双语细菌的感染与免疫

1、Basic termsBacterial infection（细菌的感染）Pathogen（病原菌）Nonpathogen （非病原菌）Opportunistic pathogen（机会致病菌）第一页，共六十八页。Bacterial Infection细菌的感染The process of bacteria invading in the body, growing in the tissues, producing toxins and causing diseases is called bacterial infection.第二页，共六十八页。Pathogen（病原菌）Pathogen

2、ic bacterium （致病菌）A bacterium which can cause a disease is called pathogen. Nonpathogen（非病原菌）Nonpathogenic bacterium（非致病菌）A bacterium that does not cause disease is called nonpathogen.第三页，共六十八页。Opportunistic pathogen（机会致病菌）Conditioned pathogen（条件致病菌）Some bacteria are capable of causing diseases only

3、 under certain conditions.These organisms can cause disease only if one or more of the usual defence mechanisms humans have evolved to restrict microorganisms from their usually sterile internal organs and tissue are breached by accident, by intent (e.g. surgery), or by an underlying metabolic or an

4、 infectious disorder (e.g. AIDS).第四页，共六十八页。OutlineNormal flora and opportunistic pathogenBacterial pathogenesisThe host immune defence systemThe initiation and course of infectionHospital infection第五页，共六十八页。Section 1 Normal flora and opportunistic pathogen正常菌群与机会致病菌第六页，共六十八页。 Normal flora（正常菌群）Norma

5、l microbial flora（正常微生物群）The population of microorganisms that inhabit the skin and mucous membranes of healthy persons. They are usually harmless, some even beneficial, to humans health.第七页，共六十八页。LocationsSurface tissues of skin Oral cavity Respiratory tractGastrointestinal tractGenitourinary tract

6、第八页，共六十八页。Normal flora on intestinal mucosa第九页，共六十八页。肠道的正常菌群第十页，共六十八页。第十一页，共六十八页。 Beneficial effects of the normal floraBiological antagonism （生物拮抗）Production of essential nutrients（营养作用）Priming of immune system（免疫作用）Anti-aging（抗衰老作用）第十二页，共六十八页。Biological antagonism (生物拮抗)Biological barriers（生物屏障）or

7、 Receptor competition（受体竞争)Harmful metabolites（有害代谢产物）Nutrient competition（营养竞争）第十三页，共六十八页。Conditioned pathogen（条件致病菌）Some bacteria are capable of causing diseases only under certain conditions. These bacteria are called opportunistic (conditioned) pathogens and this kind of infection is called oppo

8、rtunistic infection（机会性感染）. Opportunistic pathogen（机会致病菌）第十四页，共六十八页。 Conditions of opportunistic infectionChange of inhabiting places（寄居部位改变）Immune system compromise（宿主免疫功能低下）Dysbacteriosis（菌群失调）第十五页，共六十八页。Dysbacteriosis（菌群失调）If flora disequilibrium occurs, for example, when the resident flora is di

9、sturbed, some little significant microorganisms may colonize, proliferate, and produce disease, which is called dysbacteriosis. Dysbacteriosis mainly resulted from long term and large doses antibiotics taken.第十六页，共六十八页。Superinfection（重叠感染）A frequent complication of drug therapy for microbial infecti

10、on. It may result from opportunistic colonization following immunosuppression by the primary pathogen and can be influenced by the time interval between infections, microbial physiology, or host resistance. 第十七页，共六十八页。Dysbacteriosis and superinfection第十八页，共六十八页。肠道的正常菌群健康青壮年粪便涂片健康老年粪便涂片（双歧杆菌）第十九页，共六十

11、八页。Probiotics（益生菌）第二十页，共六十八页。Probiotics（益生菌）& Prebiotics（益生元）第二十一页，共六十八页。Section 2 Bacterial Pathogenesis细菌的致病作用Basic termsBacterial Pathogenicity Bacterial virulenceNumber of invading organismsPortal of entry 第二十二页，共六十八页。Pathogenicity（致病性） is used to describe the capacity of bacteria to initiate di

12、seases.The term of virulence（毒力） is used as a comparison of pathogenicity in the quantitative sense.ID50（median infectious dose, 半数感染量）: Infectious dose of bacteria for 50% of the test population.LD50 （median lethal dose, 半数致死量） : Lethal dose of bacteria for 50% of the test population.Basic Terms第二十

