Chapter 11Chapter 11bacterial infection bacterial infectionInfection Infection 感染vvThe process of interplay between M. The process of interplay between M. and host.and host.vvM. Host defensesM. Host defensesvvDifferent results after infectionDifferent results after infectionPathogen:Pathogen:A microorganism capable A microorganism capable of causing disease.of causing disease.NonpathogenNonpathogen: :A A microorganism microorganism that that does not cause disease.does not cause disease.Opportunistic Opportunistic pathogenpathogen条件致病菌: : some some non-pathogens non-pathogens may may cause cause diseases diseases under under some some special special conditions.conditions.Section 1 Section 1normal microbial normal microbial flora and opportunistic flora and opportunistic B.B.1.Normal flora 1.Normal flora 正常菌群正常菌群vThe various B. and F. that are permanent residents of certain body sitesvvary in number and kind from one site to anothervthe locations are usually skin, oropharynx, colon, and vagina (mucous membranes) 肠道的正常菌群健康青年 粪便涂片健康壮年 粪便涂片健康 中年 粪便 涂片鼻咽腔葡萄球菌、甲，丙型链球菌肺炎球菌、奈氏菌、类杆菌等外耳道 葡萄球菌、类白喉杆菌 绿脓杆菌、非致病性分枝杆菌表皮葡萄球菌 口腔 甲，丙型链球菌 类白喉杆菌、肺炎球菌 奈氏菌、乳杆菌、梭杆菌 螺旋体、放线菌、白念珠菌肠道 大肠杆菌、产气杆菌、变形杆菌 绿脓杆菌、葡萄球菌、厌氧性细菌 真菌、乳杆菌，双歧杆菌等阴道大肠杆菌、乳杆菌白念珠菌、类白喉杆菌非致病性分枝等皮肤 葡萄球菌、绿脓杆菌、白念珠菌 丙酸杆菌、类白喉杆菌、 非致病性分枝杆菌人 体 内 正 常 菌 群 的 分 布眼结膜 白色葡萄球菌、干燥杆菌尿道 白色葡萄球菌、类白喉杆菌、 非致病性分枝杆菌Role of normal floraRole of normal floravvkeep health keep health vvCause diseaseCause disease2. beneficial effects of the normal 2. beneficial effects of the normal flora flora vvPriming of immune systemPriming of immune systemplay an important role in the play an important role in the development of immunologic development of immunologic competencecompetenceInduce cross-reaction with Induce cross-reaction with pathogenic organismspathogenic organismsvvexclusionary effect exclusionary effect 生物拮抗生物拮抗 - - colonization resistance colonization resistance vvProduction of essential nutrients -Production of essential nutrients - - produce several B vitamins and - produce several B vitamins and vitamin Kvitamin K3. opportunistic B. 3. opportunistic B. 条件致病菌条件致病菌vvMany species among the normal Many species among the normal flora are opportunists.flora are opportunists.vvMember of the normal flora may Member of the normal flora may themselves produce disease under themselves produce disease under certain circumstances.certain circumstances.three conditions correlated with three conditions correlated with opportunistic infectionopportunistic infectionvvImmune system compromiseImmune system compromisevvDysbacteriosisDysbacteriosis 菌群失调vvChange of inhabiting places Change of inhabiting places dysbacteriosisdysbacteriosisvvWhen the resident flora is When the resident flora is disturbed, some little significant M. disturbed, some little significant M. may colonize, proliferate and may colonize, proliferate and produce diseases.produce diseases.vvMainly result from long term and Mainly result from long term and large doses antibiotics takenlarge doses antibiotics takennosocomialnosocomial infections infections 医院获得性感染医院获得性感染definitiondefinitionvvAny infection acquired while in hospitalAny infection acquired while in hospitalsourcessourcesvvHospital personnelHospital personnelvvEnvironmentEnvironmentvvMedical devices Medical devices 医疗用具vvBlood and blood productsBlood and blood productsSection 2 Section 2 bacterial bacterial pathogenesis pathogenesisPathogenPathogen病原菌病原菌: :have the capacity to have the capacity to initiate diseasesinitiate diseasesvvPathogenicityPathogenicity致病性致病性: :the capacity of B. to initiate diseases the capacity of B. to initiate diseases致病性致病性毒力毒力侵入数量侵入数量侵入途径侵入途径侵袭力侵袭力毒素毒素荚膜荚膜、微荚膜微荚膜黏附素黏附素侵袭性物质侵袭性物质内毒素内毒素外毒素外毒素表面结构表面结构 鞭毛鞭毛 生物被膜生物被膜侵袭性酶侵袭性酶侵袭素侵袭素virulencevirulence毒力毒力: :A quantitative measure of A quantitative measure of pathogenicitypathogenicityLDLD50:50: the number needed to kill half the the number needed to kill half the hostshostsIDID50:50: the number needed to cause the number needed to cause infectioninfection In half the hostsIn half the hostsBacterial virulence factorsBacterial virulence factorsvvInvasiveness Invasiveness 侵袭力侵袭力vvToxins Toxins 毒素毒素vvQuantity Quantity 数量数量vvPathway of bacterial entrance Pathway of bacterial entrance 途径途径invasivenessinvasivenessvv定居、生长繁殖、扩散定居、生长繁殖、扩散A. Adherence factors A. Adherence factors 粘附因子粘附因子vvSurface molecules of B.Surface molecules of B. pilipili lipoteichoiclipoteichoic acid acidprotein Fprotein FB. Invasion of host cells and tissuesB. Invasion of host cells and tissuesvv Capsule: prevent the phagocyte from Capsule: prevent the phagocyte from adhering to the B.adhering to the B.vvEnzymesEnzymesvvBacterial Bacterial biofilmsbiofilms 生物膜生物膜vvIntegrinIntegrin 整合素整合素enzymesenzymesvvtissue-degrading enzymestissue-degrading enzymesvvIgA1 proteasesIgA1 proteasesBacterial Bacterial b