A new study by researchers at Loyola University suggests that the common notion that human urine is sterile is not always true. A post at the science blog Lab Spaces says that tests have shown that certain bacteria commonly inhabit the bladders of some women, and that new approaches to testing for and treating urinary tract infections (UTIs) are in order.

In the April Issue of the Journal of Clinical Microbiology, researchers from the Loyola University Chicago Stritch School of Medicine (SSOM) presented findings that suggest challenge generations of conventional wisdom. SSOM’s dean, Linda Brubaker, MD, MS said, “Doctors have been trained to believe that urine is germ-free. 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.”

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Researchers used DNA-based testing methods to examine urine from women with symptoms of UTIs, but who were coming up negative for common infections. Urine was collected in three ways, by “standard urination,” by catheterization and by the insertion of a thin needle through the abdominal wall while under anesthesia for gynecological surgery.

Tests determined that the adult female bladder can contain multiple forms of bacteria that are not identified by normal urine culture techniques of the kind normally used to detect UTIs. Alan Wolfe, Ph.D., one of the study’s co-authors said that while urine culture’s have been the “gold standard” of UTI detection, they are not as effective as DNA-based testing and therefore of limited utility.

The study also looked at collection methods for urine samples. It found that samples collected by catheterization and needle collection were much less likely to be contaminated than those obtained by the normal method of catching the urine in a cup, which are often contaminated by vaginal bacteria.

The Loyola team now hopes to catalog the bacteria and sort out their relationships to each other as well as to their host, determining which are helpful and which may be harmful. The study is part of a larger international study to inventory the the “core bacterial composition of a healthy human body.”

It is estimated that one in five adult women has contracted a UTI, which is a common reason women visit emergency rooms each year.

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