(See also Overview of Urinary Tract Infections [UTIs] Overview of Urinary Tract Infections (UTIs) In healthy people, urine in the bladder is sterile—no bacteria or other infectious organisms are present. The tube that carries urine from the bladder out of the body (urethra) contains no bacteria... read more .)
Asymptomatic bacteriuria is common in certain groups of people, such as those who have bladder catheters inserted for an extended period. Asymptomatic bacteriuria is not normally treated because eradicating the bacteria can be difficult and complications are usually rare. Also, giving antibiotics can alter the balance of bacteria in the body, sometimes allowing bacteria that are more difficult to eliminate to flourish.
An exception is if the person has a condition that makes a urinary tract infection (UTI) particularly risky. Such conditions may include
Pregnancy
Having a condition that suppresses the immune system Overview of Immunodeficiency Disorders Immunodeficiency disorders involve malfunction of the immune system, resulting in infections that develop and recur more frequently, are more severe, and last longer than usual. Immunodeficiency... read more (for example, AIDS, certain cancers, or having a low white blood cell count)
Young children with severe backflow (reflux) of urine from the bladder into the ureters Urinary Reflux Urinary reflux is when urine flows backward from the bladder into the ureter and sometimes the kidney, usually because of a birth defect of the urinary tract. Each kidney continuously filters... read more
Before certain invasive procedures that can cause bleeding in the urinary tract (for example, transurethral resection of the prostate)
For example, a bladder infection (cystitis Bladder Infection Cystitis is infection of the bladder. Usually, bacteria are the cause of cystitis. A frequent need to urinate and pain or burning while urinating are the most common symptoms. Doctors can often... read more 
) can seriously complicate pregnancy by ascending to the kidneys and causing a kidney infection (pyelonephritis Kidney Infection Pyelonephritis is a bacterial infection of one or both kidneys. Infection can spread up the urinary tract to the kidneys, or uncommonly the kidneys may become infected through bacteria in the... read more ), leading to early labor. Also, a UTI can damage a transplanted kidney. A UTI can cause potentially fatal bloodstream infection Sepsis and Septic Shock Sepsis is a serious bodywide response to bacteremia or another infection plus malfunction or failure of an essential system in the body. Septic shock is life-threatening low blood pressure ... read more in people whose immune system is suppressed by a drug or disorder. Sometimes, the immune system becomes suppressed after cancer chemotherapy. Asymptomatic bacteriuria is also sometimes treated in people who have certain kinds of kidney stones Stones in the Urinary Tract Stones (calculi) are hard masses that form in the urinary tract and may cause pain, bleeding, or an infection or block of the flow of urine. Tiny stones may cause no symptoms, but larger stones... read more 
that cannot be eliminated (and thus cause repeated UTIs) and in people scheduled to have a urinary tract surgical procedure done.
Because asymptomatic bacteriuria is not usually treated, doctors do not usually do tests to identify it unless the person has a condition that warrants such treatment. Bacteriuria can be confirmed by a urine culture Urinalysis and Urine Culture Urinalysis, the testing of urine, may be necessary in the evaluation of kidney and urinary tract disorders and can also help evaluate bodywide disorders such as diabetes or liver problems. A... read more 
, in which bacteria from a urine sample are grown in a laboratory to identify the numbers and type of bacteria. Newer molecular urine testing may sometimes reveal unusual pathogens for recurrent UTI and those that are resistant to treatment. When treatment is warranted, antibiotic therapy is given.
