This collection features four peer-reviewed literature reviews on bacterial diseases affecting pigs. The first chapter summarises recent research on the causes and epidemiology of major bacteria, viruses and parasites found in pig production, focussing on those with a particular impact on safety and global production, such as Escherichia coli (E. coli), Salmonella typhimurium and African swine fever virus. The second chapter discusses classical phenotypic characteristics and more advanced molecular techniques to identify and classify bacterial pathogens affecting swine health and performance. The chapter explores the different modes of transmission, as well as the commonly used measures for prevention and control, including vaccinations. The third chapter reviews the development of dysbiosis and post-weaning diarrhoea (PWD) in piglets and the consequent economic losses these diseases cause for the global pig industry. The chapter considers the role of animal nutrition and dietary strategies to optimise gut function as a means of preventing dysbiosis and PWD. The final chapter assesses methods of improving gut function in pigs to optimise health and prevent pathogen colonization. The chapter discusses research on genes associated with pathogen resistance and porcine immune response and reviews the role of dietary and nutritional strategies in preventing intestinal pathogen colonisation.