Enterobacterial infections are caused by a group of bacteria that dwell in the intestinal tract of humans and other warm-blooded animals. The bacteria are all Gram-negative and rod-shaped. As a group they are termed Enterobacteriaceae. A prominent member of this group is Escherichia coli. Other members are the various species in the genera Salmonella, Shigella, Klebsiella, Enterobacter, Serratia, Proteus, and Yersinia.

The various enterobacteria cause intestinal maladies. As well, if they infect regions of the body other than their normal intestinal habitat, infections can arise. Often, the bacterial infection arises during the course of a hospital stay. Such infections are described as being nosocomial, or hospital acquired, infections. For example, both Klebsiella and Proteus are capable of establishing infections in the lung, ear, sinuses, and the urinary tract if they gain entry to these niches. As another example, both Enterobacter and Serratia can cause an infection...