General Information: Proteus mirabilis is a tetracycline resistant human urinary tract isolate. This bacterium is part of the normal gut flora of a healthy individual, but is also an opportunistic pathogen. Flagellar movement allows this organism to travel through the urinary tract into the bladder and kidney where it may cause infection or stones. Cell death is caused by hemolysin, a pore-forming toxin which disrupts osmotic balance across the host cell membrane. This species is inherently resistant to nitrofuran and tetracycline, and some strains have recently become resistant to ampicillin and trimethoprin.