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in BROCK BIOLOGY OF MICROORGANISMS School of Life

1 Intimate strangers: Microorganisms in and on us Lecture 17 Human-Microbe Interactions Chapter 21 in BROCK BIOLOGY OF MICROORGANISMS School of Life Science and Technology Shanghai Jiao Tong University

2 I.BENEFICIAL MICROBIAL INTERACTIONS WITH HUMANS 对人体有益的微生物 17.1 Overview of Human-Microbial Interactions Normal flora 正常微生物区系 Microorganisms that are usually found associated with healthy body tissue Intimate, beneficial and sometimes essential relationships 与人关系 : 紧密, 有益, 有时是必需的 Parasites 寄生物 Organisms that live on or in another host organism, imparting no benefits to the host Pathogens 病源物 Parasites that causes damages to the host 造成寄主伤害的寄生物

3 Virulence:The quantitative measure of pathogenicity 毒力 : 致病能力的数值化测定 Infection: any situation in which a microorganism is established and growing in a host, whether or not the host is harmed. 感染 Infection is not synonymous with disease. 感染不等同于疾病

4 Host-Parasite Interactions (a) Loose association. (b) Adhesion. (c) Invasion into submucousal epithelial cells 侵入上皮细胞. Figure: Bacterial interactions with mucous membranes 微生物与粘膜的互作.

5 Normal flora of human host 人体正常菌群 Skin 皮肤 Oral cavity 口腔 Gastrointestinal tract 胃肠道 Respiratory tract 呼吸道 Urogenital tract 泌尿道

6 17.2 Normal flora of the skin 2 m 2 skin surface with periodic drying. The skin surface (epidermis) is not a favorable place for microbial growth. Sweat glands: most skin microorganisms are associated directly or indirectly with it. 多数皮肤微生物与汗腺有关 Eccrine glands 外分泌腺 Apocrine glands 顶分泌腺 Sebaceous glands 脂肪分泌腺 Underarm odor Develops as a result of bacterial activity in the apocrine secretions; 狐臭由顶分泌腺的微生物产生

表皮腺管真皮皮脂腺毛囊皮下组织 Figure: 21-02 The human skin.

7 表皮腺管真皮皮脂腺毛囊皮下组织 Figure: The human skin. Microorganisms are associated primarily with the sweat ducts and the hair follicles.

8 Normal flora of the skin Transient flora 临时菌群 The skin is continually being inoculated with transient microorganisms, which are unable to multiply and usually die. Resident flora 聚居菌群 Able to multiply, not merely survive. Gram-positive bacteria (primary constituents) Staphylococcus 葡萄球菌 Corynebacterium 棒杆菌 Propionibacterium acnes 痤疮丙酸杆菌 acne Gram negative bacteria (minor constituents) Acinetobacter 不动杆菌

9 Factors that affect the nature and extent of the skin normal flora Weather: affect the skin temperature and moisture. Age: children have a more varied microflora Personal hygiene:

10 17.3 Normal flora of the oral cavity Oral cavity contains a complex and heterogeneous microbial habitat. 口腔微生物复杂而多样化 Saliva: Contains very few nutrients and a number of antibacterial substance 唾液 Lysozyme-cell wall weakening 溶菌酶 Lactoperoxidase-singlet oxygen formation 乳过氧化物酶

11 The tooth Mineral matrix of calcium phosphate 珐琅质牙本质牙龈缝牙髓质齿龈牙槽骨牙周膜骨髓 Fig 21.3

12 Dental plaque formation 牙斑 The bacterial conolization occurs as a result of attachment of single bacterial cells, followed by growth of microcolonies. 单个细菌定植, 并形成微菌落 1. Form a thin organic film by the attachment of acidic glycoproteins from the saliva 细菌与酸性糖蛋白结合形成一薄层膜 2. Colonization of Streptococcus onto the film to form a thick bacterial zone-the plaque 链球菌在有机物膜上形成菌膜 : 牙斑 3. Filamentous Fusobacterium, spirochetes Borrelia, G + rods and G - cocci follow in heavy plaque 丝状梭杆菌, 包柔氏螺旋体, G+ 杆菌,G- 球菌形成厚的牙斑

13 Dental plaque development brushed Distribution of dental plaqueon brushed (top) and unbrushed (bottom) teeth. The numbers give the total area of dental plaque. The red areas indicate plaque. unbrushed

14 Dental caries (tooth decay) 驻牙 The tooth crevices retain food particles (dogs are highly resistant to tooth decay because the shape of their teeth does not favor retention of food) Acid products from dental plaque decay the tooth: Lactic acid bacteria ferment sugar into lactic acid which causes decalcification of the enamel 牙斑的酸性产物腐蚀牙齿 : 乳酸菌发酵糖而产生乳酸, 乳酸导致珐琅质脱钙 Incorporation of fluoride into the mineral matrix makes enamel more resistant to decalcification 氟化物 : 增加对脱钙作用的抵抗力

15 17.4 Normal flora of the gastrointestinal tract 胃肠道正常菌群

16 肛门 Fig 21.8 human gastrointestinal tract showing the distribution of nonpathogenic microorganisms usually found in normal individuals 胃肠道中正常微生物分布食道十二指肠空肠回肠结肠

17 Stomach About ph2. The bacterial count is generally very low. 细菌数量很低 Helicobacter pylori can colonize the stomach wall, resulting in ulcers 幽门螺杆菌定殖于胃壁, 造成溃疡.

18 Small intestine Separated into the duodenum and the ileum, with the jejunum connecting them. 小肠由十二指肠空肠和回肠组成. Duodenum: fairly acidic and resembles the stomach in its lack of a microbial flora. 十二指肠酸性大, 与胃一样缺少微生物菌群 Lower ileum: Cell number is cells/gram 回肠后段微生物数量增加

19 Large intestine Cecum 盲肠 + colon 结肠 Colon: bacteria are present in large numbers, 400 species identified, cell number: cells/gram 结肠中有大量细菌, 可有 400 多个种 The facultative aerobes consume any oxygen present, making the environment strictly anaerobic and favorable for the growth of obligate anaerobes. 兼性好氧菌消耗所有氧, 环境变为严格厌氧, 严格厌氧菌大量生长

20 Functions of the intestinal flora Steroid metabolism Vitamin synthesis Gas production Odor production Organic acid production Glycosidase reactions Table 21.2

17.5 Normal flora of other body regions 17.5.1 Normal flora of The respiratory tract The upper respiratory tract is the populated lower

21 17.5 Normal flora of other body regions Normal flora of The respiratory tract The upper respiratory tract is the populated lower respiratory with a large tract variety and relatively number of few microorganisms, microbial inhabitants, unless there is an ongoing active infection

22 Most common resident organisms: staphylococci, streptococci, diphtheroid bacilli, and G- cocci. 葡萄球菌, 链球菌, 类白喉杆菌,G- 球菌. Potentially harmful bacteria, such as staphylococcus aureus and streptococcus pneumoniae, are often part of the normal flora of the nasopharynx of healthy individuals. 条件致病菌如金黄色葡萄球菌和肺炎链球菌在健康人群的鼻咽部正常存在.

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投影片 1 單元一宿 1-1 人體正常微叢 1-2 健康成人身體上正常菌叢 1-2-1 皮膚 1-2-2 呼吸道 1-2-3 口腔 1-2-4 胃 1-2-5 腸道 1-2-6 殖泌尿道 1-3 伺機性微 (Opportunistic Microorganisms) 1-4 益菌 (Probiotics) 於人體應用報章延伸閱讀宿