三、感染过程中病原体的作用病原体的致病能力侵袭力invasiveness毒力virulence数量quantity of pathogens变异性variability16
侵袭力 invasiveness 毒力 virulence 数量 quantity of pathogens 变异性 variability 16
1.侵袭力直接侵入人体invadedirectlyLeptospira,filariformlarvaofAncylostoma先黏附于肠或支气管黏膜表面，再侵入组织细胞，如志贺菌、结核分枝杆菌。致泻性大肠埃希菌能表达受体（定植因子）和小肠细胞结合adhere,colonizeand produceenterotoxin:Vibriocholera通过细菌表面成分（如伤寒沙门菌V抗原）抑制吞噬而促进病原体扩散promotespread:ViantigenofSalmonellatyphi17
1.侵袭力 直接侵入人体 invade directly Leptospira, filariform larva of Ancylostoma 先黏附于肠或支气管黏膜表面，再侵入组织细 胞，如志贺菌、结核分枝杆菌。致泻性大肠埃 希菌能表达受体（定植因子）和小肠细胞结合 adhere, colonize and produce enterotoxin: Vibrio cholera 通过细菌表面成分（如伤寒沙门菌Vi抗原）抑 制吞噬而促进病原体扩散 promote spread：Vi antigen of Salmonella typhi 17
2.毒力毒素toxins一外毒素exotoxin(Vibriocholera,Clostridiumtetani，Corynebacteriumdiphtheriae)一内毒素 endotoxin (S.typhi, Sh.dysentery)其他毒力因子一穿透能力filariformlarvaofAncylostoma一侵能力Sh.dysenteriae一溶组织能力Entamoebahistolytica18
2.毒力 毒素 toxins — 外毒素 exotoxin (Vibrio cholera, Clostridium tetani, Corynebacterium diphtheriae) — 内毒素 endotoxin (S. typhi, Sh. dysentery) 其他毒力因子 — 穿透能力 filariform larva of Ancylostoma — 侵袭能力 Sh. dysenteriae — 溶组织能力 Entamoeba histolytica 18
3.数量同一种传染病，入侵病原体的数量与致病能力成正比Thenumberofinvadingpathogenispositiverelation withthe pathogenicity inthe same infectious disease不同的传染病，能引起疾病的最低病原体数量可有较大差异The least number of the pathogentoinduce disease differgreatly in different diseases.For example, S.typhiis 10000 and Sh.dysenteriae is only1019
3.数量 同一种传染病，入侵病原体的数量与致病 能力成正比 The number of invading pathogen is positive relation with the pathogenicity in the same infectious disease 不同的传染病，能引起疾病的最低病原体 数量可有较大差异 The least number of the pathogen to induce disease differ greatly in different diseases. For example, S. typhi is 10000 and Sh. dysenteriae is only 10 19
4.变异性变异因素variation factors一环境environmental、药物drug、遗传hereditary变异类型various forms一致病力变异pathogenicityvariation一抗原性变异antigenicvariation一耐药性变异drug-resistantvariation20
4.变异性 变异因素 variation factors — 环境 environmental、药物 drug、遗传 hereditary 变异类型 various forms — 致病力变异 pathogenicity variation — 抗原性变异 antigenic variation — 耐药性变异 drug-resistant variation 20