The growing body of information on bacteria pathogenic for humans, mammals and plants generated within the past ten years has shown the interesting conservation of newly identified genes that playa direct role in the pathogenic mechanism. In addition to these genes, there are also genes that confer host specificities and other traits important in pathogenesis on these pathogens. In this volume, we have organized the subject areas to best fit the concept on the way bacterial pathogens recognize, interact and invade the host, on the regulation of genes involved in virulence, on the genes...