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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 diabetes.

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 have:

  • more blood tests
  • a special x-ray of the kidneys called an intravenous pyelogram (IVP)
  • an ultrasound scan.

The IVP and ultrasound scan can show problems in the urinary tract.

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)
  • diabetes
  • kidney stones
  • kidney transplant
  • advanced age.

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 urinary tract.
  • 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 cotton crotch.
  • 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.

Developed by McKesson Provider Technologies.
Published by McKesson Provider Technologies.
Last modified: 2005-03-21
Last reviewed: 2003-10-19
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.
Copyright 2005 McKesson Corporation and/or one of its subsidiaries. All Rights Reserved.
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