Proteus mirabilis, a Gram-negative rod-shaped bacterium most noted for its swarming motility and
urease activity, frequently causes
catheter-associated
urinary tract infections (CAUTIs) that are often polymicrobial. These
infections may be accompanied by
urolithiasis, the development of bladder or
kidney stones due to alkalinization of urine from
urease-catalyzed
urea hydrolysis. Adherence of the bacterium to epithelial and
catheter surfaces is mediated by 17 different fimbriae, most notably MR/P fimbriae. Repressors of motility are often encoded by these fimbrial operons. Motility is mediated by flagella encoded on a single contiguous 54-kb chromosomal sequence. On
agar plates, P. mirabilis undergoes a morphological conversion to a filamentous swarmer cell expressing hundreds of flagella. When swarms from different strains meet, a line of demarcation, a "Dienes line," develops due to the killing action of each strain's
type VI secretion system. During
infection, histological damage is caused by
cytotoxins including
hemolysin and a variety of
proteases, some autotransported. The pathogenesis of
infection, including assessment of individual genes or global screens for virulence or fitness factors has been assessed in murine models of ascending
urinary tract infections or CAUTIs using both single-species and polymicrobial models. Global gene expression studies performed in culture and in the murine model have revealed the unique metabolism of this bacterium.
Vaccines, using MR/P fimbria and its adhesin, MrpH, have been shown to be efficacious in the murine model. A comprehensive review of factors associated with
urinary tract infection is presented, encompassing both historical perspectives and current advances.