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Bacteria in Urine, No Symptoms (Asymptomatic Bacteriuria)
What is asymptomatic bacteriuria?
Asymptomatic bacteriuria is a condition in which bacteria
are in your urine, but you have no symptoms of infection.
How does it occur?
Urine is normally sterile, which means that it contains no
bacteria. A small number of bacteria may be found in the
urine of many healthy people. This is usually considered to
be harmless. However, a certain level of bacteria can mean
that the bladder, urethra, or kidneys are infected.
Anything that blocks the flow of urine or prevents the
bladder from emptying completely can cause bacteria to grow
in the urine. For example, a stone or tumor might block the
flow of urine. Prostate enlargement in men might also cause
such a block.
This problem occurs more often in women than men because a
woman's urethra is shorter. (The urethra is the tube that
empties the bladder.) The short urethra makes it easier for
bacteria from the anus or genital area to reach the bladder.
This can happen during such activities as wiping or sexual
intercourse. Most infections of the urinary tract are
caused this way. Bacteria can also enter the urine through
the bloodstream, but this is rare.
If you are healthy, asymptomatic bacteriuria is usually not
a problem and usually does not require treatment. However,
in some cases it is more likely to lead to a kidney
infection; for example, if you are pregnant or have
What are the symptoms?
Asymptomatic bacteriuria has no obvious symptoms.
How is it diagnosed?
Your health care provider may examine you. Your provider
may ask you to provide 2 urine samples about a week apart.
The urine samples will be tested for bacteria. You may also
have some blood tests.
If you have bacteria in your urine more than once, you may
more blood tests
a special x-ray of the kidneys called an intravenous
an ultrasound scan.
The IVP and ultrasound scan can show problems in the urinary
How is it treated?
Your health care provider may or may not prescribe an
antibiotic. If you are healthy and do not have any
underlying problems, you will probably not be prescribed an
antibiotic. If, however, you have a medical condition that
puts you at a higher risk of developing a kidney infection
from asymptomatic bacteriuria, you will be prescribed an
antibiotic. These high-risk conditions are:
pregnancy (asymptomatic bacteriuria may also cause
you to go into labor too early)
You may need to return to your provider's office after you
have taken all of the antibiotic to have your urine tested
again. Your provider may recommend testing your urine
regularly to see if the problem happens again.
In some cases, regular urine testing rather than antibiotic
treatment may be the best course. Your provider will
determine what treatment is best for you.
How long will the effects last?
Asymptomatic bacteriuria usually clears up after treatment
with antibiotics. However, it can come back.
If this problem is not treated, it could become a full-blown
urinary tract infection. If the infection is not then
treated with antibiotics, the kidneys could be damaged.
How can I take care of myself?
If you were prescribed an antibiotic, take all of it as
prescribed, even if you have no symptoms. Do not take
medicine left over from previous infections.
Drink plenty of water each day to cleanse the bladder and
Follow your health care provider's recommendation for
follow-up urine testing to check for recurrence.
What can I do to help prevent asymptomatic bacteriuria?
Women can take the following steps to help prevent a bladder
infection from recurring:
Drink plenty of fluids.
Urinate regularly during the day. Empty your bladder
completely each time.
Keep the vaginal area clean. Wipe from front to back
after a bowel movement.
Urinate before and after intercourse.
Wear cotton underwear, which allows better air
circulation than nylon. Wear pantyhose that have a
Avoid tight clothes in the genital area, such as
control-top pantyhose and tight jeans. Do not wear a wet
bathing suit for long periods of time.
If you have a history of recurrent urinary tract problems,
your health care provider may prescribe small doses of
antibiotics to be taken on a regular basis.
This content is reviewed periodically and is subject to
change as new health information becomes available. The
information is intended to inform and educate and is not a
replacement for medical evaluation, advice, diagnosis or
treatment by a healthcare professional.