细菌的感染与免疫.ppt

Chapter 7 Bacterial Infection and immunity Basic terms Bacterial infection（细菌的感染） Pathogen（病原菌） Nonpathogen （非病原菌） Opportunistic pathogen（机会致病菌） 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. Pathogen（病原菌） Pathogenic bacterium （致病菌） The 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. Opportunistic pathogen（机会致病菌） Conditioned pathogen（条件致病菌） Some bacteria are capable of causing diseases only 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 infectious disorder (e.g. AIDS). Outline Normal flora and opportunistic pathogen Bacterial pathogenesis The host immune defence system The initiation and course of infection Hospital infection Section 1 Normal flora and opportunistic pathogen ★ Normal flora（正常菌群） Normal 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 human’s health. Locations Surface tissues of skin Oral cavity Respiratory tract Gastrointestinal tract Genitourinary tract ★ Beneficial effects of the normal flora Biological 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） Anti-tumor （抗肿瘤作用） Biological antagonism (生物拮抗) Biological barriers（生物屏障） Receptor competition（受体竞争） Harmful metabolites（有害代谢产物） Nutrient competition（营养竞争） 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