , which hydrolyzes the structural protein keratin.

2. Opportunistic fungal infection

Some circumstance 情况 that lead to infection

the use of broadspectrum antibacterial drugs

Weakness of the host by the use of therapeutic measures (e.g. x-ray irradiation, steroids, and other immunosuppressive 抑制 drugs)

alteration of the host's immune system (e.g. uncontrolled diabetes mellitus 糖尿病 , suppression such as that cause by AIDS).

3. Fungal Allergies Throughout life, the respiratory tract is exposed to airborne 空气传播的 conidia 分生孢子 and spores of many saprophytic 腐生的 fungi.

These particles often possess potent 有效的 surface antigens capable of stimulating and eliciting 引起 strong allergic reactions.

In some cases both infection and allergy may occur simultaneously 同时地 . Depending on the site of deposition 沉积作用 of the allergen, a patient may exhibit rhinitis 鼻炎 , bronchial asthma, alveolitis 齿槽炎 , or generalized 无显著特点的 pneumonitis. Atopic 遗传性过敏症的 persons are more susceptible .

4. Mycotoxicosis

Many fungi produce poisonous substances called mycotoxins that can cause acute or chronic toxicosis and damage.

Mycotoxicosis may result from ingestion of fungal-contaminated foods.

5. Mycotoxin and tumor Aflatoxins 黄曲霉毒素 produced by Aspegillus flavus 黄曲霉 have become known as potent carcinogens 致癌物质 .

E.Immunity

Nonspecific immunitySpecific immunity

Nonspecific barriers to fungal infection must be crossed, however, before specific immune responses to fungi are elicited. These primary barriers to fungal infection include intact skin, naturally occurring long-chain unsaturated fatty acids , and competition with ※normal bacterial flora. In addition the mucous membranes are covered with fluids containing antifungal substances. Furthermore, many epithelial cells of the mucous membranes contain cilia that actively remove microorganisms.

Both humoral and cell mediated immunity (CMI) are important in control of fungal infections, but CMI ※appears to be more important since patients with defects缺陷 in CMI usually suffer more severe fungal infections than do persons with depressed 降低的 humoral immunity.

The cell-mediated immune response is protective; its suppression can lead to reactivation and dissemination 再发和扩散 of asymptomatic fungal infections and to disease caused by opportunistic fungi. Circulating IgG and IgM are produced in response to fungal infection, but their

role in protection from disease is uncertain.

F . Microbiological diagnosis

Specimens

Direct smear

Isolation and cultivation

Serological tests

G. PREVENTION AND TREATMENT

Prevention includes avoidance of environments and conditions conducive to fungal growth.

The drugs used to treat bacterial diseases have no effect on fungal diseases. The effective drugs exploit作用于 the presence of ergosterol 麦角固醇 in fungal cell membranes. These drugs, i.e., amphotericin B and the various azoles.

总 结

真菌属于哪类微生物？与细菌有什么区别？真菌的形态结构特点？真菌的培养特点？真菌致病作用有哪几方面？真菌感染后以何种免疫性为主？

MAIN PATHOGENIC FUNGI

Superficial 表面真菌病 cutaneous 皮肤真菌病 subcutaneous mycoses

皮下组织真菌病 systemic infections

系统真菌病

A ． Superficial Mycoses

表面真菌病

Malassezia furfur （秕糠马拉癣菌） ◆Pityriasis versicolor 花斑癣是由粃糠马拉癣菌感

染皮肤角质层引起的慢性感染 ◆ Discrete, serpentine, hyper- or hypopigmented maculae occur on the skin 皮肤上出现分散、蜿蜒、色素加深或减低的斑点

B ． Cutaneous Mycoses------

Dermatophytes皮肤真菌病 superficial keratinized tissue 角化组织

infection,The most important are dermatophytes （皮肤癣菌） , classified into 3 genera: Trichophyton （毛癣菌）Epidermophyton （表皮癣菌）Microsprum （小孢子癣菌）

Invade only skin, hair, and nails.

1. Distinctive Properties: unable to grow at 37℃ or in the presence of serum .

have developed keratinases 角蛋白酶 , elastases 弹性蛋白酶 , and other enzymes that enable them to be quite host-specific 宿主特异性 .

Dermatophytes are identified by their colonial appearance 菌落外形 and microscopic morphology after growth for 2 weeks at 25 on Sabouraud's agar℃

2. Pathogenesis: infected persons by direct contact. Microsporum 小孢子癣菌属 is also spread from

animals.

A single species → more than one type of infection A single infection → more than one species

clinical manifestation

They can causes tinea pedis 足癣(Athlete's Foot), feet; tinea unguium甲癣 , nails; tinea corporis 体癣 , body; tinea cruris 股癣 , groin; tinea manus 手癣 , hands; tinea capitis 头癣 , scalp hair; and tinea barbae 须癣 , beard hair.

