Asymptomatic bacteriuria

Asymptomatic bacteriuria is a bacterial Urinary tract infection that occurs without any of the usual symptoms.

Causes, incidence, and risk factors

Asymptomatic bacteriuria occurs in up to 6% of healthy individuals. It affects 18% of diabetics (mostly women) and 20% of elderly individuals (more often women than men). The reasons for the lack of symptoms are not well understood.

Most patients with asymptomatic bacteriuria do not need treatment because the bacteria isn’t causing any harm. However, certain groups are at a higher risk for kidney infections if they develop asymptomatic bacteriuria. Those at risk include:

  • People with Diabetes  
  • Elderly people  
  • Pregnant women - if asymptomatic bacteriuria is left untreated, up to 40% will develop a kidney infection (pyelonephritis).  
  • Renal (kidney) transplant patients  
  • Young children with vesicoureteral reflux  
  • Patients with infected Kidney stones

By definition, asymptomatic bacteriuria causes no symptoms of a Urinary tract infection

Signs and tests
Asymptomatic bacteriuria is detected by the discovery of significant bacterial growth in a urine culture taken from a urine sample.


Not all patients with asymptomatic bacteriuria respond to treatment. Pregnant women, renal transplant recipients, children with vesicoureteral reflux and people with infected Kidney stones appear to be more likely to benefit from treatment with antibiotics.

In addition, if asymptomatic bacteriuria is found prior to a urological procedure, it should be treated to prevent complications of the procedure. The course of therapy in these cases depends on underlying risk factors.

Expectations (prognosis)

Most individuals with asymptomatic bacteriuria who do not have risk factors for complications do extremely well and do not have any increased rates of symptomatic infections or decrease in kidney function.

The prognosis for treatment in the high-risk group category is favorable if infection is detected early, but much depends on the underlying conditions or illnesses of the individual.

Individuals in high-risk groups have a significant risk of progressing to a true kidney infection if the bacteriuria is not treated. In certain cases, such as renal transplant recipients, kidney infection may lead to loss of kidney function.

Calling your health care provider

If you have been told you have asymptomatic bacteriuria and you are in a high-risk group for complications, notify your health care provider. Also, if you begin to develop fever, have difficulty emptying your bladder, feel pain with urination, or have flank or back pain - notify your health care provider. You will need to be evaluated for a bladder or kidney infection.

Johns Hopkins patient information

Last revised: December 4, 2012
by Janet G. Derge, M.D.

Medical Encyclopedia

  A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | 0-9

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.