13、三页，共六十八页。ExotoxinPili (Fimbrial)CapsuleVirulent EnzymeAdhesinsFlagellaIron bindingproteinVirulence surface proteinBacterial virulence factors（细菌毒力因子）第二十四页，共六十八页。Bacterial virulence（细菌的毒力）Virulence（毒力）Invasiveness（侵袭力）Toxin（毒素）Adherence & permanent planting（黏附与定植）Multiplication &diffusion （增殖与扩散）Anti

14、-defense functionof host （免疫逃逸）Endotoxin（内毒素）Exotoxin（外毒素）第二十五页，共六十八页。Adhesion and field planting（黏附与定植）Invasion（侵入）Multiplication and diffusion（繁殖与扩散）Local diffusion（局部扩散）Systemic diffusion（全身性扩散）第二十六页，共六十八页。 Invasiveness（侵袭力）Definition: Bacterial capability that can break through the physiologic b

15、arriers (skin, mucosa), settle down, multiply, and spread in the host.Adhesive factors: adhesin and capsuleInvasive substancesBacterial biofilm第二十七页，共六十八页。1. Adhesin（黏附素）Protiens on bacterial surface associated with adhesion.Adhesins bind to adhesin receptors on host cells.Classification:Pilus (fimb

16、riae) adhesin (菌毛黏附素)Non-fimbriae adhesin (非菌毛黏附素)第二十八页，共六十八页。AdhesinAdhesinEpitheliumReceptorBacterium第二十九页，共六十八页。Capsule (荚膜) of streptococcus pneumoniaeMicrocapsule（微荚膜） Slime layer（黏液层）第三十页，共六十八页。Protect the cell wall against attack by drugs Inhibit ingestion and killing by phagocytesPlay a role

17、 in the adherence of human tissueAntigenicity2. Capsule（荚膜）第三十一页，共六十八页。3. Invasive enzymes侵袭性酶类 Some bacteria may generate invasive enzymes, which can damage body tissues and promote the invasion and diffusion of the bacteria.第三十二页，共六十八页。4. Invasin侵袭素Encoded by invasive genes（侵袭基因）Mediate invading a

18、djacent epithelial cells第三十三页，共六十八页。5. Bacterial biofilm细菌生物被膜： The membraneous bacterial community composed of bacteria and the extracellular polymers secreted by bacteria after they adhere to the surface of living or nonliving materials.第三十四页，共六十八页。5. Bacterial biofilm细菌生物被膜Facilitates bacterial a

19、dhesionBaffles the penetration of antibiotic and the rejection of immune systemProfits signal communication among bacteria.第三十五页，共六十八页。Bacterial biofilm第三十六页，共六十八页。第三十七页，共六十八页。 Biofilm in the endoscope（内窥镜）第三十八页，共六十八页。Staphylococcus epidermidis（表皮葡萄球菌）biofilm in the surface of venous catheter（静脉导管）第

20、三十九页，共六十八页。ExotoxinsEndotoxinsExcreted by living cells; high concentrations in liquid medium.Integral part of the cell wall of G- bacteria. Released on bacterial death and in part during growth. May not need to be released to have biologic activity.Produced by both G+ and G- bacteria.Found only in G

21、- bacteria.PolypeptidesLPS (lipid A portion probably responsible for toxicity.)Relatively unstable; toxicity often destroyed rapidly by heating at temperatures above 60.Relatively stable; withstand heating at temperatures above 60 for hours without loss of toxicity.第四十页，共六十八页。ExotoxinsEndotoxinsHigh

22、ly antigenic; stimulate formation of high-titer antitoxin (抗毒素). Antitoxin neutralizes toxin.Weakly immunogenic; antibodies are antitoxic and protective. Relationship between antibody titers and protection from disease is less clear than with exotoxins.Converted to antigenic, nontoxic toxoids (类毒素)

23、by formalin, acid, heat, etc. Toxoids are used to immunize.Not converted to toxoids.Highly toxic; fatal to animals in microgram quantities or less.Moderately toxic; fatal for animals in tens to hundreds of micrograms.第四十一页，共六十八页。ExotoxinsEndotoxinsUsually bind to specific receptors on cells.Specific

24、 receptors not found on cells.Usually do not produce fever in the host. Selective toxicity and specific clinical syndromes. Neurotoxins (神经毒素) Cytotoxins (细胞毒素) Enterotoxins (肠毒素)Usually produce fever in the host by release of IL-1 and other mediators.Frequently controlled by extrachromosomal genes

