In recent years we have accumulated a great deal of knowledge on the features associated with virulence of pathogenic E. coli. A large number of virulence genes have been identified and their products characterised. Great strides have been made in our understanding of the pathogenic mechanisms and the bacterium-host interaction. However, much remains elusive in our understanding of pathogenicity at a cellular and sub-cellular level. This is largely due to E. coli genome's plasticity: it generates great variability and facilitates the rapid emergence of new pathogenic variants. Elucidating the mechanisms underlying the evolution of these pathogens and their interactions with the host are key stages for disease prevention. This book reviews the most important recent findings of the studies on pathogenic E. coli providing a timely overview of the field. Topics covered include: epidemiology of the disease in humans and animals and the biological mechanisms that shaped the pathogenic types of E. coli; shiga toxins; subtilase cytotoxin; cell cycle modulating toxins; the heat stable and heat labile enterotoxins; haemolysins; structural, molecular and functional characteristics of A/E lesions; colonization factor antigens of ETEC; enteroaggregative adhesion; host cell invasion; and the development of vaccinal strategies to confront the burden of disease. Chapters are written from a molecular and cellular biology standpoint but also include discussions of the findings with a wider perspective including considerations on public health and the impact on animal productions. Essential reading for everyone working on these and related pathogens.