Proteus comes under the family <em>Enterobacteriaceae </em>and is often associated with urinary tract infections in animals and humans. These bacteria are often the part of intestine but become pathogenic when enter into urinary tract.
<em>Proteus mirabilis</em> is a gram negative anaerobic bacteria present as normal flora of intestine known to cause urinary tract infections in humans but most of the urinary tract infection is caused by <em>E. coli.</em><em> </em>
When these bacteria get into the blood stream they can cause systemic inflammatory response syndrome and sepsis which has very high mortality rate.
The primary difficulty is the fact that we do not know all of the organisms that currently exist in the world along with those that existed in the past.