Salmonellosis is an important public health problem in many countries and a frequent cause of gastroenteritis and zoonotic infections. Infections with Salmonellae that are resistant to multiple antimicrobials are associated with increased morbidity and mortality, and the global emergence of such organisms is leaving clinicians with few, or no, treatment options. The emergence and sustained circulation of multidrug (MDR) resistant Salmonellae have become problematic in many endemic regions. This book has tried to achieve baseline information about the molecular epidemiology of Salmonella enterica serovars in three middle Euphrates provinces in Iraq,through investigation of the phenotypic and genotypic diversity of Salmonella recovered from human, cattle and poultry . Particularly, drug resistance patterns, virulotypes and RAPD-genotypes of isolates from various sources were presented. In addition,the relationship between MDR Salmonella isolates, the carriage of some virulence genes and class I integron was evaluated.