Health & Environmental Research Online (HERO)


Print Feedback Export to File
3106419 
Journal Article 
Construction of a flagellum-negative mutant of Proteus mirabilis: Effect on internalization by human renal epithelial cells and virulence in a mouse model of ascending urinary tract infection 
Mobley, HLT; Belas, R; Lockatell, V; Chippendale, G; Trifillis, AL; Johnson, DE; Warren, JW 
1996 
Yes 
Infection and Immunity
ISSN: 0019-9567
EISSN: 1098-5522 
64 
12 
5332-5340 
WOS:A1996VU63500064 
To examine the role of flagella in pathogenesis of urinary tract infection caused by Proteus mirabilis, we constructed a nonmotile, nonswarming flagellum mutant of strain WPM111 (an hpmA hemolysin mutant of strain BA6163, chosen because of its lack of in vitro cytotoxicity in renal epithelial cell internalization studies). A nonpolar mutation was introduced into the flaD gene, which encodes the flagellar cap protein. This mutation does not affect the synthesis of flagellin but rather prevents the assembly of an intact flagellar filament. In in vitro assays, the genetically characterized nonmotile mutant was found to be internalized by cultured human renal proximal tubular epithelial cells in numbers less than 1% of those of the flagellated parent strain. Internalization of the nonmotile mutant was increased significantly (14- to 21-fold) by centrifugation onto the monolayer. To assess virulence in vivo, CBA mice were challenged transurethrally with 10(7) CFU of P. mirabilis BA6163 (wild type) (n = 16), WPM111 (hpmA mutant) (n = 46), or BB2401 (hmpA FlaD mutant) (n = 46). Differences in quantitative cultures between the parent strain and the hemolysin-negative mutant were not significant. However, the hpmA flaD mutant was recovered in numbers approximately 100-fold lower than those of the hmpA mutant or the wild-type parent strain and thus was clearly attenuated. We conclude that while hemolysin does not significantly influence virulence, flagella contribute significantly to the ability of P. mirabilis to colonize the urinary tract and cause acute pyelonephritis in an experimental model of ascending urinary tract infection.