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Asymptomatic bacteriuria

Most of the time, your urine is sterile. This means there is no bacteria growing. On the other hand, if you have symptoms of a bladder or kidney infection, bacteria will be present and growing in your urine.

Sometimes, your health care provider may check your urine for bacteria even when you do not have any symptoms. If enough bacteria are found in your urine, you have asymptomatic bacteriuria.

Causes

Asymptomatic bacteriuria occurs in a small number of healthy people. It affects women more often than men. The reasons for the lack of symptoms are not well understood.

You are more likely to have this problem if you:

  • Have a urinary catheter in place
  • Are female
  • Are pregnant
  • Are sexually active (in females)
  • Have long-term diabetes and are female
  • Are older adults
  • Have recently had a surgical procedure in your urinary tract

Symptoms

There are no symptoms of this problem.

If you have these symptoms, you may have a urinary tract infection but you DO NOT have asymptomatic bacteriuria.

Exams and Tests

To diagnose asymptomatic bacteriuria, a urine sample must be sent for a urine culture. Most people with no urinary tract symptoms do not need this test.

You may need a urine culture done as a screening test even without symptoms if:

  • You are pregnant
  • You have a surgery or procedure planned that involves bladder, prostate, or other parts of the urinary tract
To make the diagnosis of asymptomatic bacteriuria, the culture must show a large growth of bacteria.
  • In men, only one culture needs to show growth of bacteria
  • In women, two different cultures must show growth of bacteria

Treatment

Most people who have bacteria growing in their urine, but no symptoms, do not need treatment. This is because the bacteria are not causing any harm. In fact, treating most people with this problem may make it harder to treat infections in the future.

However, for some people getting a urinary tract infection is more likely or may cause more severe problems. As a result, treatment with antibiotics may be needed if:

  • You are pregnant.
  • You had a kidney transplant recently.
  • You are scheduled for surgery involving the prostate gland, the bladder and those with infected kidney stones.
  • Young children with reflux (backward movement of urine from the bladder into ureters or kidneys).

Without symptoms being present, even those who are older adults, have diabetes, or have a catheter in place, do not need treatment.

Possible Complications

If it is not treated, you may have a kidney infection if you are at high risk.

When to Contact a Medical Professional

Call your provider if you have:

  • Difficulty emptying your bladder
  • Fever
  • Flank or back pain
  • Pain with urination

You will need to be checked for a bladder or kidney infection.

Alternative Names

Screening - asymptomatic bacteria

References

Dull RB, Friedman SK, Risoldi ZM, Rice EC, Starlin RC, Destache CJ. Antimicrobial treatment of asymptomatic bacteriuria in noncatheterized adults: a systematic review. Pharmacotherapy. 2014;34(9):941-960. PMID: 24807583 www.ncbi.nlm.nih.gov/pubmed/24807583.

Schaeffer AJ, Matulewicz RS, Klumpp DJ. Infections of the urinary tract. In: Wein AJ, Kavoussi LR, Partin AW, Peters CA, eds. Campbell-Walsh Urology. 11th ed. Philadelphia, PA: Elsevier; 2016:chap 12.

Zalmanovici Trestioreanu A, Lador A, Sauerbrun-Cutler MT, Leibovici L. Antibiotics for asymptomatic bacteriuria. Cochrane Database Syst Rev. 2015;4:CD009534. PMID: 25851268 www.ncbi.nlm.nih.gov/pubmed/25851268.

Review Date 7/22/2016

Updated by: Linda J. Vorvick, MD, Clinical Associate Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.