Although S. cholerasuis is contracted by ingestion of contaminated material, usually from an animal, it normally does not cause any enteric symptoms. Rather, it invades the epithelial mucosa and spreads to the bloodstream.
Secondary infections can occur at almost any site.
Infections with this species of Salmonella are, thus, much more serious than infections with S. enteriditis or S. typhimurium but not usually as serious as infections with S. typhi. Salmonellae are members of the family Enterobacteriaceae. The identification of the Enterobacteriaceae is complicated and involves a large number of tests. Of primary importance is the fermentation of lactose, which Escherichia and Klebsiellae can accomplish, but which Shigella, Salmonella, and Proteus cannot. Entero- bacteriaceae include indole, urease, hydrogen sulfide, and gas production.