3.Diagnosis:

Scrapings 被刮削下的碎屑 of skin or nail →10% KOH on a glass slide show hyphae 菌丝 under microscopy.

Cultures on Sabouraud's agar at room temperature develop typical hyphae and conidia 分生孢子

C ． Subcutaneous Mycoses皮下组织真菌病

Chromomycosis 广色霉菌病(caused by several species of black molds; Fonsecaea edrosoi, Cladosporium carrionii, Phialophora verrua have been isolated most frequently).

D. Systemic mycoses系统真菌病

（ 1 ） pathogenic fungi→ Cryptococcus ※neoformans 新生隐球菌Oval 椭圆的 , budding yeast surrounded by a wide polysaccharide ※capsule

a ． Distinctive Properties: its ability to grow at 37 ℃

the production of phenol oxidase 苯酚氧化酶

b ． Pathogenesis: Infection follows inhalation 吸入 of the cell,

which , in nature , are thought to be small , allowing the organism to enter deep into the lung.

No human to human transmission

The commonest manifestation is a subacute or chronic form of meningitis （隐球菌性脑膜炎 ）

C. neoformans can be isolated in large numbers from pigeon droppings 粪 in the environment

c ． Diagnosis: Tests for capsular antigen can be performed 测试on cerebrospinal fluid and serum. The latex slide agglutination test 检测隐球菌抗原的乳胶凝集试验 cerebrospinal fluid mixed with a drop of

India ink※ , the yeast cell can be seen microscopically to be surrounded by a wide, unstained capsule.脊髓液与一滴印度墨汁混和后在显微镜下可见厚的、不着色的荚膜

(2) Opportunistic Mycoses→

※Candida （假丝酵母菌）

Others: Aspergillus （曲霉）

Mucor （毛霉）

Pneumocystis carinii( 卡氏肺孢菌）

A. Candida Albicans （白色念珠菌）

Candida albicans （白假丝酵母菌） is a yeast causing candidiasis （念珠菌病） or ※"thrush" （鹅口疮） in humans. ※C. albicans is part of the normal flora of the vagina and gastrointestinal tractAs a superficial mycoses, candidiasis typically infects the mouth or vagina. Antibiotic treatment can also alter the normal bacterial flora allowing C. albicans to flourish 活跃 .

11 ．． Distinctive Properties:Distinctive Properties:

oval, budding yeast cells. also form ※pseudohyphae .

On nutritionally deficient media ， produces large, spherical chlamydospores※厚膜孢子 .

2 ． Pathogenesis: a. Cutaneous and Mucosal Candidiasis:

1.Oral thrush 鹅口疮 can occur on the tongue, lips 唇 , gums 齿龈 , or palate 上颚 . Yeast invasion of the vaginal 阴道 mucosa leads to vulvovaginitis 外阴阴道炎 .

2.Other forms include invasion of the skin. occurs in moist, warm parts of the body such as the axillae 腋下 , groin 腹股沟 . The infected areas become red and moist and may develop vesicles 泡 .

3. onychomycosis 甲癣 .

红斑型白念病

口腔白念病 白念甲沟炎

白念食管炎

b. Systemic Candidiasis:

1. caused by indwelling catheters 留置导管 , surgery, intravenous drug abuse 滥用 , damage to the skin or gastrointestinal tract. 2.Patients with compromised phagocytic defenses 细胞免疫缺陷 may develop occult lesions 隐匿损害 anywhere, especially the kidney, skin, eye, heart, and meninges 脑膜 .

c. Chronic Mucocutaneous Candidiasis: Most forms have onset 发作 in early childhood, are associated with cellular immunodeficiency and endocrinopathies 内分泌病 , and result in chronic superficial disfiguring 损坏 infections of any or all areas of skin or mucosa.

3. immunity:

Cell-mediated immune responses, especially CD4 cells, are important in controlling mucocutaneous 粘膜与皮肤 candidiasis, and the neutrophil 嗜中性粒细胞 is probably crucial 至关紧要的for resistance to systemic candidiasis.

4. Diagnosis: SputumScrapings from lesionsBlood smearsVaginal dischargeUrineFeces标本 : 拭子和表皮病损刮取物、血液、脊髓液、组织活检、尿液和渗出物等

5. Prevention and Treatment:

Amphotericin B

Nystatin 制霉菌素Ketoconazole苯并二氢呋喃酮 Fluconazole 氟康唑

B. Other opportunistic mycoses ( 自学 )

1. Aspergillus 曲霉

2. Mucor 毛霉

3. Pneumocystis carinii 卡氏肺孢菌

总 结

致病性真菌可引起哪些类型的疾病？引起系统性真菌病主要有什么菌？新型隐球菌的染色特点？培养特点？新型隐球菌引起的疾病？白色念珠菌的结构特点？白色念珠菌引起的疾病？