Preface

Salmonella is a gram-negative microorganism, widely dispersed in nature and often found in the intestinal tract of animals and humans. More than 2,500 serotypes of Salmonella exist, but only some of these serotypes have been frequently associated with food-borne illnesses. The pathogenic *Salmonella* is a life-threatening bacterium, and it is a leading cause of food-borne bacterial illnesses in humans. After Campylobacter, Salmonella is the second most predominant bacterial cause of foodborne gastroenteritis worldwide. Salmonella pathogens may primarily spread through the feces of wildlife and domestic animals, contaminated water, poor fertilization methods, and other agricultural practices. Salmonella serotypes can grow and survive in many different foods. The behavior of Salmonella in foods is governed by a variety of environmental and ecological factors. These include water activity, pH, chemical composition, the presence of natural or added antimicrobial agents, and storage temperature and processing factors, such as the application of heat and physical manipulation.

Food-borne infections from Salmonella are obtained through ingesting contaminated food or water. Poultry, eggs, beef, and milk products are the main vehicles in the salmonellosis outbreak, and secondary sources are foods, such as fruits, vegetables, and seafood. Since 1962, registered cases of human salmonellosis caused by contaminated food have been steadily increasing. Salmonellosis, or Salmonella infection, caused by nontyphoid strains is the most common food-borne disease reported from population-based, active laboratory surveillance in the United States. However, since the 1980s, food-borne salmonellosis from Salmonella serotypes Typhimurium and Enteritidis has increased. The Centers for Disease Control and Prevention (CDC) revealed that the incidence of Salmonella infections in 2010 was significantly higher than during the period 2006–2008.

Often, most people who suffer from Salmonella infections may have temporary gastroenteritis, which usually does not require treatment. However, when infection becomes invasive, antimicrobial treatment is mandatory. Symptoms generally occur 8 to 72 hours after ingestion of the pathogen and can last 3 to 5 days. Children, the elderly, and immunocompromised individuals are the most susceptible to salmonellosis infections. The annual economic cost due to food-borne Salmonella infections in the United States alone is estimated at \$2.4 billion, with an estimated 1.4

#### XII Preface

million cases of salmonellosis and more than 500 deaths annually. Many milder cases are not reported, making the estimated number of salmonellosis cases in the United States thirty times the number of reported cases.

The chapters contained in this book describe a range of different topics*,* such as the role of foods in Salmonella infections, food-borne outbreaks caused by Salmonella, biofilm formation by Salmonella (Salmonella grows predominantly as biofilm in most of its natural habitats). Additional topics include antimicrobial drug resistance of Salmonella isolates (the multidrug resistance of Salmonella, which reduces the therapeutic options in cases of invasive infections and could potentially be associated with an increased burden of illness), methods for controlling Salmonella in food, and Salmonella isolation and identification methods to ensure the safety of food. Contributing to this book are internationally renowned scientists who have provided a diverse and global perspective of the issues of concern with the Salmonella pathogen. This book serves as an excellent resource for those interested in Salmonella. In fact, this book is intended to be primarily a reference book. However, it also summarizes the current state of knowledge regarding Salmonella, and it contains ideas for future research. The editor is indebted to the participating authors for their state-of-the-art contributions in providing authoritative views resulting from their research on this dangerous Salmonella pathogen.
