Survival of uropathogenic Escherichia coli in the murine urinary tract is dependent on OmpR

Abstract

UropathogenicEscherichia coli(UPEC) can grow in environments with significantly elevated osmolarities, such as murine and human urinary tracts. OmpR is the response regulator part of a two-component OmpR–EnvZ regulatory system that responds to osmotic stresses. To determine the role of OmpR in UPEC survival, a ΔompRmutant was created in the UPEC clinical isolate NU149. The ΔompRmutant had a growth defect compared with the wild-type strain under osmotic stress conditions; this defect was complemented by the full-lengthompRgene on a plasmid, but not with a mutant OmpR with an alanine substitution for aspartic acid at the phosphorylation site at position 55. Furthermore, the ΔompRmutant displayed up to 2-log reduction in bacterial cell numbers in murine bladders and kidneys compared with wild-type bacteria after 5 days of infection. The ability of the bacteria to survive was restored to wild-type levels when the ΔompRmutant strain was complemented with wild-typeompR, but not when the alanine-substitutedompRgene was used. This study has fulfilled molecular Koch's postulates by showing the pivotal role OmpR plays in UPEC survival within the murine urinary tract.