Crépin, S

Dozois, CM

Harel, J

Houle, S

BMC Proceedings

English

PubMed

S Crépin

S Houle

J Harel

CM Dozois

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POSTER PRESENTATION Open Access
Decreased virulence of a uropathogenic
Escherichiacoli pst mutant is attributed to the
repression of Type 1 fimbriae
S Crépin1,2*, S Houle1, J Harel2,3, CM Dozois1,2,3
From Institut Pasteur International Network Annual Scientific Meeting
Hong Kong. 22-23 November 2010
Extra-intestinal pathogenic E. coli cause urinary tract
infections (UTIs), newborn meningitis, abdominal sepsis
and septicemia. UTIs affect millions of women annually,
and result in significant health care costs and morbidity
worldwide. Uropathogenic E. coli (UPEC) is the predo-
minant urinary tract pathogen, causing up to 85% of
UTIs. Despite appropriate therapy, recurrent episode of
UTI are common and bacterial strains are increasingly
more resistant to many currently used antimicrobial
agents. The pstSCAB-phoU operon encodes the phos-
phate specific transport system (Pst) and belongs to the
Pho regulon, which is regulated by the two-component
regulatory system (TCRS) PhoBR. Inactivation of the Pst
system in E. coli and other bacteria leads to constitutive
activation of the Pho regulon, perturbations in cellular
adaptation, and decreased virulence. The role of the Pst
system in uropathogenic E. coli (UPEC) was assessed by
deleting the pstSCA genes in UPEC strain CFT073. In
competitive (co-challenge) and single-strain infections,
the pst mutant was attenuated for colonization of both
the bladder and kidneys of CBA/J mice and was
impaired for production of Type 1 fimbriae. Type 1 fim-
briae are essential for UPEC virulence and their phase-
variable expression is positively and negatively regulated
by FimB and FimE, respectively. In vitro, in LB broth
and human urine, repression of the fim structural gene
fimA in the pst mutant correlated with increased orien-
tation of the fim promoter in the OFF-position. In vivo,
down-regulation of fimA in CFT073 Δpst correlated
with the up-regulation of fimE. To confirm the specific
role of repression of fim expression by the pst mutant
during UTI, fim phase locked-ON pst derivatives of the
pst mutant and WT CFT073 strains were constructed.
Compared to the pst mutant, the fim phase locked-ON
pst derivative demonstrated a significant gain in coloni-
zation of the bladder, that was similar to that of
CFT073 WT and CFT073 fim locked-ON strains. As
Type 1 fimbriae are important for UPEC virulence, by
promoting adhesion, our results suggest that the
reduced bladder colonization by the pst mutant during
UTI is predominantly attributed to down-regulation of
these fimbriae. Since the Pho regulon is controlled by
the TCRS PhoBR, molecules inducing the expression of
the Pho regulon through inactivation of Pst or activation
of PhoBR could potentially impair UPEC virulence by
inhibiting colonization and the infection cycle, which is
dependent on expression of type 1 fimbrial adhesins.
Author details
1INRS-Institut Armand-Frappier, 531 boul. des Prairies, Laval, Québec, Canada
H7V 1B7. 2Centre de Recherche en Infectiologie Porcine (CRIP), Université de
Montréal, Faculté de Médecine Vétérinaire, Saint-Hyacinthe, Québec, Canada
J2S 7C6. 3Groupe de Recherche sur les Maladies Infectieuses du Porc
(GREMIP), Université de Montréal, Faculté de Médecine Vétérinaire, Saint-
Hyacinthe, Québec, Canada J2S 7C6.
Published: 10 January 2011
doi:10.1186/1753-6561-5-S1-P93
Cite this article as: Crépin et al.: Decreased virulence of a
uropathogenic Escherichiacoli pst mutant is attributed to the repression
of Type 1 fimbriae. BMC Proceedings 2011 5(Suppl 1):P93.
* Correspondence: sebastien.crepin@iaf.inrs.ca
1INRS-Institut Armand-Frappier, 531 boul. des Prairies, Laval, Québec, Canada
H7V 1B7
Full list of author information is available at the end of the article
Crépin et al. BMC Proceedings 2011, 5(Suppl 1):P93
http://www.biomedcentral.com/1753-6561/5/S1/P93
© 2011 Crépin et al; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.


Decreased virulence of a uropathogenic Escherichiacoli pst mutant is attributed to the repression of Type 1 fimbriae

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Decreased virulence of a uropathogenic Escherichiacoli pst mutant is attributed to the repression of Type 1 fimbriae

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