RECURRENT urinary tract infections (UTIs) in women have been suggested to be triggered when the bladder is exposed to common vaginal bacterium, activating dormant Escherichia coli. UTIs are a common infection that affect millions of women around the world, yet it is unknown what triggers the reactivation.
Researchers have proposed that bladder tissue may be damaged by certain vaginal bacteria that are transferred through sexual activity to the urinary tract. This damage may lead to the reactivation of dormant E. coli and the individual to become infected once more.
To investigate this theory, mice with dormant E. coli in their bladders were raised by the team of researchers. Their urinary tracts were then exposed to Gardnerella vaginalis and Lactobacillus crispatus, two common types of vaginal bacteria species found in women. With excessive growth, G. vaginalis causes problems in the reproductive tract. When mice were exposed to G. vaginalis, it activated dormant E. coli and damaged the lining of the cells in the bladder. In contrast, L. crispatus, found in high quantities in the healthy vaginas, was found to have no effect.
Furthermore, life-threatening consequences as a result of recurrent E. coli, such as systemic infections and kidney failure, were more likely to affect the mice that were administered G. vaginalis. Even after G. vaginalis was no longer present in the urinary tract, the effects of the bacterium were still evident. These results can not only help to explain the links between sexual activity, vaginal bacteria species, and the recurrence of UTIs in women, but they also offer the first credible trigger for UTIs recurring from inactive E. coli found in the bladder.
One of the lead study authors, Dr Amanda Lewis, Washington University School of Medicine, St Louis, Missouri, USA explained: “One of the important findings of this study is that G. vaginalis can cause damage to organs of the urinary tract even in the absence of E. coli.” She continued: “This has exciting implications, suggesting that G. vaginalis exposures to the bladder could be important for urologic diseases beyond recurrent UTI that we do not fully understand.”