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Urine Tests Don't Always Confirm Urinary Infections, Study Finds

Doctors can rely on symptoms to start treatment, experts say

WebMD News from HealthDay

By Serena Gordon

HealthDay Reporter

WEDNESDAY, Nov. 13 (HealthDay News) -- When doctors suspect a patient has a urinary tract infection, they often request a urine sample so they can test for the presence of bacteria. Now, new research suggests this step may be unnecessary.

Nearly one-quarter of women who had signs of a urinary tract infection -- a burning feeling when urinating or feeling an urgent need to pee -- had no evidence of bacteria in their urine or in their bladders, the study found. And although a number of urine culture tests found a variety of different bacteria, only one bug -- Escherichia coli -- was found in both the urine test and the bladder.

These findings suggest that today's lab tests may not be refined enough to detect very small quantities of bacteria in the bladder. It's also possible that the symptoms may not be caused by a bladder infection, but instead may be caused by an infection in the urethra, the tube that allows urine to pass out of the body. Or, inflammation in the urethra might be causing the symptoms, rather than bacteria.

"Our study provides further evidence that midstream urine cultures don't routinely need to be done. Most labs don't quantify low enough unless you specifically ask them to. Most women are treated right away for symptoms anyway, because the urine culture doesn't come back for two days," explained the study's lead author, Dr. Thomas Hooton, a professor of medicine at the University of Miami Miller School of Medicine in Florida.

Hooton added that a short course of antibiotics is likely to be effective, and that it's important to keep studying urinary tract infections. In particular, he said, "we need to know more about exactly what causes symptoms."

Results of the study were published in the Nov. 14 issue of the New England Journal of Medicine.

Urinary tract infections (also called UTIs or acute cystitis) are common bacterial infections, responsible for about 9 million doctor's visits in the United States every year, according to the study.

The bacteria responsible for the infection is generally found through a test of urine collected when someone goes to the bathroom. Urine collected directly from the bladder would yield more accurate results because there are fewer places for the urine to potentially become contaminated. But collecting urine from the bladder requires insertion of a catheter, an uncomfortable, invasive and more expensive procedure.

However, the 226 women included in the current study volunteered to collect a midstream urine sample, and immediately after allowed another sample to be collected directly from their bladder via a catheter.

All of the women were healthy, premenopausal women who had symptoms of a bladder infection.

When the researchers found E. coli in the midstream urine sample, it was also quite likely that they would find it in the bladder urine, too. However, when other types of bacteria were found in the midstream urine sample, they often didn't correlate to bacteria in the bladder.

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