Escherichia coli and the enterics

The rod-shaped facultative anaerobic Escherichia coli g-Proteobacteria has become the model organism for microbiology and the standard vector for molecular biology.  It is essential in human food digestion as it is the main producer of vitamin K from undigested food in the big intestine. Despite these obvious advantages it is also the most general cause of urinary tract infections and can also cause pneumonia or even meningitis. In the mind of the general public it is closely linked with outbreaks of diarrhea normally caused through the strain O157:H7 enteropathogenic E. coli. Most mammals have Escherichia species in their digestive systems but they are rarely dominant.

The genus Escherichia has a single species and is grouped with other medically important bacteria known as the enterics. This is a phylogenetically distinct set Enterobacteri- aceae) that includes Salmonella, Proteus, Shigella and Enterobacter. The significance of these organisms in disease in Table 2 has become a barrier in rationalizing their taxonomy. Escherichia and Salmonella share over 50percent genomic Shigella and identity over 70percent this would normally place them all as species in the similar genus.