What is a Urinary Tract Infection?

Causes, symptoms and prevention

Urinary tract infections (UTIs) are common infections that affect the bladder, the kidneys and the tubes that connect them(1). Both men and women can contract a UTI however, they are one of the most common bacterial infections seen in women(2,1). Women are more likely to contract a UTI compared to men for several reasons including:(3) 

  1. Women have a shorter urethra compared to men 
  2.  The urethra is closer to the anus in women
  3. The surrounding environment is more humid in women compared to men 

Having a UTI requires frequent trips to the toilet and results in painful or difficult urination, cloudy urine and occasionally haematuria (blood in the urine)(4). It can also leave people feeling uncomfortable and can impact their productivity and quality of life(1).

As mentioned before, UTIs occur when the urinary tract becomes infected, usually by bacteria. In most cases, bacteria from the gut enter the urinary tract through the urethra. There are also several other risk factors that may increase your risk of getting a UTI:(1).

  1. conditions that obstruct your urinary tract, such as kidney stones 
  2. difficulty emptying your bladder fully 
  3. using a contraceptive diaphragm or condoms coated in spermicide 
  4. diabetes
  5. a weak immune system 
  6. a urinary catheter (a tube in your bladder used to drain urine) 
  7. an enlarged prostate gland in men  

Nearly 1 in 3 women will experience at least one episode of UTI requiring antibiotic therapy between the age of 24 years and 25% of these women will experience a second UTI within 6 months(2). Recurrent UTIs are defined as more than 2 episodes in the last 6 months or 3 episodes in the last year. 5 Most of the recurrent UTIs seen in women occur in the presence of pathogenic E.coli in the urinary tract(6).

Antibiotics are commonly used to treat UTIs however, repeated treatment may result in antibiotic resistance and may adversely affect the balance of the gut microbiota. Therefore, antibiotic-free protective approaches are becoming more promising in recent years(7).

Can friendly bacteria be used to help treat my UTI? 

Bacteria in the urinary system have an important role in the health and balance of the urinary system and subsequently, there is a clear relationship between vaginal flora and urogenital infections. Most of the microorganisms present in the vagina are from the gastrointestinal tract. It has therefore been suggested that supplementing the gastrointestinal and vaginal flora with friendly bacteria may support and help prevent UTIs(7).

When examining the bacterial species present in the vaginal flora, microorganism species of Lactobacillus spp. are the most dominant bacteria. Lactobacillus spp. display antimicrobial properties which can reduce the risk of infection from pathogenic species.7 Since Lactobaccilus spp. are the most dominate species in the urinary tract, supplementing with friendly bacterial supplements containing Lactobacillus spp. can help restore the urinary microbiota and help prevent and treat UTIs. These bacteria are able to stop pathogenic bacteria like E.coli which can cause UTIs in the urinary tract, attaching to the urinary wall, stopping their growth and colonisation.(7).

Orally administered friendly bacteria reach the vagina via the anus and the perineal and vulvar skin, as do the pathogens that cause UTIs. The ability of friendly bacteria to reach the gut and the vagina has been shown by taking vaginal mucosa swaps and faecal samples after administration of the friendly bacteria(8).

What about cranberries? 

If you have ever experience a UTI I am sure someone has recommended cranberry juice to you. But can drinking a litre of cranberry a day really help treat your UTI?

Cranberries contain proanthocyanidins (PACs), the active ingredient in cranberries. PACs are able to inhibit the adherence of E.coli to the wall of the urinary tract and therefore, stop its proliferation (growth)(3). This can help reduce the incidence of UTIs. However, the amount of PACs in cranberry juice can be limited and will also come with the added sugar and calories. Therefore, taking a supplement with cranberry extract can offer a highly concentrated and high dosage of PAC, without the sugar and calories. The vitamin C content in cranberries can also acidify the urinary tract environment to reduce the growth of pathogenic bacteria whilst boosting our immune system to help us fight off pathogenic bacteria better.  

Combining friendly bacteria and cranberry extract can work synergistically to reduce the colonisation of E.coli in the urinary tract and therefore, be used to help treat and prevent UTIs. 

It is important to visit your GP if you think you have symptoms of a UTI, your symptoms are severe or getting worse, symptoms haven’t started to improve after a few days or if you get UTIs frequently. GPs are able to test a sample of your urine and prescribe antibiotics if you do have an infection.

If you'd like to learn more about the female intimate microbiome, why not book a free 1:1 consultation with our nutrition team? We can recommend diet and lifestyle changes that can make a big difference. To book, simply click here.


  1. NHS. Urinary tract infections (UTI). NHS inform. 2019.
  2. CA C, TM H. Update on acute uncomplicated urinary tract infection in women. Postgrad Med J. 2006;119(1):39–45. 
  3. Asma B, Vicky L, Stephanie D, Yves D, Amy H, Sylvie D. Standardised high dose versus low dose cranberry Proanthocyanidin extracts for the prevention of recurrent urinary tract infection in healthy women [PACCANN]: A double blind randomised controlled trial protocol. BMC Urol. 2018;18(1):1–7. 
  4. Dason S, Dason JT, Kapoor A. Guidelines for the diagnosis and management of recurrent urinary tract infection in women. J Can Urol Assoc. 2011;5(5):316–22. 
  5. A E, A L, D L, JE W, W E, SA F, et al. Recurrent urinary tract infections. J Obstet Gynaecol Canada. 2010;32(11):1082–101.
  6. Al-Badr A, Al-Shaikh G. Recurrent urinary tract infections management in women: A review. Sultan Qaboos Univ Med J. 2013;13(3):359–67. 
  7. Akgül T, Karakan T. The role of probiotics in women with recurrent urinary tract infections. Turkish J Urol. 2018;44(5):377–83. 
  8. Cribby S, Taylor M, Reid G. Vaginal Microbiota and the Use of Probiotics. Interdiscip Perspect Infect Dis. 2008;2008:1–9.