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 urinate 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
Short course of antibiotics
"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
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 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.
E. coli the culprit
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 researchers also found
that when other bacteria were in the midstream urine sample, E. coli was
often present in the bladder urine samples.
"E. coli is
probably causing most infections," said Hooton.
Treatment without urine sample
"Our findings are
further confirmation that collection of urine has limited usefulness. You don't
get the results back for two days, and just practically speaking, it's an added
cost because we know E. coli causes most UTIs," noted Hooton.
If your physician decides
to treat you without asking for a urine sample to culture, that's reasonable,
said the author of an accompanying journal editorial, Dr Michael Donnenberg, a
professor of medicine, microbiology and immunology at the University of Maryland
School of Medicine in Baltimore.
But Donnenberg noted that
this study raises a number of questions, too: "Do bacteria in the urethra
cause symptoms? And, if they do, does treating them make the symptoms go away
The test relied on today needs
to be refined if it continues to be used in clinical practice, he suggested.
Millions of these tests are still performed annually, he wrote in the
Both experts said more
research on when antibiotics are helpful and when they're not might help reduce
potentially unnecessary antibiotic use. Reducing unnecessary antibiotic use is
important because of concerns about growing antibiotic resistance.
Learn more about urinary
tract infections from the US
National Library of Medicine.
(Picture: Urine test from Shutterstock)