Proteus mirabilis fimbriae: identification, isolation, and characterization of a new ambient-temperature fimbria.

Urinary tract infections involving Proteus mirabilis may lead to complications including bladder and kidney stones, acute pyelonephritis, and bacteremia. This bacterium produces a number of fimbriae, two of which, MR/P fimbria and P. mirabilis fimbria, have been shown to contribute to the ability of this pathogen to colonize the bladder and kidney. We have now purified and characterized a previously undescribed fimbria of P. mirabilis, named ambient-temperature fimbria (ATF). Electron microscopy of a pure preparation and immunogold labeling of cells demonstrated that ATF was fimbrial in nature. The major fimbrial subunit of ATF has an apparent molecular weight of 24,000. The N-terminal amino acid sequence, E-X-T-G-T-P-A-P-T-E-V-T-V-D-G-G-T-I-D-F, did not show significant similarity to that of any previously described fimbrial protein. ATF was expressed by all eight P. mirabilis strains examined. Culture conditions affected expression of ATF, with optimal expression observed in static broth cultures at 23 degrees C. This fimbria was not produced by cells grown at 42 degrees C or on solid medium. Expression of ATF did not correlate with mannose-resistant/Proteus-like (MR/P) or mannose-resistant/Klebsiella-like (MR/K) hemagglutination and represents a novel fimbria of P. mirabilis.