This introductory textbook explores bacterial disease mechanisms and bacteria-host interactions. The central premise is that bacteria have evolved by means of manipulating normal host cell functions and overcoming host defense systems to ensure their survival. As well as offering a new perspective on the classical bacterial virulence mechanisms, this book outlines the new molecular techniques developed to unravel the complexity of bacteria-host interactions. Current research may lead not only to a better understanding of disease mechanisms, but also to new means of preventing and/or treating bacterial infections.