It has long been believed that urine was sterile. However, new techniques of urine culture and DNA sequencing have revealed a thriving community of bacteria and probable viruses, fungi and yeasts in the human bladder, known as the urobiome. Cutting-edge research is endeavouring to elucidate the role of these communities within the bladder and how they are responsible for your bladder’s health. If you’ve ever suffered from UTIs or are interested in preventing them, Miss Rhiannon Bray, Consultant Gynaecologist at New Victoria Hospital, tells you about the latest research on bladder infections and why bladder bacteria matter.


It is estimated that about 50% of women will suffer from UTIs in their life, whereas men are much less likely to be affected by them. Women are more prone to infections due to their urinary system anatomy. 
Urinary tract infections can be caused by gastrointestinal bacteria that travel to the urinary system, not emptying your bladder properly, sexual intercourse and wiping incorrectly can trigger conditions.
However, these are not the only factors to consider when it comes to identifying the root of your infections. The urobiome might be responsible for your symptoms.
Although more research is needed, some urobiome factors that are responsible for your bladder health are:

  • Your urobiome composition
  • Lactobacilli strains presence
  • Bacteria diversity

Good bacteria and bad bacteria

Just as the Human Microbiome Project has revealed the bacterial communities of the gut and their importance in human health, good and bad bacteria are vital in bladder’s health as well.
Escherichia coli (E. coli) bacteria was originally identified as one of the first bacterial culprits to cause urinary tract infection (UTI), and has been implicated in up to 88% of UTIs. However, despite courses of antibiotics we sometimes struggle to eradicate patients' infections.

We now understand from studies using electron microscopes that E.coli has the ability to travel inside the cells of the bladder lining and can hide in structures called ‘bio-pods’. These pods can render bacteria resistant to host defences, antibiotics and be a cause of recurrent urinary tract infections.   

Are bad bacteria the only UTI culprits?

Using these new technologies, teams have examined the bacteria found inside the cells of the bladder lining. Interestingly, those bacteria that we usually link to urinary tract infections have been found in both patients with and without UTIs.  

This opens the door to the idea that infections may not be linked to one particular harmful bacteria, and the whole bacterial population may be relevant.  

Lactobacillus and incontinence

The underlying causes of urinary incontinence are not well understood.  

One of the first studies designed to compare women with and without symptoms, compared the bacteria found in the urine of women with and without urgency urinary incontinence (UUI).  
Patients with incontinence were found to have less of a type of bacteria called Lactobacillus.  
This particular strain of bacteria has already been publicised as a Pro-biotic or a good bacteria.  

We know it has the ability to produce chemicals that can inhibit the growth of other bacteria. It may also have capabilities that allow it to regulate the human immune system. It even has potential as a new treatment. In human studies administration of particular strains of lactobacilli led to a reduction in recurrent urinary tract infections and urgency and frequency.  
Interestingly in postmenopausal women with bladder symptoms, replacing vaginal oestrogen, which is lacking after menopause, has been linked to an increase in Lactobacillus in the urine of these women.  Already a greater understanding of the bacterial community is enabling us to design and trial new treatments.  

The right bacteria diversity is key to bladder health.

Diversity is a term used to describe the number of different strains of bacteria within a sample. Another study examined the diversity of the urobiome. Similar work has already been undertaken on the gut microbiome, and we are encouraged to eat a wide variety of fruit and vegetables to increase the variety and numbers of different bacteria in our gut.  

When looking at the diversity of the urobiome, there has been conflicting results.  Some groups have linked an increased diversity of bacteria with urinary symptoms, whereas other have linked decreased diversity with urinary symptoms such as OAB.  

Both arguments are plausible. 

Extremes of diversity are unlikely to be beneficial.  A minimal diversity might mean that there is an absence of beneficial microbes, and a maximal diversity could mean a lack of the important inhibitory mechanisms that control and regulate numbers of bacteria in the bladder. 

Bacteria diversity and treatment outcome

Differences in the urobiome have been linked to the chance of responding to medication.  

Urgency incontinence is often preceded by Overactive Bladder (OAB) symptoms such as increased urinary frequency and urgency. It can be treated with medication to relax the bladder. 

Some groups have examined the urobiome of patients who do and don’t respond to one of these bladder treatments.  
Patients who responded well to the medication had fewer bacteria and a less diverse bacterial community at baseline. This was similar to the diversity found in the patients without symptoms.
The patients who did not respond to the medication had a more diverse community, and bacterial species typically not found in those patients who responded well to the medication. Bacterial diversity in the women who required a higher dose of the medication to achieve adequate symptom control was also more similar to the diversity found in non-responders, therefore bacterial diversity has been proposed as a tool to predict which patients best respond to particular treatments.  It also raises the possibility that altering the urobiome might mean that treatments are more likely to work.   

The optimal characteristics of the urobiome are not yet known, but we believe some bacteria may play a protective role in the bladder as they do in other biological niches.

There are many questions still to be answered. 
Does the incontinent bladder select for some bacteria over others? Do these bacteria contribute to symptoms? Does the presence of incontinence alter the microbial community? Does diet affect the urobiome?  

Undoubtedly, this is a very exciting time for bladder health.  

For many years, there has been a lack of successful or new treatments and patients have been suffering in silence.  We are now entering a new era of molecular information that will help us to better understand bladder conditions.  With this new information will come the opportunity to revolutionise future treatments and bladder health.   


If you are a woman suffering  from UTIs,  you can book an appointment with our Urogynaecology Consultants  or urologists by calling us on 020 8949 9020 or:

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