The enteric bacteria areoxidase-negative, catalase-posHive (some exceptions), non-spore-forming, fermentative (often with gas), and usually motile. They are worldwide In distribution, and there are many nonpathogenicspecies and a relatively small number of potentially pathogenic species. Many enterobacteria are part of the normal flora of the Intestinal tract. Fecal contamination of water is indicated by the presenceof Escherichla coil, whose habitat is the intestine. Kith* (including Klebslella pneurnonlaa Enterobacter, and Cltrobacter species have been recovered from vegetables and wood products of the kind usedfor stable bedding.
The mode of infection is almost always by ingestion. Fomites are especially important. Some infections are endogenous. Urinary tract infections are an exception.
Some strains ofE. coil cause important diseases of domestic animals. Salmonellae, shigellae, and Yoshila path (the cause of plague) are frankly pathogenic. Some species of such genera as Proteus, SerranapKlebsklla, and Enterobacter are mostly opportunists that produce disease under certain circumstances, such as impaired immunity, trauma to tissues, debilitation, wounds, malnutrition, and exposure to heavydoses of bacteria (bovine mastitis).
The term EPEC is used rather loosely in veterinary medicine to refer to E. coli strains that cause intestinal...