Proteus mirabilis is part of the normal flora of the human gastrointestinal tract, and has been found in mice with immune dysfunction, where it has been shown to cause sepsis. It can also be found free-living in water and soil. However, when this organism enters the body through the urinary tract, wounds, or the lungs it can become pathogenic. Proteus mirabilis commonly causes urinary tract infections and the formation of stones.
Urinary tract infections caused by P. mirabilis occur usually in patients under long-term catheterization. The bacteria have been found to move and create encrustations on the urinary catheters. Proteus mirabilis can enter the bloodstream through wounds. This happens with contact between the wound and an infected surface. The bacteria induce an inflammatory response that can cause sepsis and systemic inflammatory response syndrome (SIRS). P. mirabilis can also, though less common, colonize the lungs. This is the result of infected hospital breathing equipment and causes pneumonia.
Animal models of inflammatory bowel disease
According to a paper entitled, Biodiversity and Functional Genomics in the Human Microbiome, fostering or co-caging healthy mice with IBD-predisposed mice is sufficient to cause IBD in the healthy mice; which correlates with the transfer of Proteus mirabilis from the IBD mice to the healthy mice [PubMed].
Symptoms of urethritis are mild and can be easily treated. In some cases, Pyelonephritis (kidney infection) can occur when the bacteria migrate from the lower urinary tract. These cases are considered more serious. Common symptoms include:
Frequency of urination
Pyuria (presence of white blob cells in the urine)
Cystitis (bladder infection)
Hematuria (presence of red blood cells in the urine)