They are defined as rod-shaped Gram-negative non-sporeforming organisms. Typical genera include: Citrobacter, Enterobacter Escherichia Hafnia Klebsiella Serratia Coliforms are abundant in the feces of warm-blooded animals,but can also be found in the aquatic environment, in soil and onvegetation. Typically, E. coli are about 11% of the coliforms in human feces.