25、(e.g. plasmids).Synthesis directed by chromosomal genes.第四十二页，共六十八页。区别要点外毒素内毒素来源革兰阳性菌与部分革兰阴性菌革兰阴性菌编码基因质粒、前噬菌体或染色体基因染色体基因存在部分从活菌分泌出，少数菌崩解后释出细胞壁组分，菌裂解后释出化学成分蛋白质脂多糖稳定性6080，30分钟破坏160，24小时破坏毒性作用强，对组织器官有选择性毒害效应，引起特殊的临床表现较弱，各菌的毒性效应大致相同，引起发热、白细胞增多、微循环障碍、休克、DIC等抗原性强，刺激机体产生抗毒素；甲醛液处理脱毒形成类毒素弱，刺激机体产生的中和抗体作用弱；甲醛液

26、不能脱毒形成类毒素第四十三页，共六十八页。Specific polysaccharideLPS第四十四页，共六十八页。Procedure 第四十五页，共六十八页。Neurotoxin（神经毒素） Tetanus toxin（破伤风毒素）第四十六页，共六十八页。Cytotoxins（细胞毒素）Diphtheria toxin（白喉毒素）inhibits protein synthesis in mammalian cells and causes necrosis of cellsDiphtheria membrane on throat第四十七页，共六十八页。Enterotoxin（肠毒素）

27、Cholera enterotoxin 第四十八页，共六十八页。Biological roles of endotoxinFever（发热）Leukopenia and leukocytosis（白细胞反应 ）Endotoxemia and shock（内毒素血症与休克）第四十九页，共六十八页。EndotoxinActivatesmacrophagesActivatescomplementActivatesHageman factorIL-1 ,TNF, Nitric oxideFever and hypotensionC3a, C5a Hypotension EdemaCoagulation

28、 cascadeDIC第五十页，共六十八页。Section 4 the initiation and process of infectionSources of infectionPathway of bacterial entranceTypes of bacterial infection第五十一页，共六十八页。Exogenous infection（外源性感染）PatientsCarriers（带菌者）AnimalsEnodogenous infection（内源性感染）Opportunistic pathogens Sources of infection第五十二页，共六十八页。Pa

29、thway of pathogen entrance Respiratory Gastrointestinal Genital Skin and mucosa Animal bites Blood Sexual transmission第五十三页，共六十八页。Types of bacterial infectionInapparent infection（隐性感染）Apparent infection（显性感染）Carrier state（带菌状态）第五十四页，共六十八页。Inapparent infection（隐性感染）Subclinical infection（亚临床型感染）An inf

30、ection that has no observable symptoms.It occurs when the host immunity is potent or the pathogenicity of the pathogen is weak. 第五十五页，共六十八页。The tip of the iceberg 第五十六页，共六十八页。Apparent infection（显性感染）Acute infectionChronic infectionLocal infectionGeneralized infection Toxemia (毒血症)Endotoxemia (内毒素血症)

31、Bacteremia (菌血症)Septicemia (败血症)Pyemia (脓毒血症)第五十七页，共六十八页。Toxemia（毒血症）Bacteria mutiply at invading location and do not enter blood stream, but the exotoxins（外毒素）enter blood and cause corresponding toxic symptoms.Endotoxemia（内毒素血症）Gram-negative bacteria mutiply at location or in blood stream, release

32、a lot of amount endotoxin（内毒素） released from bacterial cell rupture.第五十八页，共六十八页。Bacteremia（菌血症）After entering blood, bacteria circulate but not multiply in the blood.Septicemia（败血症）Bacteria circulate and multiply in the blood, in which bacteria produce toxic products and cause high swinging type of

33、fever and other toxic symptoms.第五十九页，共六十八页。Pyemia（脓毒血症）Pyogenic（化脓性） bacteria produce septicemia with multiple abscesses（脓肿） in internal organs such as spleen , liver and kidneys.第六十页，共六十八页。 Carrier state（带菌状态）After inapparent infection or apparent infection, sometimes the pathogens are not eliminated in time, so the bacteria will survive and multiply in host at low speed, and bacteria spread into the environment.Carrier（带菌者） is important source of infection. 第六十一页，共六十八页。Hospital infectionDefinition Basic characteristicsClassificationMicrobial ecological characteristicsEpidemiological cha