Bladder Urine Is Not Sterile

Alan J. Wolfe PhD, Professor Department of Microbiology and Immunology Stritch School of Medicine, Loyola University Chicago Maywood, Interview with:
Alan J. Wolfe PhD, Professor
Department of Microbiology and Immunology
Stritch School of Medicine, Loyola University Chicago
Maywood, IL

Medical Research: What is the background for this study?

Dr. Wolfe: Several years ago, Dr. Brubaker and I began a conversation. As a urogynecologist, she was concerned about the general lack of improvement in diagnosis and treatment in her urogynecological practice and thus in clinical outcome. As a microbiologist, I was extremely skeptical of the dogma that urine in the bladder was sterile in the absence of a clinical infection. This skepticism was based upon my former work in bacterial motility and biofilm formation and on the knowledge that most bacteria are not cultured by the standard clinical microbiology urine culture method. With the goal of ultimately improving urogynecological practice, and with the help of our colleagues in the Loyola Urinary Education and Research Collaborative (LUEREC), we decided to test the sterile bladder hypothesis by seeking evidence of bacteria in urine taken directly from the bladder to avoid vulva-vaginal contamination. To detect bacterial DNA, we used high-throughput DNA sequencing technology. To detect live bacteria, we developed an Expanded Quantitative Urine Culture (EQUC) protocol. We applied these complementary approaches to women with and without urgency urinary incontinence (UUI) whose standard clinical urine culture was negative.

Medical Research: What are the main findings?

Dr. Wolfe: First and foremost, the bladder is not sterile. We can detect bacteria and/or bacterial DNA in most women whether they have urgency urinary incontinence (UUI) or not. Thus, the female bladder contains a resident bacterial community, which we call the female urinary microbiome (FUM). We found that bacterial members of the FUM are distinct from the bacteria that typically cause urinary tract infections (UTI). Thus, the bacteria that make up the FUM are not the bacteria that cause typical UTIs. Indeed, detection of the female urinary microbiome was associated with reduced risk of UTIs that often occur after instrumentation or surgery. We therefore hypothesize that the FUM or some members of the FUM could protect against UTI. We also saw that the FUM in women with UUI differs from the FUM in women without UUI and that certain bacterial species were considerably more common in women with urgency urinary incontinence than in women without urgency urinary incontinence . We hypothesize that some of these bacteria could be causative or contributory to UUI or they could be a consequence of urgency urinary incontinence.

Medical Research: What should clinicians and patients take away from your report?

Dr. Wolfe: This is just a beginning. Much more research must be done to be able to bring substantial benefits to patients. However, our work has already altered clinical microbiology laboratory protocol and urogynecological practice at the Loyola University Medical Center and we believe that these changes have made a difference.

Medical Research: What recommendations do you have for future research as a result of this study?

Dr. Wolfe: Most importantly, researchers and clinicians must reassess dogma, etiological theories, diagnostic methods and therapies that are based on the incorrect assumption that the bladder is sterile. For our part, LUEREC has broadened its focus to other disorders of the lower urinary tract, such as painful bladder syndrome and recurrent UTI. We have begun to explore the urinary microbiomes of men and pregnant women. We have begun to investigate the hundreds of different bacteria that we cultured using EQUC, trying to learn as much as we can, especially their interactions with pathogenic bacteria that cause UTI and with the epithelial cells that line the lumen of the bladder


“Sterile Urine” and the Presence of Bacteria
Alan J. Wolfe , Linda Brubaker

European Urology  Available online 12 March 2015 Interview with: Alan J. Wolfe PhD, Professor (2015). Bladder Urine Is Not Sterile