Vaginal bacterium triggers recurrent E. coli infection in the mouse bladder

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Adapted Media Release

Findings suggest possible new
treatment target to prevent recurrent urinary tract infection in women.

In mice, exposure of the
bladder to a common vaginal bacterium awakened dormant Escherichia coli and
triggered recurrent urinary tract infections (UTIs). Published in PLOS
Pathogens, these findings could help improve understanding of recurrent UTIs in
Millions of women around the
world experience recurrent bladder infections. Many recurrent UTIs are thought
to occur when dormant E. coli present in the lining of the bladder are
reactivated, causing a new infection. However, potential triggers of this
reactivation have remained unclear.
Nicole Gilbert , Valerie
O’Brien, and Amanda Lewis of Washington University School of Medicine, St.
Louis considered the idea that certain vaginal bacteria, which are mechanically
transferred to the urinary tract during sexual activity, may damage bladder
tissue and lead to reactivation of E. coli infection.
To test this hypothesis,
Lewis’s team raised mice with dormant E. coli reservoirs in their bladders and
exposed their urinary tracts to two vaginal bacteria species commonly found in
women. Lactobacillus crispatus, found in high proportions in the healthy
vagina, had no effects. However, Gardnerella vaginalis, which can cause
problems in the reproductive tract when it grows excessively, damaged the cells
lining the bladder and activated the dormant E. coli, which emerged to cause a
new infection.
Mice exposed to G. vaginalis,
which was eliminated rapidly from the bladder, were also more likely to
experience life-threatening consequences of the recurrent E. coli UTI,
including severe kidney damage and systemic infection. The effects of G.
vaginalis persisted after the bacterium was no longer present in the urinary
These results indicate the
first plausible trigger of recurrent UTIs from dormant E. coli in the bladder.
They could also help explain previously found links between vaginal bacteria
species, sexual activity, and risk of recurrent UTIs in women.
Recurrent UTIs are usually
treated with antibiotics to kill the E. coli. If occasional exposure to G.
vaginalis does, indeed, cause recurrent infection in some women, then it could
serve as a potential new target of treatments to prevent recurrent UTIs. In
light of the rise of multi-drug resistant E. coli, such a strategy could prove
especially appealing.
“One of the important
findings of this study is that Gardnerella can cause damage to organs of the
urinary tract even in the absence of E. coli.,” explains Dr. Lewis.
“This has exciting implications, suggesting that Gardnerella exposures to
the bladder could be important for urologic diseases beyond recurrent UTI that
we don’t fully understand.”
Article: Transient microbiota
exposures activate dormant Escherichia coli infection in the bladder and drive
severe outcomes of recurrent disease, Gilbert NM, O’Brien VP, Lewis AL, PLOS
Pathogens, doi:10.1371/journal.ppat.1006238, published 30 March 2017.

Kayode Ojo
Kayode Emmanuel Ojo is the Co-Founder and Managing Director at SHEFFA Limited. He is presently studying Computer Science at the National Open University, Victoria Island, Lagos.