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Bacteriuria pyuria 4.jpg
Multiple rod-shaped bacteria shown between the larger white blood cells at urinary microscopy from a person with urinary tract infection.
SpecialtyEmergency medicine, Infectious disease
TypesAsymptomatic, symptomatic[1][2]
Diagnostic methodUrinalysis, urine culture[3]
Differential diagnosisContamination[1]
TreatmentBased on symptoms or risk factors[4][3]
FrequencyAsymptomatic: 3% (middle aged women), up to 50% (women in nursing homes)[5]
Symptomatic: up to 10% of women a year[6][7]

Bacteriuria is the presence of bacteria in urine.[1] It is divided into two main types, those with symptoms (urinary tract infection) and those without (asymptomatic bacteriuria).[1][2] Diagnosis is by urinalysis or urine culture.[3] Escherichia coli is the most common bacterium found.[1] Most people without symptoms should not be tested for the condition.[3] Differential diagnosis include contamination.[1] Using special techniques certain non-disease causing bacteria have also been found in the urine of healthy people.[8] These are part of the resident microbiota.[8]

If symptoms are present treatment is generally with antibiotics.[3] Bacteriuria without symptoms generally does not require treatment.[4] Exceptions include during pregnancy, those who have had a recent kidney transplant, young children with significant vesicoureteral reflux, and in those undergoing surgery of the urinary tract.[4][3]

Bacteriuria without symptoms is present in about 3% of otherwise healthy middle aged women.[5] Among those in nursing homes rates are as high as 50% among women and 40% in men.[5] In those with a long term indwelling urinary catheter rates are 100%.[5] Up to 10% of women have a urinary tract infection in a given year and half of women having at least one infection at some point in their lives.[6][7]

Signs and symptoms[edit]

Asymptomatic bacteriuria[edit]

Asymptomatic bacteriuria is bacteriuria without accompanying symptoms of a urinary tract infection. It is more common in women, in the elderly, in residents of long-term care facilities, and in people with diabetes, bladder catheters and spinal cord injuries. People with a long-term Foley catheter uniformly show bacteriuria. Chronic asymptomatic bacteriuria without urinary tract infection symptoms occurs in as many as 50% of the population in long-term care.[9]

In pregnant women bacteriuria is associated with low birth weight, preterm delivery, and infection of the newborn.[10][11] Bacteriuria in pregnancy also increase the risk of preeclampsia.[11]

Symptomatic bacteriuria[edit]

Symptomatic bacteriuria is bacteriuria with the accompanying symptoms of a urinary tract infection (such as frequent urination, painful urination, fever, back pain). Symptomatic bacteriuria can be indicative of a urinary tract infection like pyelonephritis or cystitis. The most common type of bacteriuria associated with urinary tract infections is Escherichia coli which is a gram-negative rod-shaped bacteria.


Testing for bacteriuria is often performed in those with symptoms of a urinary tract infection. Testing is often done in other scenarios as in failure to thrive of a newborn or confusion in the elderly. Screening for bacteriuria is recommended in pregnancy as there is evidence that asymptomatic bacteriuria can lead to low birth weight and preterm delivery.

  • Bacteriuria can be detected by urine dipstick test. The urinary nitrite test will be able to detect any nitrate-reducing bacteria in the urine. The leukocyte esterase test detects the presence of leukocytes (white blood cells) in the urine which can be associated with a urinary tract infection.The urine dipstick test is readily available and provides fast results.
  • Microscopy can also be used to detect bacteriuria. It is more specific, especially when used with gram staining, but requires more time and equipment.
  • The gold standard for detecting bacteriuria is a bacterial culture which identifies the actual organism. This test is more specific but can take several days to obtain a result. As a result, clinicians will often treat a bacteriuria based on the results of the urine dipstick test while waiting for the culture results. The culture will often provide antibiotic sensitivity.

Bacteriuria can be confirmed if a single bacterial species is isolated in a concentration greater than 100,000 colony forming units per millilitre of urine in clean-catch midstream urine specimens (one for men, two consecutive specimens with the same bacterium for women).[12] For urine collected via bladder catheterization in men and women, a single urine specimen with greater than 100,000 colony forming units of a single species per millilitre is considered diagnostic.[12] The threshold is also 100 colony forming units of a single species per millilitre for women displaying UTI symptoms.[13]


One time screening for bacteriuria is tentatively recommended during early pregnancy.[14]


The decision to treat bacteriuria depends on the presence of accompany symptoms and comorbidities.

Asymptomatic bacteriuria[edit]

Asymptomatic bacteriuria generally does not require treatment.[4] Exceptions include during pregnancy and in those undergoing surgery of the urinary tract.[4][15] Children with vesicoureteral reflux or others with structural abnormalities of the urinary tract.[16][unreliable medical source?]

There is no indication to treat asymptomatic bacteriuria in diabetics, renal transplant recipients, and in those with spinal cord injuries.[17]

The overuse of antibiotic therapy to treat asymptomatic bacteriuria has many adverse effect[18] as it increases the risk of diarrhea, antimicrobial resistance, and infection due to Clostridium difficile. Other effects include increased financial burdens and overreporting of mandated catheter-associated urinary tract infection.

Symptomatic bacteriuria[edit]

Symptomatic bacteriuria is typically treated as a urinary tract infection with antibiotics. Common choices include nitrofurantoin, and trimethoprim/sulfamethoxazole.


Rates of asymptomatic bacteriuria[5]
Group Prevalence (in %)
Healthy premenopausal women 1.0 to 5.0
Pregnant women 1.9 to 9.5
Postmenopausal women (50 to 70 years of age) 2.8 to 8.6
People with diabetes mellitus Women 9.0 to 27.0
Men 0.7 to 1.0
Older community-dwelling people Women (older than
70 years)
> 15.0
Men 3.6 to 19.0
Older long-term care residents Women 25.0 to 50.0
Men 15.0 to 40.0
People with spinal cord injury Intermittent catheter 23.0 to 89.0
Sphincterotomy and
condom catheter
People undergoing hemodialysis 28.0
People with an indwelling
urinary catheter
Short-term 9.0 to 23.0
Long-term 100


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External links[edit]

External resources