New aspects of the role of MR/P fimbriae in Proteus mirabilis urinary tract infection

Proteus mirabilis, a common cause of urinary tract infection (UTI), produce s a number of different fimbriae including mannose-resistant Proteus-like f imbriae (MR/P). The precise role of different P. mirabilis fimbriae in asce nding UTI has not yet been elucidated. In this study, a clinical isolate of P. mirabilis and an isogenic mutant unable to express MR/P were tested usi ng different experimental approaches. They were tested for their ability to cause infection in an ascending co-infection model of UTI and in a haemato genous model in the mouse. In both models, the mutant was less able than th e wild-type strain to colonise the lower and upper urinary tracts although infectivity was not abolished. In vitro adherence to uroepithelial cells wa s also assessed. Significant differences in adherence between both strains were observed at 1 h but not at 15 min post infection. We have also shown t hat a wild-type strain carries two copies of the mrpA gene. These data rein force the importance of MR/P fimbriae in P. mirabilis UTI although other vi rulence factors may be necessary for efficient colonisation and development of infection. (C) 2001 Federation of European Microbiological Societies. P ublished by Elsevier Science B.V. All rights reserved.