Harvard Health A-Z

Asymptomatic Bacteriuria

What Is It?

When a significant number of bacteria show up in the urine, it usually means there is an infection somewhere in the urinary tract (kidneys, ureters, bladder, urethra). A urinary tract infection usually causes several symptoms, including pain or burning during urination.

In asymptomatic bacteriuria, large numbers of bacteria (at least 100,000 bacteria per milliliter) are present in the urine, but the patient has no symptoms of a urinary tract infection (asymptomatic means without symptoms). It is unclear why the bacteria don?t cause symptoms. It may be that asymptomatic bacteruria is caused by weaker (less ?virulent?) organisms. The condition does not always need to be treated.

Asymptomatic bacteriuria is most common in women, and in patients with diabetes, the elderly, and in those with indwelling urinary catheters.

Symptoms

Asymptomatic bacteriuria does not cause any symptoms.

Diagnosis

Your doctor will determine that you have asymptomatic bacteriuria based on laboratory testing of your urine that shows at least 100,000 bacteria per milliliter of urine. To confirm that you do not have any symptoms of a urinary tract infection, your doctor will ask you detailed questions about your urine, including questions about its color, odor, and whether you have noticed any blood in your urine. He or she also will ask about the number of times you urinate during the day and at night and whether you have had any episodes of bedwetting, pain during urination, an urgent need to urinate or fever.

Sometimes, high numbers of bacteria show up in urine tests if the urine was collected or stored improperly. Therefore, your doctor will ask you to give additional urine samples to confirm the presence of the same type of bacteria. These samples will be sent for testing to identify the specific type of bacteria and to identify specific antibiotics that can be used to eliminate the bacteria.

Expected Duration

In some people, asymptomatic bacteriuria eventually progresses to a full-blown urinary tract infection, with the usual symptoms. In other people, asymptomatic bacteriuria can continue for years without causing obvious illness or discomfort.

Prevention

You can help to prevent asymptomatic bacteriuria by drinking several glasses of water each day. This will discourage the growth of bacteria by flushing out your urinary tract. Drinking cranberry juice every day might also deter the growth of bacteria by making your urine more acidic, but this has not been definitively shown through adequate medical studes.

To prevent the spread of intestinal bacteria from the rectum to the urinary tract, women should always wipe toilet tissue from front to back after having a bowel movement.

Treatment

Antibiotic treatment for asymptomatic bacteriuria is recommended for the following groups of patients:

• Children

• Patients with obstruction or abnormal structure of the urinary tract

• Pregnant women

• Men about to undergo urologic or prostate surgery

• People who have had a kidney transplant

Most patients with asymptomatic bacteriuria are elderly women who do not require treatment. Although treatment often will clear the bacteria from the urine, the condition often returns. Your doctor will usually wait until the results of two urine cultures have confirmed the presence of bacteria before beginning treatment. At that point, your doctor will have been able to identify the type of bacteria and determine the most effective antibiotic to treat it. For patients with indwelling urinary catheters, the bacteriuria after treatment, therefore, antibiotic therapy might be withheld if patient has no symptoms. However, these patients must be monitored closely for the development of symptoms.

When To Call A Professional

If you have asymptomatic bacteriuria, call your doctor immediately if you begin urinating more often than normal; develop an intense need to urinate; have pain during urination; or if your urine becomes discolored, cloudy or foul smelling.

Prognosis

The outlook is good. For most patients, asymptomatic bacteriuria does not cause any problems and treatment is not necessary.

Additional Info

National Kidney Foundation30 East 33rd St.New York, NY 10016Phone: (212) 889-2210Toll-Free: (800) 622-9010Fax: (212) 689-9261E-Mail: info@kidney.orghttp://www.kidney.org/

American Foundation for Urologic Disease1000 Corporate Blvd., Suite 410Linthicum, MD 21090Phone: (410) 689-3990Toll-Free: (800) 828-7866Fax: (410) 689-3998http://www.afud.org/

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