IMPACTS OF FECAL BACTERIA ON HUMAN AND ANIMAL HEALTH— PATHOGENS AND VIRULENCE GENES

The presence of pathogens in our food and water supplies represents a significant risk to human and animal health. This chapter focuses on the most commonly occurring human pathogens of Enterobacteriaceae, such as Citrobacter, Enterobacter, Escherichia, Klebsiella, Proteus, Salmonella, Shigella, and Yersinia spp. Of these, special attention is given to pathogenic E. coli, which is the most diverse and studied member of Enterobacteriaceae. The types of disease caused by E. coli are grossly classified as either intestinal or extraintestinal. Six pathotypes of intestinal pathogenic E. coli are recognized, each with virulence factors making them distinct. Extraintestinal pathogenic E. coli, or ExPEC, is a broad group of pathogens that colonize the extraintestinal compartment of animal and human hosts, resulting in such diverse conditions as urinary tract infection, meningitis, peritonitis, and septicemia. Enterohemorrhagic E. coli (EHEC; sometimes referred to as Shiga toxin-producing E. coli, or STEC, or members thereof) are another diarrheal pathotype, well known for their ability to cause diarrhea, hemorrhagic colitis (HC), and hemolytic uremic syndrome (HUS). This chapter focuses on the pathogens and virulence genes of the Salmonella serovars implicated in foodborne gastroenteritis. It also focuses on the virulence genes of these pathogens with regard to genomic content. Already underway, the postgenomic era will lead to a better understanding of the importance of these genomic traits as they pertain to infection within humans.