Proteus mirabilis is a type of bacterium found in soil, water and the human urinary tract. It is known to cause urinary tract infection as well as kidney stones in humans.
Proteus mirabilis is a rod-shaped bacterium that can shift from a highly flagellated, elongated form to a short, vegetative rod form. For this reason, it is named after the character Proteus from "The Odyssey," a creature with the ability to change forms. It can cause kidney stones in humans by producing high levels of urease, which hydrolizes urea, causing pH levels to rise and ultimately causing higher ammonium phosphate and calcium phosphate levels in the urine.