No, Your Urine Is Not Sterile

Illustration for article titled No, Your Urine Is Not Sterile

There's a widely held belief that urine, except in cases of kidney or urinary tract infections, is sterile. It's a myth that won't go away — but a recent study linking bacteria to the bladders of healthy women should finally put this tired notion to rest.


This finding was recently presented by researchers from Loyola University Chicago at the 114th General Meeting of the American Society for Microbiology in Boston.

"Doctors have been trained to believe that urine is germ-free," noted co-investigator Linda Brubaker in a statement. "These findings challenge this notion, so this research opens the door to exciting new possibilities for patient treatment."

In addition to showing that bacteria live in the bladders of healthy women, the researchers also discovered that bladder bacteria in healthy women differs from the bladder bacteria in women suffering from a condition called overactive bladder (OAB), which causes a sudden need to urinate.

The thinking now is that certain types of bacteria may be beneficial, while others may be contributing to OAB. From the Loyola release:

Approximately 15 percent of women suffer from OAB and yet an estimated 40-50 percent do not respond to conventional treatments. One possible explanation for the lack of response to medication may be the bacteria present in these women.

"If we can determine that certain bacteria cause OAB symptoms, we may be able to better identify those at risk for this condition and more effectively treat them," said Alan Wolfe, PhD, co-investigator and professor of Microbiology and Immunology, SSOM.

This study evaluated urine specimens of 90 women with and without OAB symptoms. Urine samples were collected through a catheter and analyzed using an expanded quantitative urine culture (EQUC) technique. This EQUC technique was able to find bacteria that are not identified by the standard urine culture techniques typically used to diagnose urinary tract syndromes.

"While traditional urine cultures have been the gold standard to identify urine disorders in the past, they do not detect most bacteria and have limited utility as a result," said Paul Schreckenberger, PhD, director, clinical microbiology laboratory, Loyola University Health System. "They are not as comprehensive as the EQUC protocol used in this study."

The researchers will now try to determine which bacteria in the bladder are helpful, which are harmful, and how they all interact with each other. This work is part of a broader project investigating the core bacterial composition of a healthy human body.

[ Loyola Medicine ]

Image: Csaba Deli/Shutterstock



Calling it a "myth" and a "tired notion" in the lede makes it sound like some sort of ridiculous old wives' tale that only the extremely gullible would believe. But then he goes on to say, "Doctors have been trained to believe that urine is germ-free," indicating that this is a concept that is widely accepted in the medical community, and it's just this one study that contradicts that notion. Does anyone know which it is?