Urine not as sterile as doctors thought

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CHICAGO, April 9 (UPI) -- Doctors have long believed normal urine is sterile, but U.S. researchers found bacteria can be present in the bladders of healthy women.

Dr. Linda Brubaker, dean of the Loyola University Chicago Stritch School of Medicine, and colleagues evaluated urine specimens of women who had symptoms consistent with a urinary tract infection, but were free of known urinary tract infections.

Urine samples were collected from standard urination, via a catheter, or from a thin needle inserted into the abdomen while the women were under anesthesia for gynecologic surgery, Brubaker said.

The urine was analyzed using advanced DNA-based detection methods and these tests determined the adult female bladder could contain certain forms of bacteria not identified by urine culture techniques typically used to diagnose urinary tract infections, Brubaker said.

"Doctors have been trained to believe that urine is germ-free," Brubaker said in a statement. "However, these findings challenge this notion, so this research may have positive implications for how we treat patients with urinary tract conditions in the future."

The study published in the Journal of Clinical Microbiology found urine cultures that have been the gold standard to identify urinary tract infections in the past have limited utility and are not as effective as the DNA-based detection measures used.

The researchers also found the standard method to catch urine in a cup poses problems, because bacteria from the vagina often contaminate these samples.