Urinary tract infections (UTIs) can affect both men and women at any stage of life. The Urology Care Foundation estimates 40 percent of women and 12 percent of men will experience UTI symptoms in their lifetime. UTIs account for more than eight million doctor visits annually. A UTI is typically recognized at home, before going to the doctor, because the signs are usually sudden and uncomfortable. The most common early symptoms begin as pain or burning while urinating, cloudy or off-smelling urine, pain in the lower abdomen, and/or the urge to urinate often, all of which can worsen as the infection progresses or is ignored.

What causes a UTI?

A UTI usually occurs when harmful bacteria translocate from the skin or rectum to a person’s urethra. Although the bacteria can affect several parts of the urinary tract, the most common infection occurs from the lower urinary tract to the bladder. Women tend to experience UTIs more frequently than men (estimated to be eight-times more likely) because of anatomical differences – a woman’s urethra is shorter and closer to the rectum than a man’s. 

There are many lifestyle factors that put a person at risk for a UTI, including being sexually active, having structural changes in the urinary tract (for example, in men, an enlarged prostate), and having poor hygiene. Quite often, changes in hormone levels – naturally occurring with life stages such as puberty, pregnancy, and menopause, or occurring for reasons like stress, inactivity, or a health condition – induce bacterial shifts in the skin, gut, and vaginal microbiomes, also influencing the risk for a UTI. Individuals who experienced one UTI are at a higher risk for having another. Recent research indicates that 25 percent of women will develop a second UTI within six months of having their first.1 

How is the microbiome involved?

Strong evidence suggests that UTIs are significantly related to the health of the gut microbiome. Escherichia coli (E. coli) has long been the bacteria of interest. Although this fast-growing, aerobic microorganism regularly lives in the human gut, E. coli tends to become a problem when it translocates to the urinary tract or when it becomes overabundant. There can also be more harmful bacterial strains that are present. Although these reasons hold true in approximately 80 percent of cases,2 research also shows that other differences and imbalances in the gut microbiome play a role. 

With so many yearly and recurring cases, it is easy to say this is not a simple or straightforward health concern; rather, it is an incredibly complex issue and there are many systems involved. Here, we explore some of the newer research linking the gut microbiome to UTIs. 

A recent 1-year study of females showed similar levels of E. coli in the guts of women who had frequent infections compared to those who didn’t have reoccurring infections. It also reported fewer gut microbial species, elevated Bacteroidetes, lower relative abundances of Firmicutes, fewer bacteria that produce short-chain fatty acids (butyrate), and higher general gut inflammation.1 Other studies show associations between an increase in the gut microbiome composition of Enterococcus and Staphylococcus with a higher prevalence of UTIs.3,4 

The gut doesn’t act alone. It constantly cross-communicates with the body’s other microbiomes that play a role, too. Although probably less known, there is such a thing as a urinary microbiome. Here, some of the opportunistic bacteria that are likely associated with UTIs include Corynebacterium glucuronolyticum, Streptococcus gallolyticus, and Aerococcus sanguinicola.5,6 

In women, the vaginal microbiome is a unique environment to consider. Bacterial vaginosis caused by an overgrowth of certain anaerobic species increases the risk of a UTI. Research shows that even slight exposure to Gardnerella vaginalis can activate E. coli that might otherwise remain dormant in the bladder.7 Some bacteria have even been shown to promote the growth of other coinfecting organisms. For example, Enterococcus faecalis can stimulate the growth and survival of E. coli.8 On the other hand, one study found an intervaginal suppository of Lactobacillus crispatus actually reduced recurrent UTIs in premenopausal women.9

What are the options moving forward?

Although oral antibiotics can normally and quickly alleviate symptoms, for about 25 percent of women, relief might be only temporary because the root problem is not addressed.1 Some women require repeated rounds or continual use of antibiotics for reoccurring UTIs during their lifetime. In fact, the most commonly prescribed antibiotics for UTIs might not permanently clear the UTI-causing bacterial strains from the gut.1 And multiple rounds of antibiotic therapy can put a woman at risk for more gut and vaginal dysbiosis, compounding the imbalances that already exist.

Individuals who are at risk for having poor urinary tract health should evaluate their gut microbiome to learn what bacteria are present, to know how to increase or decrease their abundance, and to know if there is a need for diet, lifestyle, and supplement changes to optimize the gut microbiome’s health. 

Consider Thorne’s Women’s Daily Probiotic, an exclusive blend of eight research-backed, beneficial bacterial strains that support healthy vaginal, urinary, and gut microbiomes; regulate vaginal pH; and rebalance bacteria levels.* 

References

  1. Worby CJ, Schreiber HL 4th, Straub TJ, et al. Longitudinal multi-omics analyses link gut microbiome dysbiosis with recurrent urinary tract infections in women. Nat Microbiol 2022;7(5):630-639.
  2. Perez-Carrasco V, Soriano-Lerma A, Soriano M, et al. Urinary microbiome: yin and yang of the urinary tract. Front Cell Infect Microbiol 2021;11:617002.
  3. Magruder M, Sholi AN, Gong C, et al. Gut uropathogen abundance is a risk factor for development of bacteriuria and urinary tract infection. Nat Commun 2019;10(1):5521.
  4. Paalanne N, Husso A, Salo J, et al. Intestinal microbiome as a risk factor for urinary tract infections in children. Eur J Clin Microbiol Infect Dis 2018;37(10):1881-1891.
  5. Ruiz-Pino M, Foronda-García-Hidalgo C, Alarcón-Blanco P, Gutiérrez-Fernández J. Male genitourinary infections by Corynebacterium glucuronolyticum. A review and clinical experience. Rev Esp Quimioter 2019;32(5):479-484.
  6. Pereira-Pérez E, Aparicio-Gómez JA, Gómez-Camarasa C, Gutiérrez-Fernández J. A study of urinary tract infections by Streptococcus gallolyticus ssp. pasteurianus. Rev Esp Quimioter 2019;32(2):189-191.
  7. Garretto A, Thomas-White K, Wolfe AJ, Putonti C. Detecting viral genomes in the female urinary microbiome. J Gen Virol 2018;99(8):1141-1146.
  8. Kawai K, Kamochi R, Oiki S, et al. Probiotics in human gut microbiota can degrade host glycosaminoglycans. Sci Rep 2018;8(1):10674.
  9. Stapleton AE, Au-Yeung M, Hooton TM, et al. Randomized, placebo-controlled phase 2 trial of a Lactobacillus crispatus probiotic given intravaginally for prevention of recurrent urinary tract infection. Clin Infect Dis 2011;52(10):1212-1217.