title: Mannose-resistant Proteus-like fimbriae are produced by most Proteus mirabilis strains infecting the urinary tract, dictate the in vivo localization of bacteria, and contribute to biofilm formation.
abstract: Proteus mirabilis, an etiologic agent of complicated urinary tract infections, expresses mannose-resistant Proteus-like (MR/P) fimbriae whose expression is phase variable. Here we examine the role of these fimbriae in biofilm formation and colonization of the urinary tract. The majority of wild-type P. mirabilis cells in transurethrally infected mice produced MR/P fimbriae. Mutants that were phase-locked for either constitutive expression (MR/P ON) or the inability to express MR/P fimbriae (MR/P OFF) were phenotypically distinct and swarmed at different rates. The number of P. mirabilis cells adhering to bladder tissue did not appear to be affected by MR/P fimbriation. However, the pattern of adherence to the bladder surface was strikingly different. MR/P OFF colonized the lamina propria underlying exfoliated uroepithelium, while MR/P ON colonized the luminal surfaces of bladder umbrella cells and not the exfoliated regions. Wild-type P. mirabilis was usually found colonizing intact uroepithelium, but it occasionally adhered to exfoliated areas. MR/P ON formed significantly more biofilm than either P. mirabilis HI4320 (P = 0.03) or MR/P OFF (P = 0.05). MR/P OFF was able to form a biofilm similar to that of the wild type. MR/P ON formed a three-dimensional biofilm structure as early as 18 h after the initiation of the biofilm, while MR/P OFF and the wild type did not. After 7 days, however, P. mirabilis HI4320 formed a 65-mum-thick biofilm, while the thickest MR/P ON and MR/P OFF biofilms were only 12 mum thick. We concluded that MR/P fimbriae are expressed by most P. mirabilis cells infecting the urinary tract, dictate the localization of bacteria in the bladder, and contribute to biofilm formation.
authors.affiliation: Department of Microbiology and Immunology, University of Michigan Medical School, 1150 West Medical Center Drive, Ann Arbor, MI 48109-0620, USA.
authors.forename: Angela M
authors.initials: AM
authors.lastname: Jansen
authors.forename: Virginia
authors.initials: V
authors.lastname: Lockatell
authors.forename: David E
authors.initials: DE
authors.lastname: Johnson
authors.forename: Harry L T
authors.initials: HL
authors.lastname: Mobley
mesh_terms: D000818:Animals; D018441:Biofilms / Q000254:growth & development*; D005260:Female; D010861:Fimbriae, Bacterial / Q000187:drug effects / Q000502:physiology*; D008358:Mannose / Q000494:pharmacology*; D051379:Mice; D008808:Mice, Inbred CBA; D010641:Phenotype; D011513:Proteus mirabilis / Q000502:physiology*; D001743:Urinary Bladder / Q000382:microbiology; D014552:Urinary Tract Infections / Q000382:microbiology*
chemical_list: D008358:Mannose