1/26/2016 How Bacterial Pathogens Damage Host Common strategies Cells of pathogenicity Learning Objectives If apathogen ove rcomes the Describe the function of siderophores. host defense.then the microbe can cause damage rend effeet o Using the host's nutrients 。 Causing direct damage at the site of infection Define the mechanisms of action of A-B Producing toxins that are toxins,membrane-disrupting toxins, transported to sites superantigens,and genotoxins. distant to the infection Describe the roles of plasmids and lysogeny in Inducing hypersensitivity pathogenicity. reactions Using the Host's Nutrients: Structure of enterobactin,a Siderophores type of bacterial siderophore =0 Iron is required for most pathogenic An example of iron transport across bacteria The membrane (CO-CH-CH2-0) Concentration of free iron in the body is low since most iron is bound to iron- transport proteins,such as lactoferrin, transferrin,and hemoglobin. Siderophores are proteins secreted by pathogens that bind iron more tightly than host cells. 1/26/2016 9 How Bacterial Pathogens Damage Host Cells Learning Objectives • Describe the function of siderophores. • Provide an example of direct damage, and compare this to toxin production. • Contrast the nature and effects of exotoxins and endotoxins. • Define the mechanisms of action of A-B toxins, membrane-disrupting toxins, superantigens, and genotoxins. • Describe the roles of plasmids and lysogeny in pathogenicity. Common strategies of pathogenicity If a pathogen overcomes the host defense, then the microbe can cause damage • Using the host’s nutrients • Causing direct damage at the site of infection • Producing toxins that are transported to sites distant to the infection • Inducing hypersensitivity reactions Using the Host's Nutrients: Siderophores • Iron is required for most pathogenic bacteria • Concentration of free iron in the body is low since most iron is bound to iron￾transport proteins, such as lactoferrin, transferrin, and hemoglobin. • Siderophores are proteins secreted by pathogens that bind iron more tightly than host cells. Structure of enterobactin, a type of bacterial siderophore. An example of iron transport across the membrane. - Complex is transported - Only just the iron is transported